My K100 project is now road legal and I've been riding it about.
Occasionally the fuel pump stops working (you can hear it) and the bike dies. It also sometimes won't prime when starting, but it's usually fine. It did this 4 times today, once when cold, the rest when warmed up. Last time it was hard to start.
I tried cleaning the connector under the tank with no difference.

Could this be the hall effect sensor or do they normally fail completely? Not sure where to start with this one!

If you are certain that the connections are good, you may have a problem with the FI relay. See location here (under the tank in the electrical tray).
It could also be the plug of the EFI relay.
Are you doing anything on the bike between the time it stops and the time it restarts?

This happen to my brother few years ago.
The pump stopped, he remove the gas tank checked everything and couldn't find anything wrong.
Put everything together and the bike restarted again.
The connector for the fuel plug (under the tank) was the culprit.
Even if the connectors are clean, they may not make a good connection.

CF

I''ll try giving them a more thorough clean up and see if it makes any difference, hopefully that's all it is.
A couple of times I've heard the pump go quiet then kick in before the bike dies, when it's died at speed I pressed the starter with the clutch in (no clocks so it's clutch in to start) until it fired up.
It's never died for long, just enough to cause panic!

Speedaddictedberk wrote:I''ll try giving them a more thorough clean up and see if it makes any difference, hopefully that's all it is.
A couple of times I've heard the pump go quiet then kick in before the bike dies, when it's died at speed I pressed the starter with the clutch in (no clocks so it's clutch in to start) until it fired up.
It's never died for long, just enough to cause panic!

Try to pinch the female connectors to get a better squeeze on them.

How much fuel is in your tank when this failure occurs?

I replaced the connector with a 4 pin plug with the spade type pins and have had no more trouble.
The OEM plugs are not a very good plug and probably are the most used plug on the bike and fail very frequently.

I'm just back from a trip round the West coast if Scotland on my other bike so can get into the garage again today.

It's cutting out when empty or full, I filled it and it pretended to be ok for a while before dying in the middle if no-where. Got it restarted and rode home.

I'll try crimping this plug first

Also have a look in this thread.

Ok, crimped the plug and it pretended to be fixed for about 5 mins.
Then I turned it off using the killswitch and it's refusing to restart. The pump has primed briefly a couple of times then just dies again.
Wiggled the fuses with no effect. Wiggled the plug and unplugged it a couple of times with no effect.

Check if you got power at fuse #6 when pushing the starter button and it refuses to start..........to narrow it down a bit.

posted this in another post from Badgerjim, not sure if an '85 is the same as my '84 but here it is any way....



I had the same issue with my cafe build.  replaced the plug on the cable end with one off an old C.B. radio microphone, it has the same configuration as well as a threaded knurled nut that screws over the tank gauge female fitting. It has worked now for a few years, never fallen off.

[url=http://search.jaycar.com.au/search?w=4 pin mic]http://search.jaycar.com.au/search?w=4%20pin%20mic%20plug&view=list[/url]

http://www.ebay.com.au/itm/NEW-MICROPHONE-PLUGS-4-PIN-MIC-CB-RADIO-HAM-27mhz-MIKE-/190417511542?pt=AU_Electronics_Radio_Equipment&hash=item2c55c4a476



Good luck.

Fuse 6 (2nd from the bottom?) gets power, but only .2v all the others get 12v

Interesting solution.  The screw fastening is certainly reliable.

I'd choose an AMP Superseal connector in this application.  These are secure, correctly rated for the load and water resistant to IP54.

Available from Ebay extremely cheaply (seller hiteche).  I bought a selection from 2-way to 6-way from this guy when customizing my motorcycle.

If you measure only 0,2 volts when you push the starter button, the problem is most likely that the relay don't close its contacts....
next step would be to remove the tank and measure in the relay socket.

Will do, I'm now in garden centre hell with the wife !

Speedaddictedberk wrote:Will do, I'm now in garden centre hell with the wife !

 

The injection relay you find at front/left in the relay box.
You could first put a finger on the relay and feel if the relay clicks
when you push the starter button.

With the relay removed, you should read in the socket:
Terminal 30: unswitced 12V+.
-----"---  86: 12V+ when ignition and kill switch on.
-----"---  85: ground, when pushing the starter button.

Home now, still scarred by a Saturday garden centre experience. Managed to get out of multiple garden centre visits just for a look.
Off to remove the cafe seat unit to allow access for tank removal. Tank is sadly full.

85 isn't going to ground, others are correct

Relay clicks when button is pressed

It's the ignition ECU behind the steering head that sends out the ground signal.
Which is based on signal from the starter button and one of the hall sensors.


EDIT: if the relay clicks, you certainly also must have ground at 85 when the button is pushed. This ground connection is the signal to the relay to close the contacts, which is the click you hear/feel.

Could measure at fuse #6 again, but before you mount back the relay check that the terminals is clean (both socket and relay) and that all contacts feels like they got a tight grip (between relay and socket).

Ok, tested it by connecting between 30 and 85 while set to voltage, it gets 12v when starter pressed.

So am I down to ECI or Hall effect sensors?

Speedaddictedberk wrote:So am I down to ECI or Hall effect sensors?

If the relay clicks when you push the starter button, ecu and hes is OK.
I have added info in my previous post.


I would suspect the relay itself, or the related connectors.

If the connection inside the relay was bad it would give the poor voltage and not fire up the fuel pump.
Can you open these or is replacement the best option

It can be opened, look in the bottom.....you see a notch at all four sides of the plastic housing.
(Yours maybe looks different...different manufacturers have been used during the years....early models did have a metal housing....but all can be opened).

Not impossible that you find one set (it should be double) of contacts burnt.


If it can be reused, probably, you have to judge the contacts.
Clean them with some fine emery paper, remove all traces of metal dust.....
preferably use compressed air, if available.

Ok pulled the relay and cleaned the contacts, also cleaned the pins.
Fuel pump is now working! Not sure if I've fixed it though because the bike won't start. May have fouled the plugs with fuel.
Battery is charging so I'll try again later!

Could it be the ignition switch causing the fuel pump to cut out? 

Have you tried jiggling the key to the right in the ignition while the bike is running to see if it cuts out, or to the left while trying to start it to see if the fuel pump kicks in?

When I opened mine up it had one of the four springs loose causing inconsistent operation.

I tried jiggling the key when it wouldn't start, hopefully it's the relay and all will be fine with some more swearing time

Got it turning over, pump pumping. Plugs fouled

Got the plugs out and cleaned, would only run on two.
Wiggled various cables and it ran well for a few secs, so wiggled them again with no effect.
Tried one last start up for the night and it's working perfectly. I have no idea what's changed but it seems happy enough.
I'll try to give it a good run to see if it's actually fixed or acting nice so it catches me out...

As it was firing at only two cylinders...I would guess it's ignition related....
as one coil feeds two cylinders.

Which two cylinders were firing or not firing. One coil serves no 1 and 4, the other fires 2 and 3. It is possible you have a bad connection at the coils so check these. Before going to ECU swap the coils to see if the same cylinders fire. If the problem tranfers to the other two cylinders then it looks like a coil problem. If it stays in the same 2 cylinders then you need to look elsewhere as in ECU etc

The weird thing is that it was running fine apart from occasional random stops caused by the fuel pump. I haven't changed anything apart from cleaning up the relay.
Hopefully it's now decided to work but time will tell!

Ok I think it's the plug on the ecu, it stopped again today but a quick wiggle of the plug fixed the issue.
I'll pull the ECu ANC clean all the contacts, then crimp them tighter.
Super dooper drunk just now as it's after 2am and I started drinking at 3pm. Shots bad, pints worse. May be some time before bike is sorted (certainly not this morning!)

Speedaddictedberk wrote:Ok I think it's the plug on the ecu, it stopped again today but a quick wiggle of the plug fixed the issue.

It should be a small metal tab/lip/tongue on the ECU which locks the connector.
You should hear a click when the connector is all the way home.

But sometimes this tab/lip/tongue is missing.....when to heavy tools have been used to open it.

Man I'm tired.
Yeah it's got the taxable but it's not what you'd call tight so the plug is tie wrapped to the ecu.
Think it may just be wear on the pins/sockets. I'll clean em up, and tighten the sockets slightly.

Ok cleaned up the ECU and it seems happier. I've tie wrapped the plug into the unit too.

Next odd one, connected rear aftermarket indicators with 23w bulbs in them and it blows the firmest straight away.
Jammed relay?

Actually think it's earthing through the stem of the new indicators, looks like they're usually bolted through plastic but I have them attached to the plate for the cafe seat.

I'll try again tomorrow once I have more fuses

Ok I now have a working bike!
Relay and ecu have fixed the running problems, and insulating the indicators has fixed the fuse blowing problem.
Thanks for the help

K100LT, 1992.
I definitely had an intermittent fuel pump. The fuel pump occasionally wouldn't cycle on start up. Occasionally the bike would cut out when in motion.

A very long story short.

I noticed that one of the male pins on the pump/sender connection to the main wiring loom was a black colour, the other three are a shiny finish. The connection I am here talking about is the brown earth/ground wire.
From this evidence I suspected an intermittent connection.
Action:
I bent a small diameter piece of copper wire, pushed the same into the female part of the connector and then clicked both parts of the connector back together (making a tighter fit).
The bike now fires up every time.
My next job is to replace this aged connector with one of those connectors that are pictured elsewhere in this thread.