So, as these tedious life restrictions ease, life slowly returns to normal…
I had registered for the annual remembrance ride to the National Memorial Arboretum (NMA) - aka the Ride To The Wall back in April and, unlike last year when it was cancelled, this year it was go, go, go!

I know my K100LTs like to sulk if they’re not being ridden as often as they would like and they certainly haven’t been ridden much at all of late, so definitely expected to sulk. With this in mind, a couple of weeks before, I gave Gretel the once over, pulled the fuel tank, checked all the electrics, topped up the radiator, disconnected the choke switch as it wasn’t playing nicely (I believe that the switch, which is the same as the front brake switch, only serves to operate the yellow choke light in the instrument cluster but has no other important purpose), got the add on LED rear fog lights working again, and rebuilt her. Fired up beautifully, everything (apart from the choke light) working as it should. A quick test ride down to the local supermarket showed that she was running sweetly and all was good. I filled the tank with E10 - our beloved politicians have bullied the fuel companies and tried to persuade us that E10 is better for the environment and have started phasing out E5 etc along with the small writing warning that it is our responsibility to check our older vehicles as they might not be compatible. Of course it is horseshit…you get 10% ethanol in your fuel, from renewable resources, but you get less mpg/kpl out of the fuel because there is less oomph in the fuel. Net result, you have to refill more often - typically losing 20 miles on a full tank i.e. a 10% reduction in range - so ultimately you use more fuel and that seems kind of ironic as the whole point was to reduce our use of fossil fuels. Anyway, I digress, albeit slightly relevant to the story to come as this was my first full tank of E10 and I was concerned that it could give me issues.

So Gretel was ready, flag poles attached to the panniers to fly my colours at the RTTW (as a flag bearer, you get to ride towards the front of the procession to the NMA. I was excited! I was to travel up on the Friday afternoon, hotel overnight and do the RTTW on Sat 03 Oct and then ride back down on the Sunday. The forecast wasn’t great but at least the Friday was dry and sunny for the ride up, so I had a fighting chance of starting the RTTW with dry gloves etc.

It’s only about a 2 hour ride from home (near Bristol) to Tamworth (hotel near Drayton Manor and my RTTW start point) and hotel check in wasn’t until 1500, so no point setting out too early. Nevertheless, by 1200, I couldn’t wait any longer - the sun was shining, the sky was blue and I was raring to be on the road. I loaded up Gretel, erected the 6 foot flag poles (flags remained off) and I was off. My route was predominantly motorway - M32, M4, M5 and M42 and invariably these routes get pretty congested on a Friday as the entire workforce in the country commute home for the weekend. It didn’t matter, I wasn’t in a rush however, I did note my first mistake - erecting the flag poles. This meant that I couldn’t safely filter/split through traffic jams as I was likely to whack truck wing mirrors with the poles. Of course, Sod’s law being what it is, about 28 miles from home there was a wreck at the side of the M5, police all over the place and all the traffic slowing down to a crawl to rubberneck as they passed the scene. Immediately, the free flowing motorway became 3 lanes of very slow moving and/or stationary traffic and I didn’t dare split lanes. I crawled along patiently, thankful for the fan override switch that enabled me to keep Gretel cool. Eventually, having passed the scene, the traffic started to accelerate again. 

I twisted the throttle, Gretel responded turning the liquid ancient marine organisms into power and noise, with the side serving of vegetables probably just contributing to the noise. I started to pull away from the traffic, I was feeling good, the open road ahead beckoned invitingly and then the engine spluttered and missed a beat. WTF? I was losing power, it was as if I was low on fuel and the the fuel pump was struggling to gain suction. I dropped into 4th gear and moved from the third lane into the middle lane as a precaution. I checked the fuel gauge - I had only ridden 30 miles from home (plus 4 from the supermarket forecourt to home), I still had over ¾ of a tank. I rocked the bike and felt the heavy slosh of fuel…the gauge was telling the truth. The engine spluttered more - my mind raced back to the Northern Tablelands Ride in 2018 when Stan had issues with his fuel hoses/filter…was that my issue? Had that crappy E10 fuel dislodged years of gunk from my fuel system and blocked the fuel filter? My speed was decreasing quickly - I indicated and pulled into the near side lane, there was no response to my desperate twisting of the throttle and then, inevitably the engine died completely and I coasted off onto the motorway hard shoulder. 

I put Gretel on her centre stand, having parked as far to the left of the shoulder as I could. It’s not uncommon for broken down vehicles to get taken out by inattentive motorists who drift onto the hard shoulder. My mind was racing…what was the problem? First things first..get comfortable. Helmet off. Jacket off and hung over the top box in a hopeful effort that the yellow and black would make the bike more noticeable to the vehicles streaming past. I carry a good selection of spares with me, so was confident that I’d be sorted and on my way pronto. 



My mind was going into overdrive - was it the Hall effect sensors? I’ve read that those could go duff and would start working again when the engine cooled down. Had the engine been running too hot in the traffic jam despite running the fan? I didn’t carry spare Hall effect sensors, so parked that thought. I was convinced that it was something to do with the E10 fuel and (since the NTR in 18) I carried a spare fuel filter. STOP!!!! Always start simple, I hit the starter and could hear the starter motor churning away but nothing else. I couldn’t hear the whine of the fuel pump…but that’s said, I couldn’t really hear much at all due to the noise of the passing traffic (I have an app on my phone that measures noise - it recorded a steady 85dBA i.e. the noise level normally associated with using power tools). Fuses. Had a fuse blown and taken away power from the fuel pump - that would certainly match the symptoms? I carry a box of spare fuses…but didn’t have a multimeter with me so couldn’t check the old fuses for continuity (or check for voltage). Bugger - I meant to pack my multimeter but had forgotten it. Eejit! The fuses all “visually” looked OK but looks can be deceptive so I changed all fuses (yes I know that there are only 2 that support the fuel pump) with brand new ones. Still nothing (I later checked the old fuses at home and they were all good). I checked the fuel tank electrical connector - again, I know that this 4 pin connector can be the source of endless woes. It looked OK, and the pins were clean and seemed to fit snuggly in the socket. I squirted some contact cleaner over it for good measure and reconnected it. Pressed the starter button, starter motor ran but still nothing apparent from the fuel pump. My unhelpful other self was constantly nagging me to change the fuel filter - that’s mechanical not electrical I kept telling myself. However, it was worth a look in the fuel tank. Cautiously, with an eye on approaching traffic, I opened the fuel tank. Definitely about ¾ of a tank of fuel in there. I removed the filler cap to give me better access. All the hoses were where they should be and the fuel pump wires looked secure and undamaged. I put my ear to the now open fuel tank and pressed the starter button again - definitely silence from the fuel pump. This was definitely an electrical issue with either the pump or the supplies to it. Leave the fuel filter alone!! I buttoned up the tank.

Right think electrics! I called up the K100 Forum on my phone and looked for wiring diagrams and relay box layout pictures. Damn, I love this forum for accessibility to useful stuff when you need it. I dropped the left hand side fairing panel so I could take the fuel tank off. Bugger - no flat blade screwdriver in my tool kit. I managed to remove one fuel hose with a spanner (the lower end is more accessible) and that allowed me to lift the fuel tank enough to access the relay box. I replaced the fuel pump relay with one of my come in handy spares. Still the fuel pump would not run.
Without a multimeter, my roadside diagnostics and repair by random replacement was exhausted. Time for a breakdown truck. I called the RAC (Royal Automobile Club) breakdown services (part of my bike insurance package). Have you ever tried holding a phone call at the side of a busy motorway? Bloody hard it is, I can tell you. The operator probably wondered why I was shouting - just a natural reaction…if they sound faint, I must sound faint, so need to increase my volume and shout! Eventually, (they hung up on me first time through) I got through to an operator and explained my predicament. I followed their instructions by text to send my exact location to them and listened patiently to the helpful but bleeding obvious instructions how to stay safe at the side of a motorway. That call was made at 1335…about 1.5 hours after I had left home (30 miles away). 

I stood by my bike, looking hopefully for the breakdown truck rushing to my assistance. The sun was shining, it was lovely and warm and apart from the constant road noise, I was in good spirits. I left the side fairing panel off. No point putting it back on. My plan of action was to get recovered to home. Take the fuel tank off Heidi (she is off road and untaxed at the moment and I had carefully drained her fuel tank when laying her up for a long rest), stick it on Gretel and see what happens. If the fuel pump runs, then I can confidently rule out any deep electrical issues with Gretel and know that it is a problem with the fuel pump itself. If it doesn’t, then I’m buggered for the RTTW!
I texted my sister and brother in law who I was meeting at the hotel and explained my issue. I reassured them that I would get there - even if it meant I had to drive the car up…I had registered for them too and had the wrist bands that they needed for entry! I waited a little longer. After an hour of waiting, I got a text from a breakdown recovery contractor saying that they had been given my job and would be with me within the next 480 minutes. WTF number 2!! I couldn’t even comprehend what 480 minutes meant in the real world and had to use my calculator on my phone to converted it to sensible units. 8 hours!!!!!! I replied to the text asking them if they were seriously saying I had to sit by the side of a busy motorway until 2230. Irritatingly, they had texted from one of those numbers that you cant reply to and I just got a “failed to send” message which did nothing to improve my darkening mood. I then got a message from the RAC at 1437 saying that they were sending one of their trusted partners to rescue me…I tried to reply to that message too - “failed to deliver”. Another hour passed, 15:31 RAC text “Sorry if you’re still waiting, we’re very busy but trusted partner will be with you soon”. Aggggghhhhh!!!! Right, if I can’t respond to their stupid messages - I’ll call therm again. Went through the tedious breakdown reporting process again and explained that I had been waiting since 1330 and had been told that it could be up to 8 hours (from 1430). Yes, I know there was a bit of an issue with gas stations running out of fuel (lack of tanker drivers allegedly and media induced panic buying by the stupid general public), yes I expected that would result in more breakdowns as people drove around until they ran out of fuel, and yes I know that response times are likely to be longer that the normal “with you within an hour” due to covid and driver shortage excuses…but 8 hours - seriously!!!??? The nice lady at the end of the phone apologised, cancelled the contractor that had been assigned and said she would try an get someone quicker.  I hung up and waited…1615 RAC text “the special intervention team are now here to help you” - hurrah. I gave up looking up the road for the breakdown truck. The sun had dipped behind the motorway embankment and the air was getting distinctly chilly. I put my jacket back on and helmet too, made myself a nest amongst the brambles on the embankment and settled down to play Scrabble on my iPad. 


I watched as a low loader rumbled along the hard shoulder and missed the bike by a couple of feet. I texted my sister to reassure her that I still would get there. She said I should play dead and the police might stop to help me…nothing they could do, of course, and 2 patrol cars had already given me a stiff ignoring. Generally being ignored by the police is not a bad thing! I played dead anyway…perhaps too convincingly as a buzzard started circling above me and three magpies came closer to see if they could have a tasty free meal. 

Finally, just after 1730 (breakdown plus 4.5 hours) a breakdown truck arrived. No point getting grumpy with him, and 4.5 hours was way better than 10 hours! I explained the problem and we agreed the only option was to take me home. Gretel was rolled up onto the flatbed and we were on our way - home!

About an hour later I was home and thanking the recovery driver for his help as we unloaded Gretel.
As the bike was well and truly cold by now, I pressed the starter button one more time (if the Hall Effect Sensors had gone duff then they should work on the cold engine) - deafening silence from the fuel pump. I removed Gretel’s fuel tank and replaced it with Heidi’s…tentatively, I pressed the starter button again and yes, heard the familiar whine of the fuel pump. I decanted fuel from Gretel’s tank into Heidi’s and pressed the starter again - the engine roared into life. I replaced the fairing, knee pad and glove box and decanted the rest of the fuel into the new tank. I remembered to put my multimeter in my top box - just in case! By 2000 I was ready to go and set off up the road for the second time that day. No problem with being too early for the hotel check in now - in fact I had asked my sister to tell reception that I would be late and to expect a late check in…but I was coming!! However, I now didn’t have enough fuel to make the journey so would need to find fuel on route…that could be a problem with so many forecourts closed. My nearest supermarket was out. The motorways were much quieter now and traffic flowed freely as I rode quickly into the night. Motorway signs warned that several service stations ahead had no fuel. I opted for one of the earlier ones on route - no point riding until I was low and hoping to find somewhere open. I’d had enough breakdowns for one day. Result - lot’s of fuel. I filled the tank with premium high octane petrol, still having that niggling doubt about the crappy E10, and continued on my way. I reached my destination at 2200. A 2 hour ride that had taken 10 hours!

The RTTW was amazing, as always, even if the weather turned as forecasted and the light rain turned to persistent rain for the entire day. Bikes were marshalled from various starting points around the country, converging on the NMA. I started from Drayton Manor, the main start point and rode the 15 miles to the NMA in a convoy of about 900 bikes. Awesome experience. Flags proudly flying, beaming smile, and waving to the hundreds of people that lined the roadside and overpasses, followed by a poignant service of remembrance to the fallen since WW2. I had made it and was glad to have done so.







Hopefully, I will get to do the same again next year…without the breakdown though! 

I have still got to get the fuel pump out of Gretel’s tank and find out why it died. Maybe, 80k miles and 32+ years is the service life for these pumps? Maybe it does have something to do with the E10 fuel and possibly extra load on the pump causing its failure? I started to look, but getting at the fasteners holding the pump in place is not the easiest task, so I gave up and rode Gretel down to my sisters for a birthday party instead…without issue (apart from a centre stand bolt inexplicably shearing).

Any hints or tips for fuel pump removal and replacement gratefully received.

Are you absolutely sure the problem isn't the %^@*$# tank connector?  It might be worthwhile to check for the presence of 12v at the fuel pump motor's terminals when the start button is depressed. 

Having said that, the loss of power and gradual shutdown may indicate a failing pump or fuel filter.  Water in the tank is also a possibility.

Hi Paul,The pump removal is ,A easy peezzy or B a pain in the Bum, A squeeze the two clips together, gentle wiggle wiggle out comes pump  B,use a Tiwrap/Ziptie ready looped, slip over pump pull tight, to hold clips. Iuse WD40 to lubricate the rubber sleeve now Pull WIGGLE LIKE HELL  until it comes  free,

N/B Chinese pumps get rave reviews on this forum and cheap a well

moriarti wrote:Hi Paul,The pump removal is ,A easy peezzy or B a pain in the Bum, A squeeze the two clips together, gentle wiggle wiggle out comes pump  B,use a Tiwrap/Ziptie ready looped, slip over pump pull tight, to hold clips. Iuse WD40 to lubricate the rubber sleeve now Pull WIGGLE LIKE HELL  until it comes  free,

N/B Chinese pumps get rave reviews on this forum and cheap a well

Squeeze the two clips….????I need to go have a closer look. It looked to me like there was 4 (or more) M8 nuts to remove and I was cursing as even the most accessible one was a sod to get at. Maybe I should have taken a look at the Clymer manual first. Thanks - I’ll go in for another go this weekend.

Point-Seven-five wrote:Are you absolutely sure the problem isn't the %^@*$# tank connector?  It might be worthwhile to check for the presence of 12v at the fuel pump motor's terminals when the start button is depressed. 

Having said that, the loss of power and gradual shutdown may indicate a failing pump or fuel filter.  Water in the tank is also a possibility.

I’m absolutely sure that it is not the wiring loom end of the connector as Heidi’s tank plugged in and ran properly. It could be the part of the connector attached to the tank, but I’d be surprised as unplugging, de-oxing and much wiggling didn’t bring it back to life. Also, would be unusual to suddenly fail when riding along on a smooth road (but not impossible). 

As said, I didn’t have my test meter with me at the time (checking for voltage at the pump terminals with starter pressed would have been high on my list of checks) and when I got home, I was just keen to whipwop the tank and get underway again pronto. However, I will check this coming weekend before I get stuck into removing the pump.

Fuel filter blocking and or water in the tank (I’ve never found any water in my tanks) would surely prevent fuel flow and engine running but I would have thought the pump would still run when the starter was pressed (it didn’t make a sound). More investigation required - thanks for your valuable suggestions.

If you look at the following you will see the two 'clips' that you have to press to remove the pump assembly.  https://www.euromotoelectrics.com/BMW-K-Fuel-Pump-Supporting-Ring-16-12-1-464-629-p/fp-576ring.htm

The nuts you refer to are to remove the rubber vibration damper: https://www.euromotoelectrics.com/BMW-K-Rubber-Vibration-Damper-16-12-1-464-628-p/fp-576damper.htm

Mike

mike d wrote:If you look at the following you will see the two 'clips' that you have to press to remove the pump assembly.  https://www.euromotoelectrics.com/BMW-K-Fuel-Pump-Supporting-Ring-16-12-1-464-629-p/fp-576ring.htm

The nuts you refer to are to remove the rubber vibration damper: https://www.euromotoelectrics.com/BMW-K-Rubber-Vibration-Damper-16-12-1-464-628-p/fp-576damper.htm

Mike

Cool - thanks Mike. Yes, those were the nuts I spied…5 of the critters, not 4…so would have been impossible to access them all with the pump in place. Glad I didn’t waste too much tome trying. Now to go and look for those two clips!

Born Again Eccentric wrote:

Point-Seven-five wrote:Are you absolutely sure the problem isn't the %^@*$# tank connector?  It might be worthwhile to check for the presence of 12v at the fuel pump motor's terminals when the start button is depressed. 

Having said that, the loss of power and gradual shutdown may indicate a failing pump or fuel filter.  Water in the tank is also a possibility.

I’m absolutely sure that it is not the wiring loom end of the connector as Heidi’s tank plugged in and ran properly. It could be the part of the connector attached to the tank, but I’d be surprised as unplugging, de-oxing and much wiggling didn’t bring it back to life. Also, would be unusual to suddenly fail when riding along on a smooth road (but not impossible). 

As said, I didn’t have my test meter with me at the time (checking for voltage at the pump terminals with starter pressed would have been high on my list of checks) and when I got home, I was just keen to whipwop the tank and get underway again pronto. However, I will check this coming weekend before I get stuck into removing the pump.

Fuel filter blocking and or water in the tank (I’ve never found any water in my tanks) would surely prevent fuel flow and engine running but I would have thought the pump would still run when the starter was pressed (it didn’t make a sound). More investigation required - thanks for your valuable suggestions.

Well I’ll blowed! Got the pump out (easily - so easy when you know how!!) connected 12V directly to the pump terminals (making sure I got the polarity correct) and the pump ran sweet as a sweet thing. 

With the wiring disconnected, tested for continuity between all pins on the plug and the yellow and black wires going to the pump in turn. Continuity good on the black wire (-ve) stuff all on the yellow (+ve). I guess there is a break somewhere on the positive supply between the plug and the pump terminal - need to do some more investigating but looks like you were right Point-Seven-five its probably, as you call it, that %^@*$#  plug!

Born Again Eccentric wrote:

moriarti wrote:Hi Paul,The pump removal is ,A easy peezzy or B a pain in the Bum, A squeeze the two clips together, gentle wiggle wiggle out comes pump  B,use a Tiwrap/Ziptie ready looped, slip over pump pull tight, to hold clips. Iuse WD40 to lubricate the rubber sleeve now Pull WIGGLE LIKE HELL  until it comes  free,

N/B Chinese pumps get rave reviews on this forum and cheap a well

Squeeze the two clips….????I need to go have a closer look. It looked to me like there was 4 (or more) M8 nuts to remove and I was cursing as even the most accessible one was a sod to get at. Maybe I should have taken a look at the Clymer manual first. Thanks - I’ll go in for another go this weekend.

Hey moriarti, you star! Pump removal was option A - easy easy. Squeeze, wiggle and the baby popped out!!

Born Again Eccentric wrote:

mike d wrote:If you look at the following you will see the two 'clips' that you have to press to remove the pump assembly.  https://www.euromotoelectrics.com/BMW-K-Fuel-Pump-Supporting-Ring-16-12-1-464-629-p/fp-576ring.htm

The nuts you refer to are to remove the rubber vibration damper: https://www.euromotoelectrics.com/BMW-K-Rubber-Vibration-Damper-16-12-1-464-628-p/fp-576damper.htm

Mike

Cool - thanks Mike. Yes, those were the nuts I spied…5 of the critters, not 4…so would have been impossible to access them all with the pump in place. Glad I didn’t waste too much tome trying. Now to go and look for those two clips!

A picture paints a thousand words! Once I knew what I was looking for…I found it easily and the whole lot, including damper and bolts lifted out. It was even worse than I thought though - 6x nuts/bolts!!! Nightmare averted!

Born Again Eccentric wrote:

Born Again Eccentric wrote:

Point-Seven-five wrote:Are you absolutely sure the problem isn't the %^@*$# tank connector?  It might be worthwhile to check for the presence of 12v at the fuel pump motor's terminals when the start button is depressed. 

Having said that, the loss of power and gradual shutdown may indicate a failing pump or fuel filter.  Water in the tank is also a possibility.

I’m absolutely sure that it is not the wiring loom end of the connector as Heidi’s tank plugged in and ran properly. It could be the part of the connector attached to the tank, but I’d be surprised as unplugging, de-oxing and much wiggling didn’t bring it back to life. Also, would be unusual to suddenly fail when riding along on a smooth road (but not impossible). 

As said, I didn’t have my test meter with me at the time (checking for voltage at the pump terminals with starter pressed would have been high on my list of checks) and when I got home, I was just keen to whipwop the tank and get underway again pronto. However, I will check this coming weekend before I get stuck into removing the pump.

Fuel filter blocking and or water in the tank (I’ve never found any water in my tanks) would surely prevent fuel flow and engine running but I would have thought the pump would still run when the starter was pressed (it didn’t make a sound). More investigation required - thanks for your valuable suggestions.

Well I’ll blowed! Got the pump out (easily - so easy when you know how!!) connected 12V directly to the pump terminals (making sure I got the polarity correct) and the pump ran sweet as a sweet thing. 

With the wiring disconnected, tested for continuity between all pins on the plug and the yellow and black wires going to the pump in turn. Continuity good on the black wire (-ve) stuff all on the yellow (+ve). I guess there is a break somewhere on the positive supply between the plug and the pump terminal - need to do some more investigating but looks like you were right Point-Seven-five its probably, as you call it, that %^@*$#  plug!

Welcome to the International Brotherhood of the Victims of K Bike Tank Connectors.  You have successfully completed your initiation and as such are entitled to all privileges that pertain(whatever they may be).  

All my problems vanished as soon as I replaced that plug ! It's been 4 months and around 3000 miles since that day without any problems at all !

I tried Deoxit a couple of times but when it failed again out the front of Jaycar  after buying the new connector I took it as a sign. Since fitting the waterproof Duratech connector in Dec 2017 and it hasn't missed a beat.
Regards Martin.

As usual, I think I took the difficult way. I punched out the OEM pins and crimped on a set of Molex 0.093" series female pins which are too big. Yes, I knew they would be! . Once the pins were in I poked around with a small screwdriver until I had folded over the sides and made them look like roll pins. Good and tight and now it can be a bit of a bugger to disconnect the plug!

Happens to the best of us Paul. At least when my K75 did it I was at the Irish Pub at Boorowa.
Pulled up on the footpath under the pub verandah, booked into the pub, food and beers then bed. Came downstairs next morning, loaded up, pressed starter - nothing (but being a good sparky I had my multimeter).
Problem located in the female connectors of fuel pump plug, small pointed blade on multi tool rolled the socket to a smaller diameter and away we went.

Glad you were still able to make the Remembrance Day.

Cheers

I have on each K gone at those plug connectors to improve the connection as my RT one time 'educated' me on it., but thinking it may be a good idea to have a tank end replacement just in case. There is a box in my shed that has a 52 and 43mm pump, filter and all in tank stuff etc sitting in it....just in case.... but not the electrical bit.

Dai wrote:As usual, I think I took the difficult way. I punched out the OEM pins and crimped on a set of Molex 0.093" series female pins which are too big. Yes, I knew they would be! . Once the pins were in I poked around with a small screwdriver until I had folded over the sides and made them look like roll pins. Good and tight and now it can be a bit of a bugger to disconnect the plug!

I here was me hoping that you would leap into the conversation Dai and say…I changed my fuel pump connecter with xxxxx from yyyyy and it has been perfect ever since! I don’t think I’ll use your solution but I have seen a waterproof 4 pin connector (male/female) that looks suitable from RS Components. Might check out my local store at the weekend. Didn’t like the price tag much (£25) for the one rated at 30A and its a bit chunky but I’m not sure if the 5A version (£13) would be heavy enough duty. The fuel pump fuses is rated at 7.5A and generally the fuse is supposed to be the weak link in the circuit not the plug/socket. I know I don’t need a 30A current capacity but I don’t want to melt the smaller one either. 

Any idea what the starting current and running current of the fuel pump is? I did a little experiment and it suggested that the max starting current was about 2.6 A DC, with the running current considerably less. So perhaps the 5A connector would be adequate after all?

MartinW wrote:I tried Deoxit a couple of times but when it failed again out the front of Jaycar  after buying the new connector I took it as a sign. Since fitting the waterproof Duratech connector in Dec 2017 and it hasn't missed a beat.
Regards Martin.

Thanks MartinW - I had a look for Duratech connectors on line in the UK but couldn’t find any. Got a RS component 4 pin connector in mind at the moment. Just can’t decide on current rating (as per reply to Dai).

Gaz wrote:Happens to the best of us Paul. At least when my K75 did it I was at the Irish Pub at Boorowa.
Pulled up on the footpath under the pub verandah, booked into the pub, food and beers then bed. Came downstairs next morning, loaded up, pressed starter - nothing (but being a good sparky I had my multimeter).
Problem located in the female connectors of fuel pump plug, small pointed blade on multi tool rolled the socket to a smaller diameter and away we went.

Glad you were still able to make the Remembrance Day.

Cheers

If I had made it to the pub before breaking down Gaz, I would have been quite happy! The verge of the M5 motorway is not quite so relaxing. I wasn’t a good sparky and I was kicking myself for forgetting the multimeter. My problem is definitely on the male plug to fuel pump wiring side. Having disconnected the wiring from the pump, where the +ve supply resistance should be <0.1 ohm (i.e. just the resistance of the copper wire), I am getting 400 ohms. This suggests to me that there isn’t a physical break in the wire but a high resistance joint somewhere. I just destroyed the male plug to see if the high resistance was in there due to moisture ingress/corrosion etc.…it wasn’t!! But, I was going to replace the plug anyway. 

To add confusion the wires from the plug to the tank are coloured Brown, Green, White and Yellow. The wire from the fuel sender unit to the fuel pump are yellow (+ve) and black (-ve) (you can see the yellow and black wires in the fuel sender pictures on the forum tech pages). So, if it wasn’t the plug…then it has to be the junction at the fuel sender unit. More disassembly required!!

92KK 84WW Olaf wrote:I have on each K gone at those plug connectors to improve the connection as my RT one time 'educated' me on it., but thinking it may be a good idea to have a tank end replacement just in case. There is a box in my shed that has a 52 and 43mm pump, filter and all in tank stuff etc sitting in it....just in case.... but not the electrical bit.

I’m beginning to forgive the connector - just as I have forgiven the fuel pump! More investigation required but the fuel sender unit is the next thing to be investigated (the pump power supply passes through it). 

One thing I have learnt is that having a box in the shed/garage with just in case stuff is not much use when away from said shed/garage. Once I was recovered to the shed/garage by the breakdown services, then those spares (in my case the entire fuel tank assembly was the quickest way to getting back on the road) were invaluable. 

I already carry quite a few spares on the bike…the trick is to carry the right ones! A complete spare fuel tank might be a bit cumbersome

Born Again Eccentric wrote:

MartinW wrote:I tried Deoxit a couple of times but when it failed again out the front of Jaycar  after buying the new connector I took it as a sign. Since fitting the waterproof Duratech connector in Dec 2017 and it hasn't missed a beat.
Regards Martin.

Thanks MartinW - I had a look for Duratech connectors on line in the UK but couldn’t find any. Got a RS component 4 pin connector in mind at the moment. Just can’t decide on current rating (as per reply to Dai).

I used one of these and it worked great
https://www.amazon.com/MCIGICM-Waterproof-Electrical-Automotive-Connectors/dp/B0829Y7TGS/ref=asc_df_B0829Y7TGS/?tag=hyprod-20&linkCode=df0&hvadid=459665449369&hvpos=&hvnetw=g&hvrand=1112038915813476605&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004511&hvtargid=pla-946404782148&psc=1

"I already carry quite a few spares on the bike…the trick is to carry the right ones! A complete spare fuel tank might be a bit cumbersome"


I put air horns on the bikes.....the compressor fits in front of the fairing pockets, mounted on one of the original horn supports. A spare pump could mount there behind either storage box. Spare fuel filter fits in the relay box.

Looks as though you have the issue resolved. I certainly share your pain and understand the frustrations.
If you remember my problem first appeared half way down a long hill with no traffic and in the company of other members of the Krew. Petrol soaked hands take a long time to recover as well.

As an experiment I fitted a $36.00 OEM copy pump from Aliexpress in July 2017. I kept my OEM one in the tail as a backup as I was told it would quickly fail. The pump has been subjected to multiple two and four day long high speed runs  at 40C plus temperatures with no problems. However I'm still carrying a spare on the theory that it's never a spare that you carry that fails.
Regards Martin.

Born Again Eccentric wrote:Any idea what the starting current and running current of the fuel pump is? I did a little experiment and it suggested that the max starting current was about 2.6 A DC, with the running current considerably less. So perhaps the 5A connector would be adequate after all?

That sounds about right. I really wouldn't expect the fuel pump to be a current hog. You said K100LT - we are talking about that damn connector forward and left of the tank? Yamaguzzi's suggestion would be okay for an RT with the flying lead out the backend of the tank. I have a literal drawer full of two, three, four, six and nine pin Duratech waterproof connectors; just don't ask why. It was for a long term project which has been somewhat derailed, so they're all there for other uses now. If you are talking about the flying lead then PM me and I'll send you one across.

yamaguzzi wrote:

Born Again Eccentric wrote:

MartinW wrote:I tried Deoxit a couple of times but when it failed again out the front of Jaycar  after buying the new connector I took it as a sign. Since fitting the waterproof Duratech connector in Dec 2017 and it hasn't missed a beat.
Regards Martin.

Thanks MartinW - I had a look for Duratech connectors on line in the UK but couldn’t find any. Got a RS component 4 pin connector in mind at the moment. Just can’t decide on current rating (as per reply to Dai).

I used one of these and it worked great
https://www.amazon.com/MCIGICM-Waterproof-Electrical-Automotive-Connectors/dp/B0829Y7TGS/ref=asc_df_B0829Y7TGS/?tag=hyprod-20&linkCode=df0&hvadid=459665449369&hvpos=&hvnetw=g&hvrand=1112038915813476605&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004511&hvtargid=pla-946404782148&psc=1

Yamaguzzi - that’s interesting…I saw these on Amazon and was very tempted until I read some of the reviews. A number of negative nellies out there were moaning that the clips were fragile. The price was certainly very reasonable but that got me siding with the -ve nellies and thinking that “you get what you pay for”. Glad to hear that you had a positive experience with them.

Dai wrote:

Born Again Eccentric wrote:Any idea what the starting current and running current of the fuel pump is? I did a little experiment and it suggested that the max starting current was about 2.6 A DC, with the running current considerably less. So perhaps the 5A connector would be adequate after all?

That sounds about right. I really wouldn't expect the fuel pump to be a current hog. You said K100LT - we are talking about that damn connector forward and left of the tank? Yamaguzzi's suggestion would be okay for an RT with the flying lead out the backend of the tank. I have a literal drawer full of two, three, four, six and nine pin Duratech waterproof connectors; just don't ask why. It was for a long term project which has been somewhat derailed, so they're all there for other uses now. If you are talking about the flying lead then PM me and I'll send you one across.

The lead is out of the back right hand side of the tank…both my LTs are 89/91 vintage and are the same. As far as I’m aware the RT and LT are pretty much the same bike, just with a few creature comforts added to justify the “Luxury” moniker. I’ll send you a PM as I am interested to see how the duratech connectors compare with the RS Components ones. Thanks Dai.

Stan wrote:Looks as though you have the issue resolved. I certainly share your pain and understand the frustrations.
If you remember my problem first appeared half way down a long hill with no traffic and in the company of other members of the Krew. Petrol soaked hands take a long time to recover as well.

I remember that day well Stan! You had no shortage of helpful advice - but it got you going again each time and we all learned something from the experience. 

Following my little episode…I stank of petrol for most of the weekend - some ingrained into my hands but most spilt on my bike trousers when rapidly decanting from the duff fuel tank to a container to transfer to the good tank. Normally, I would siphon it across safely and cleanly…but I was in a rush!

So a bit more investigation…

Took the fuel level sender unit out. Chopped the 4 pin plug off to positively confirm that there isn’t a short causing the dropped voltage at the fuel pump terminal. Negligible resistance between fuel pump terminal and live pin on through tank connector (0.1 ohm) but high resistance between through live pin on tank connector and green wire (live pin on 4 pin tank connector) - 2.7K Ohms.


Pulled the fuel level sender unit from my spare fuel tank and repeated the experiment. Negligible resistance between fuel pump terminal and live pin on through tank connector (0.1 ohm) and negligible resistance between through live pin on tank connector and green wire (live pin on 4 pin tank connector) (0.1 Ohm) and negligible resistance from green wire (plug) to fuel pump terminal. (0.1 Ohm).


Ergo - Gretel’s unit has an issue on the live wire. There doesn’t seem to be a way to change the wire - the through tank connector is a sealed unit for obvious reasons. A new fuel sender unit is £220 from motorworks…so I’ll put my good spare in Gretel’s tank for now, put a new plug on it and, hopefully, I’ll be back in business.

This is a quick schematic of the tank circuit.  



J1 is the connections to the fuel pump Green/White probably changes color inside the tank to Black, and Brown changes color to White inside of the tank.  J2 is the 4-pin tank connector. For the purposes of the pump, ignore the other circuitry and concentrate on Green/white and Brown.  For information, the switch represents the low fuel switch and the resistor represents the fuel level indicator.  These are independent circuits and have nothing to do with delivering current to the pump.

With the sender on the bench and not connected to anything, you should read near short circuit (0.1 ohm) between green/white on the tank connector and Black at the fuel pump.  You should read near short circuit between Brown on the tank connector and white at the fuel pump.  You should also read near shortt circuit between Brown on the tank connector and the metal body of the sender.  You should read open circuit (O.L.) between Brown and Green/white or Black.  You should read open circuit between green/white and white or Brown.  You should read open circuit between either black or white at the fuel pump and the other two wires (yellow and White) at the tank connector.

It's odd to get 2.7Kohms readings anywhere on this device. It might indicate broken insulation on a wire.

robmack wrote:This is a quick schematic of the tank circuit.  



J1 is the connections to the fuel pump Green/White probably changes color inside the tank to Black, and Brown changes color to White inside of the tank.  J2 is the 4-pin tank connector. For the purposes of the pump, ignore the other circuitry and concentrate on Green/white and Brown.  For information, the switch represents the low fuel switch and the resistor represents the fuel level indicator.  These are independent circuits and have nothing to do with delivering current to the pump.

With the sender on the bench and not connected to anything, you should read near short circuit (0.1 ohm) between green/white on the tank connector and Black at the fuel pump.  You should read near short circuit between Brown on the tank connector and white at the fuel pump.  You should also read near shortt circuit between Brown on the tank connector and the metal body of the sender.  You should read open circuit (O.L.) between Brown and Green/white or Black.  You should read open circuit between green/white and white or Brown.  You should read open circuit between either black or white at the fuel pump and the other two wires (yellow and White) at the tank connector.

It's odd to get 2.7Kohms readings anywhere on this device. It might indicate broken insulation on a wire.

Thanks Robmack - that’s the conclusion I came to. 

Still a bit odd as there is no indication of any damage to the outer insulation (wire between plug and through tank connector). As I am confident that the sender unit is duff, I’m now going to do a bit of destructive examination…carefully remove the wire outer sheath and see if there is any damage to the wire. I suspect that the failure may be within the through tank connector, although I am puzzled how a sealed unit like that could fail in service.

The wiring colouring may be different between US and EUR versions. The power supply and earth leads from the fuel level sender to the fuel pump, on all 3 of my bikes/spares, are yellow (+ve) and black (earth). As you say, the fuel sender unit only forms a junction for these two wires to attach to the green (+ve) and the brown (earth) wires from the plug and is otherwise independent. As you illustrate, the yellow and the white wires from the plug connect to the variable resistor in the fuel sensor. Nice little trick by BMW to have two yellow wires with completely different functions! Especially when you can only see the two ends of each yellow wire!!