Very strange (and dangerous) Electrical problem

[Artforge]

I have a 2000 M900ie and I've come accross a problem that I've actually encountered before.

Here's what happenned....

as I was riding down the road, all of a sudden my engine cut out. I pulled over and tried to restart the bike - no luck, as I switch the ignition to "off" I hear the fuel pump begin to pump, then I switch the bike to on, and the fuel pump goes off.

I disconnected the wiring to the fuel pump, and look around, everything seems okay - I reconnect it and the problem resumes....

Here's where it gets really strange...

So I disconnect the battery, and keep looking around (rubbed wires, disconnected fittings, etc..) all looks ok - but when I reconnect the battery - everything's fine again - for about 10 miles, when it does the same thing again - I repeat the above, and it works again.

This happened to me before, on the same bike, about a year ago. After looking over everything, I was stumped, I ended up replacing the wiring harness, and that fixed the problem - but a year later, it's back.

Since this has happened to me twice (with two different wiring harnesses) I have to assume it's a problem that someone's seen before.

If anyone can offer some insight, it would be greatly appreciated.

Thanks in advance,

Adam

[MotoCreations]

What was your fuel level in both situations?

Reason I ask is that if the fuel filter is somewhat blocked, it can creat extra load on the fuel pump -- thus running hotter.  Given the fuel pump uses gasoline as a coolant, it can actually overheat and stop running in this scenario.  Let it sit for a few minutes and it will cool off and work again and you typically thing it was something "electrical".

So two additional things to check.  1) in tank fuel filter; 2) in tank fuel pump.  If the pump itself is a problem, you can get an affordable alternative to the stock one via Chris / CA-Cycleworks instead.

[ducpainter]

In a totally different direction....

when it cut out was the headlamp still working or did you lose all power?

If all electrical power went away I'd replace the main relay under the seat.

[Artforge]

Thanks for the quick replies, to answer the thoughts you've raised:

The first time it occured (two days ago) the tank had about a half gallon in it, and it happened in less than 1/2 mile of riding, the second time (yesterday) the bike had a full tank, and I was about 5-10 miles out from the gas station (not much idling, so the engine shouldn't have been too hot).

As for the electrics, everything else was operating as normal, headlight went on, intrument lights were all as they should have been, starter fired as usual - it was just the fuel pump that ran when it shouldn't and didn't when it should - and I'm guessing the injection system (as even after the "off time" primed it, the engine wouldn't start).

I also doubt it was a heat issue, as the entire process of "fixing it" (both times) was done in about 5 mins, and didn't re-occur, after the bike heated up again.

I hope that helps offer some more insight.

-Adam

[Jethro]

.......as I switch the ignition to "off" I hear the fuel pump begin to pump, then I switch the bike to on, and the fuel pump goes off.

The fuel pump shouldn't start when ign is switched off so perhaps dodgy ign switch?

[Artforge]

The fuel pump shouldn't start when ign is switched off so perhaps dodgy ign switch?

Jethro,

I would have suspected that, if it wasn't that everything else points to it being a problem deeper than the switch (and that I was able to "fix" it temporarily by disconnecting the battery and re-connecting it). If it were just a problem with the ignition switch, I would expect it to be more consitent, and harder to "fix" without messing with the switch.

-Adam

[Duck-Stew]

If you haven't replaced the fuel filter recently then do it now.  It's cheap insurance and can cause odd problems.

That said, I've not heard of an ECU going hay-wire yet, but it can happen so perhaps your ECU has shorted internally.  PM 'brad black' and ask him directly.  Likely, he'll have an answer of worth.  You'll need to PM him directly as he doesn't frequent this board all that much and he doesn't look at every thread.

[brad black]

the fuel pump is controlled by the ecu.  the ecu earths the fuel pump relay earth wire and this activates the fuel pump relay, sending power to the pump.  the ecu runs the pump for a preset amount of time when you turn the key on (3 or 5 seconds or so, i forget), and then runs it again when it receives a signal from the rotation sensor.  it runs it as long as it receives a rotation sensor signal.

you need to diagnose when the problem exists.  a test light would be good.

does the tacho do anything funny?  a bad rotation sensor input or ecu fault with rotation sensing should see the tacho drop to zero or go wacky.

is the pump being fed power through the red wire when the key is turned off or is it coming back in the black wire?

is the fuel pump relay ok?  check if the power is coming out into the red wire when the pump runs at key off.

remove it and short the relay using a short jumper wire from terminals 30 (battery power) to 87 (pump).  this should tell you if the pump and electrical power side of things is ok.  the pump should run continuously.

check the pump relay earthing wire at the ecu.  you'll need a wiring diagram to work out which wire.  if the ecu is activating the pump at key off then it it'd be a bad ecu.  sort of sounds like it to me.

[DucatiBastard]

I had a problem recently which i eventually diagnosed as a bad ECU (fwd cylinder injector not firing with power getting to the injector).  I dropped my bike off at the shop today to have them fix it, i'll let you guys know when i find out, FWIW. 

[Jarvicious]

Given that the ecu controls the fuel pump, both at the time of ignition and after cranking the engine, I'd say it's unfortunately a prob with the ecu.  Someone with more internal knowledge than I please speak up, but judging by the fact that the problem is quite random in addition to the fact that the problem "resets" when you disconnect the power for a time, it looks like you have a bum ecu that randomly decides when the fuel pump should or shouldn't run.  Is the ecu capable of building an unhealthy charge over the duration of the bike operation that could cause intermittent firings like this?

[Duck-Stew]

One *could* re-wire the fuel pump relay so that the ECU isn't controlling it (providing that's the ONLY problem the ecu is experiencing...)

Could be wired to the bike's ON/OFF switch perhaps....  YMMV, and I have no FHE doing this but it should work just fine by my understanding of electrics on bikes.

[Howie]

One *could* re-wire the fuel pump relay so that the ECU isn't controlling it (providing that's the ONLY problem the ecu is experiencing...)

Could be wired to the bike's ON/OFF switch perhaps....  YMMV, and I have no FHE doing this but it should work just fine by my understanding of electrics on bikes.

That will wok, but the problem with that is as long as the key is on the pump will run.  This can be a safety issue. 

[Duck-Stew]

That will wok, but the problem with that is as long as the key is on the pump will run.  This can be a safety issue. 

Well, actually, the key would have to be 'on' as well as the engine off/on switch but yeah....could be a safety issue.  The owner/rider would have to know about this in advance and be aware of it.

[Capo]

One could wire an indicator lamp in the fuel pump circuit, that way if your problem happens again and the lamp is off, you have an ECU problem.
From the symptoms you describe, I doubt wether its a filter problem. Blocked filters first affect large throttle openings (weak mixture then insufficient fuel) this progresses downward as the filter condition worsens.