Fuel pump bad or is it the wiring that faulty

[bmwgsrider]

There is a brown, green/white, and blue/white wire. Brown I believe is ground, green/white I believe is positive as well as the blue/white wire is positive. I do not have a wiring diagram. I am not sure where the green/white and blue/white wire runs to. Three wires run to the fuel pump. I am trying to determine if the fuel pump is bad or if the wiring is bad as the bike will not start because the fuel pump is not kicking on.

I have the gas tank off and the connections disconnected. On the connection of the fuel tank... the brown is on top, green/white in the middle, and the blue/white wire is on the bottom. When the key is on... the connections on the bike side... the green/white wire has no juice. The blue/white wire is pulling 12 volts. The connection on the gas tank side, the blue/white wire has no juice as the fuel pump does not do anything... when you hook up juice to the green/white wire it turns on the fuel pump.

Does anyone know what is causing my problem to where the bike will not start? Would it be the fuel pump that is bad or is it in the wiring?

Any help would very much be appreciated! Thanks so much in advance.

[sweatmark]

Will guess prior to Clymer verification. Green/white is fuel pump, blue/white is tank level float circuit. If power to tank-side g/w wire started pump, then you have confirmed its operation. Question is why no 12volts to bike-side g/w wire when key on. Kill switch? Side stand? Fuel pump fuse? Or possibly problem with wire harness for that fuel pump circuit, though it would be first time reported here.

Good luck.

[Airman]

Can we assume you've checked the fuse ? I'll go look at my new Clymers manual after while and see if there's anything else in the circuit, there may be a circuit tied to the kill switch. Does the pump switch off after it pressurizes the line when you have it jumped ?

[bmwgsrider]

We did check the fuses. Fuses are okay. Did not let the fuel pump run long... for the most 10-15 seconds. Should we try to run the fuel pump longer?

[sweatmark]

No, you've shown that pump will run when supplied power. Problem appears to be the supply.

Quick experiment in the garage shows that side stand interrupts starter, not fuel pump. Kill switch DOES interrupt fuel pump, so check position and then check for possible short in wiring harness to RHS switch module.

[bmwgsrider]

Kill switch DOES interrupt fuel pump, so check position and then check for possible short in wiring harness to RHS switch module.

RHS switch module... do you mean the kill switch? Trying to understand what you are talking about. Thanks.

[sweatmark]

Right hand side switch that contains kill switch and start button. You might try wiggling that wire bundle over its length, looking for short that would impact fuel pump power circuit. Could also test continuity for the kill switch circuit at harness connector, where it attaches to main harness on front subfeame' since you've got tank off.

[sweatmark]

Posting messages from BlackBerry is fraught with errors.

[NoRRmad]

Particularly check the wires under the (too-tight) tie-wrap straps near the steering head.

[Sunbeemer]

The green wire with the white stripe comes from the fuel pump relay, which is the third black relay from the left at the front of the fuse box. You could try swapping it for the horn relay, which is the second black relay from the left to see if the pump comes on, but the horn fails to work. This would diagnose the relay as the culprit.

[bmwgsrider]

The green wire with the white stripe comes from the fuel pump relay, which is the third black relay from the left at the front of the fuse box. You could try swapping it for the horn relay, which is the second black relay from the left to see if the pump comes on, but the horn fails to work. This would diagnose the relay as the culprit.

The horn relay did not work for the fuel pump... but when I put the fuel pump relay on the horn. The horn worked.

Originally my ignition switch (key) got locked...steering head (front forks) Finally was able to unlock the key by using a lot of WD 40. After that, the bike wouldn't start. Could it be the ignition switch (key) causing problem?

Still trying to diagnose the problem and still not having any luck. Been busy with work... and have not had much time to diagnose problem.

I do not have any service and repair manual to this bike. Can anyone suggest which service and repair manual is the best?

Any more advice/help would be very much appreciated.

Thanks again in advance.

[Boxer]

Usually its something as simple as not having the fuel line QDs completely joined together. If those are partially disconnected the fuel pump will not operate. Make sure those are pushed together firmly, clicking as they join.

[bmwgsrider]

I understand about the QD's... I can double check that again as they do go together hard. It seems though I am not getting any electric to the fuel pump.

[Sunbeemer]

Chances are fair to middlin' that there is a broken wire under the headpost resulting from overly-tightened cable ties at the factory. This has been extensively documented in this forum, and Cyclerob posted a diagram of exactly which ties to cut, which are on the right side of the bike near the horn. You can try wiggling the wire loom in that area with the key on to see if you can get an intermittent whine out of the pump. If you do, then you know where the broken wire is and you can fix it.