so, I just finished rebuilding the fuel pump on my 87 K75S.
the pump had stopped spinning in the tank and the tank was full of gunky not-so-goodness from the almost entirely dissolved damper unit. so I pulled the pump and figured I'd have a look-see instead of just trashing the thing.

I was inspired by this link (from the downloads page of this forum):
http://hrsbstaff.ednet.ns.ca/bvogel/K100/fuel_pump/index.html

anyway, I took it apart without incident and found *some* gunk - but not really all that much. certainly nothing like what was in those pictures. in fact, there was hardly any visible reason I could see why the pump had failed.

I cleaned everything up and put it all back together. the rotor was spinning easily on the shaft and I could rotate the mechanical pump parts without problem when I spun it by hand.

BUT - when I put it back together and tested it by just hooking up some leads I got... a little click and that's it.
no spinning, not even a strong clunk or seized-pump-type-noise.
just a weak little noise and no spin.

what could be the culprit??

I happened to have another bad pump here (i'm starting a collection) and I switched out the top piece, figuring maybe it's the brushes but I got the same result.
I suppose the brushes could be bad on both...

any ideas? I'm confused by this turn of events.

thanks!

b

no replies??

still mystified at why the pump doesn't spin... would love to hear from some experts about this.

Bob,
Save money and a headache. Go here to my share docs.http://www.4shared.com/account/dir/CDKNGc7N/sharing.html?&

Download the fuel pump doc. Anything else you want you can download.
Ajays

Thanks Ajays! I actually found your article a day or so ago and called some local race shops looking for any discarded pieces of fuel cell foam. happened to find a shop not too far away that has a piece about 12" x 5" x 5" which seemed more than enough. the good news is they only want about $10 for it!

so I'm going down there tomorrow and picking it up and then going to Autozone to buy the pump and then... ride the she-beast home? let's hope so!

I'll be sure and let you all know if I run into any problems.

thanks again,
b

PS - I am still mystified at why the pump I 'rebuilt' doesn't spin... it spun by hand before I put it all back in the casing... it doesn't really matter I guess but I'm still curious. just the way I'm built =7

Just to put it right. I did not write that article, I wish I could take credit but it is anothers glory I would not like to take.
By the way, if it ran in your hand OK would it be the elictric supply to the pump in the tank?...a thought.
Ajays

I would think there is too much resistance in the connectors due to dirt/gunk/whatever. There for not enough current reaches the pump to make it start. If you connect it directly. whilst fitted, does it run then?

bobthebob, what happened in the end here? I'm going to pull my new project fuel pump apart too, so wanted to know how you made out in the event I cannot resurrect my pump.

had a similar thing happen to me today ...bloody fuel pump siezed on me ...
the fault was quite dramatic .....cruising home then nothing .....the bloody thing just died .
i thought to get more fuel but that didnt help ...oh well lets go into diagnosis mode ....

after some inspection and testing i found that the voltage getting to the fuel pump was not all good ,,,,but after removing the pump and dissasembling ( on the side of the road )thunderstorms threatening )
i found the pump to be locked solid ....
i jumpered the power to the pump directly from the fuse assembly and found i was drawing huge amounts of current without rotation ...omg ....this sucks ...was the first thought to go through my head ....
in any case i dismantled the pump completly after removing it from the tank ....and found the mechanics of the pump proper to be at fault......additionally the high current had caused another fault on the "tank power cable" the positive had become intermittent high in conduction ....meaning that there was no way that even after i fixed the pump there was no power capable to make it work ....
what to do !!!! durring reassembly i found that the tolerancs for the rollers in the pump mech had changed ......without further tools to fix this... i thought to loosly ...( as good as i could get reinstall all the mechanics and motor stuff ....useing direct power outside the internal tank wiring to test my reassembly) ...so far so good ....but the male plug (pins side ) of the power connector had developed a high resistance to the connected cable ....luckily i was able to get it bent in the right way to provide an escape route home ....with the pump running fine ....but i know this will not last long ...this was stricktly ...emergency proceedures ....

ok so does any one know what is a suitable replacement pump ?

for the intermittent connector ..( i guess its about where the connection terminals are welded to the actuall wire (weak point electrically ) i will have to replace with an after market 4 pole connection ...sigh ....sad to have to modify ......oh well !!!!

http://www.4shared.com/account/dir/CDKNGc7N/sharing.html?&

Charlie99,
Go to my file sharing site and download the fuel pump word doc.
Ajays.

hi ajays ...yes did some reading in there ....erm ...after i posted last night .....and whilst that does apear to be a solution im not overly comfortable having a motor wizzing round inside a compress of foam ...but it has merit .
i was really hopeing that someone may have found a more similar sized pump body from another vehicle (not nessecerrily german manufacture= high price )
i guess ill have to try the efi/high performance type suppliers and come up with another solution.

btw ... i suspect that useing fuel with ethanol is the culprit of my disaster and i really should kick myself in the bum for doing that, as i usually always use premium (98 fuel). but i do have admit it was unavailable from any of the local service stations durring the last week (bloody floods)

im thinking that the ethanol additive has perished / swollen the rubber pipes in side the tank and some has picked up into the mechanism through the breather pipe attached to the filter at the botom of the pump body ( as it broke away as i was removing it)

so theres a lesson to be learned right there . dont use ethanol based products in old ....or should i say fragile fuel systems .

thanks for your help ajays your a "keeper" mate !!!

bob ...keep watching this thread i intend to disect the power feed cable to the tank and locate the failed power wire .

in my case i think that the load drawn by the siezed pump ....or is that siezing pump motor...exceeds the rating of the cable ...so it develops a "hot spot " and becomes non conductive. if i find it ill post up a pic for you , and hopefully a solution .
but to all my past experiences in such matters , i expect this to be easy to find ....just hard to display without butchering the moulded connector termination point and cable . but ill try.

but in your case i suspect that the armature / commutator (bit where the brushes connect to the actuall motor -brass bits ) may have become over heated by the high current durring the stall event , or the connection between the brushes and the power terminals to the pump has failed at one point, or infact the armature windings (enamel covered wire )itself has developed a hot spot and no longer is acting as an insulated conductor.

this is verified by checking te commutator/ motor armature for evidence of burning ( at the segments of the comutator and windings ) it may look black in spots .
there are books written on this subject and i dont profess to be a professional motor rewinder but these ideas might give you some insight to why the thing doesnt turn on the application of power .
of corse assuming that the brushes are correctly reinstalled (with suitable length still left in them) and sufficient presure from the springs to connect properlly .

when reassembling an electric brush type motor it is always good to lynish the brass bits a little (to remove the pitting of the sectors caused by the application of current through the brushes ) and checking that the sectors are in fact not touching one another (insulated).

hope this helps

I have seen K bikes converted to carbs of which I have a picture somewhere, but has anyone fitted an external pump for our bikes?

There was a pump for sale (our type) on e-bay went for £29.
Ajays.

Charlie,
Foam can be flameproof...or one could use wire cotton.

external pump .
hmm interesting idea ajays .....after doing some reading ...i have not found many pumps that will self prime and with a head height suck ability ....(lift to pump) the reason for saying this is the way the pipe routing internal to the tank is designed...most of the externals i have seen are generally high presure or higher flow types... for more delivery i guess ...read that as "hotting up . or higher performance, and after an existing pump .
to me the design of the "bosch" pumps in our bikes requires fuel around the feed area .(minor problems for us when fuel is low )...im thinking a diaphragm design would be the go ...but preasure out of them is limmited .

i have found some excelent alternatives for replacement ( well priced ((under $100au ))and same body size ) problem is there is a trade off between presure , flow and current ...nearly all the ones i have found are great for 4-6 bar presure and 300kw + worth of flow ..current = 6+ amps .. bigger is not always better.

so im looking for something that may fit a 1.3l (max ) car type replacement = good for 3 bar and 50-100kw max flow , current to be under 4 amps...(the original wiring looks like that could be handled ok ) and 2 " (52mm) body diameter


still looking here

please forgive my lack of investigation for a bit ...im mooving house

On the German forum there is a lot of discussion about THIS pump, which seems to fit all purposes (size of pump/size of wallet) ;-)

charlie99 wrote:ok so does any one know what is a suitable replacement pump ?

Hi there, in my experience, any electrical pump intented for a modern fuel injected engine of similar power, that can be fited into our tank, will do the job.
The pump itself is small, today pumps are not only of the bearing type (positive displacement) but also centrifugal and provide the flow and pressure required by our injectors, i´ve been runing with a generic pump the last 12000 kmts with no problems, I dont spect this pump to last as much as an original but I can replace it easily as can be found at any car spare shop for around 20USD.
Of course I had to weld some connectors and build and elastic support but that was easy with commercial connectors and some hot water hose por the support.
Best regards
JAP

nice find renez

good work jap i would be interested to see what exact model you used .....is there a link somewhere

what concerns me is the flow rate and current most of all ..mechanics are purdy easy ...
cheers

Nice find Rene

I was on the manufacturer site and found that this pump delivers only 3 bars of pressure (43.5PSI). The original BMW/Bosh pump delivers 4.5 bars (or 65 PSI), but the pressure drops down to 36 PSI with the relief valve.
The DKK pump is powerful enough to be installed on a K100 bike.

charlie99 wrote:good work jap i would be interested to see what exact model you used .....is there a link somewhere

what concerns me is the flow rate and current most of all ..mechanics are purdy easy ...
cheers

I dont remember what I used, but the pump I replaced wasn´t the original, it was a Ford F1DU (there are more numbers on it but I guess thas the part number), this one is rated 60lb/hr at 3.1bar, as our injectors are rated 12.65lb/hr at 2.5 bar the numbers concour (and the bike was runing very well) and those were used to select the new pump and the new injectors (Standart FJ27 as sugested at http://www.ibmwr.org/otech/partsubs.shtml#BMWinjectors).
With this combination I´m getting 17km/lt at 140km/h.
Hope this can help
Best regads
JAP

Bert and other readers; my understanding is that the pump comes with a pressure regulator fitted that will set the pressure at 3 Bar (the dome shaped thingy on to of the pump). If one uses this pump the regulator of the pump is to be removed, which will improve the flow and I'm sure there's an internal relief set at more than 3 Bar, so it should work. It definitely should get you home and for the money a great spare to have.

If this pump doesn't have an internal fuel pressure relief valve (PRV), the external one has to stay to compensate. The Bosch pump provides 4.5 bars and the pressure is dropped down at the external PRV (on the back of the throttle body). The Bosch one has also a built in one way valve, and this after market one may have it built in with the PRV.
As this pump is a replacement for a 3.6L engine, it should provide plenty of flow for the K100.
Here is a detail of the internal Bosch pump:

charlie99 wrote:
ok so does any one know what is a suitable replacement pump ?

Hi there, take a look at this
Here: http://www.ibmwr.org/ktech/fuel-pump-install.shtml
Best regards
JAP

thanks jap .....good write up

i think i found a solution ......

i looked up my car ...cause its over 430000 klm old and supremely reliable ...to my surprise it specs a 51mm fuel pump ....current draw about 3.8 amps ....suitable fuel presure and about the right flow ...woohooo

so i got one after a couple of weeks from a much younger vehicle ...only 150000 on the clock ...so i figure ive got lots of hours running left in it

pic alongside the bosch unit


what i thought to do ....because of the slight diference in diameters

first make a slight cutout to hold some form of clamp ...


then i thought to use a stainless cv boot clamp as the holding mechanism ...cause its in fuel all the time

um sorry about the cold beer in the pic ......reward for a little later grin

i also thought to use a little bracket out of the satinless to act as a height retainer ...and anti swivel device ...cute huh ?

finished assembly ready for breather tube and insertion into the tank

but that has to happen tomorrow .....the pipe for the breather was too thick to be of use ...so a thiner version has to be sought ...

more to come ...results

I don't like the sound of having to use a smaller bore hose. Litre per Min flow is important...do you think it will cope with high speeds?
Hmm..maybe.
Ajays

oops maybe i should have been more speciafic ajays ...the fuel hose i picked up as replacement for the one that withered away was way to thick walled to go around the curly bits of the support bracket housing hole inside the tank ...still looking for 8 mm inside bore but not 16 mm outside ...the stuff i got was supreeme presure hose... looking for 12 mm outside ... after all it is just the breather hose to the top of the tank. the fuel feed is all 8mm id as usuall .


btw the pump i got is for a 1.6 litre car 100 kw ...quite capable for 2l/per min ...at 36 psi ...um 250 kpa and more ...funny the fuel presure regulator in the rolla is the same specs as the bmw ....i guess thats the technology used back then.

giggle

the rolla does 179 kph in 4th before redline at 7500 then theres overdrive etc ( opps verified on dyno ..dont wantcha to think im a lead foot ) grin

Hi Charlie,
Just make sure the fuel hose is rated for immersion in fuel, most fuel hose isn't and will break down rapidly if the outer jacket is immersed in fuel, with ordinary fuel hose only the inside is rated for immersion strangely enough.
Regards,
Jeremy

Wot's a 'rolla'?

Nice step by step with pictures.

I do have one question, though: does the beer label change to "WARM" after it sits in the sun a while?

thanks kbike ....in onto that ...i rebought some hose this morning no wonder it didnt fitt correctly after re-measuring the breather outlet it was 1/4 inch (6.3mm ) doh !!!
but i got full immersion rating stuff ..



oops sorry club c ...i really need to explain myself better ...rolla = corolla that little popular car made by toyota ....i think sold as many names throughout the americas ."sprinter" and many others ..i believe they have an affinity with gm over there just look for the "4a-xx" series motors



wanyne the cold is a reminder to the correct way to drink it ....giggles

i hear that in britain they drink it warm.....oeerrr ..shivers up my spine



so if it looks an easy fix the way i did it you too could look up the ae86 or ae92 series of fuel injected toyota origin cars ....this is the pump i used . as i said earlier i have over 430,000 killometers up on the car and this pump is a lot younger in mileage terms than that .

btw the beast lives again .....heading down the road in a little bit for more "extensive" "testing" wink wink

yay!!!!!!

Charlie,
You were fast to use Ned's emoticon....
Really good to share your find with us.
When you said that the pump came from a rolla, I assumed that it was Moto rola and I broke my phone in pieces to find the pump.
I am sure that 1/2 of the members of the forum will rush to the scrapyard to get a spare fuel pump.
Cheers

lol thanks bert ......
i feel a little ashamed that i wasnt able to buy the "real deal" after all im not sure how far many folks would concider bending the concept of "keeping the bike true to marque"

i can only offer what i thought was a wise choice, given my past experiences in reliability of other manufacturers... i was definatly not comfortable going down the "cheep chinese knokoff " replacement path .

btw ...after going for a short cruise around the streets, i think i have done good the old gal seems to run a little cooler and smoother ...acceleration 30kph-100kph seems smooth and not lacking in anything , in fact i think it has more get up and go ..
could this have been already a fault ..???
i gues the next thing i will find is that the fuel economy will go down hill quite suddenly and after reading other posts im guessing my fuel supply issues may have affected the great distance i was getting per tank , and the hot running i have been experiencing .

not having a k100 before it has been all objective observations to date . and im sure into the future .

What year is you corolla?
Toyota may have change the fuel pump over the years...
I was trying to check at on line scrapyards, but they are all asking for the age of the car.

</A>" border="0" />ok ....the models here range from 1985 and up bert ...my model was built 1989 ......through to 1992...you might be getting them before we do. so i would be taking off a year or so
but the clue is the engine .....mine is a "4a-ge" for anything with "4a-fe " or so would be about right dont forget ...fuel injected model ,there should be thousands of them ...just not sure what they were called over there

toyota ae 92 fx ..perhaps
early mr2 were the same vehicle



pic of mine


another pic from toronto


the classic rounded rear end of the fx hatch model

Thanks for the info.

In Canada, they are called corolla too. my wife owned one in 1965.

Here is what I found for aftermarket pumps. It's quite cheap!

omg that looks just like the one bert ....good find .....should i tell you i paid $25.00


yeah sorry about that ....i should also mention i picked it up from a self wreckers place ...took about 10 minutes to get it out

even at $50, it's a steal. (these ones are new)
You will notice that even Bosch has one but much cheaper than the one for BMW

just one other thing i should mention ....because the pump bracket in the tank is angled ...it would make sense to position the intake to the lowest level when installing it .