Fuel Injector Circuit

[harveyrawn]

My 2002 R1150R just stopped running one day while on the road. Died like I had turned off the ignition. When i try to start it, the engine cranks, the fuel pump and regulator pass fuel through the lines, the Hall sensors and coil operate properly, and the plugs spark. The side stand, clutch switch and kill switch seem to operate properly.

The missing component seems to be lack of fuel delivered to the cylinders through the injectors. I tested the electric connectors to the solenoids at the injectors and found no voltage when trying to start the bike.

Although all the other circuits seem to be OK, I think that the motronic is just not signaling the injectors to operate. I've read several threads here about broken wires and am hopeful that someone has experience with this particular problem and can direct me to specific wires and/or connectors to check.

All help will be appreciated.

[harveyrawn]

Well, the previous post wasn't entirely accurate. I pulled the injectors and found that they do spray fuel when the engine is cranked. So they obviously are receiving signals from the motronic.

Which still leaves my basic problem. The engine cranks, the injectors deliver fuel, the plugs deliver spark, but it doesn't even fire, much less start and run. How can that be?

[kirby]

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[previousrz350]

Fuel pump failing? You might have fuel coming out of injectors but is it the right pressure? Have you inspected all wiring harnesses? Might have short to ground on fuel or ignition wiring. If it stopped suddenly while riding I suspect its a fuel pump failure or intermittent short to ground on fuel or ignition circuit. I am a nubee to this site but I work on commercial jets for a living and have seen some really strange stuff with electricity. Do a really good inspection of wiring.

[harveyrawn]

Yes, I pulled and grounded both plugs plus used an external spark tester.
Yes, I had the pump tested by a MC mechanic, then I checked the flow after the regulator at the return line.

The possibly intermittent ground seems like a possibility. Maybe some grounding is weakening either the intensity of the spark or the pressure produced by the pump.

[kirby]

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[harveyrawn]

Thanks, Mike. As I understand it, my '02 does not have stick coils, only the leads from the coil to the plugs. However, one or both leads could be bad. I'll try to check them out.

[kirby]

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[harveyrawn]

I find that cranking the engine with the handlebars at full right lock will produce occasional backfires, the only firing since it stopped running. That suggests that the anomaly is in wiring that is affected by handlebar movement. The ignition and kill switch circuits come to mind. I removed the offending front-end zip ties long ago, but maybe they did some damage that is showing up now. Does anyone have any specific suggestions about where and how to look? Electrical matters are not my forte.

[Sunbeemer]

Sounds like you're on the right track. I'd guess the wire to the kill switch on the right grip is broken, and it may look ok externally but be separated inside the insulation. You can probably feel where it is broken by flexing it back and forth and it will be flacid at the break.

[omg1010]

As said before if you have fuel, air and a spark the bike will fire up. It may be that don't get enough fuel which would most probably indicate a problem with the pump and/or the fuel filter. If you have symptoms when turning the handlebar left or right that indicates a problem with any of the wires on the lock or killswitch ...

Finding such an electrical gremlin is not easy because you would have to have room for search. You would have to measure each and every wire to narrow down the problem area.

Brgds
Oliver

[previousrz350]

Are you running yet?

[harveyrawn]

No, not running yet. A local independent BMW mechanic had it for a couple of days to check it out. He and I both thought that he might find a shorted circuit somewhere, maybe from a rat chewing on insulation, but he had no success.

Then I had the local BMW dealer use their computer to check the motronic's fault codes and all safety interlock switches. Not only did they not find any problems (other than it won't run), they returned the bike today without reinstalling the timing cover and spark plugs they had removed. Their "best guess" is a bad Hall sensor, even though it tests OK. They've reinforced my opinion of some dealers' service departments.

In a nutshell, all elements are present for the bike to start and run, except it doesn't, only giving an occasional backfire. The dealer thinks that, although the Hall sensor is triggering sparks at the plugs, it's sending the signals at the wrong time. Possible, I suppose. I'd like to find a spare one that works for a trial installation to test that theory.

[kirby]

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[harveyrawn]

Running again!

I re-examined the Hall sensor. Even though it had tested OK with and without heat earlier, I found considerable online commentary about the possibility of hidden wiring insulation damage. Sure enough, when I opened the outer casing of the cable, I found that the insulation on the individual wires right at their splices by the sensors had become brittle and had cracked. In fact, the insulation crumbled and fell away from the wires as I handled them. Apparently, the insulation used up to about 2001 did not hold up well in the heat it experienced being right next to the engine block. BMW (Bosch) upgraded the insulation in later years.

I bought a new Hall sensor with upgraded teflon insulation from Euro Motoelectrics ($224) and installed it today. The engine fired up on the first cycle and idles beautifully. I'll go riding tomorrow.

Thanks to those who expressed interest and provided guidance.

[sweatmark]

Harvey, good info & thanks for sharing the rest of the story. How about adding "Hall sensor" to the topic heading for future reference? This is an ongoing problem for R1150** owners.

[harveyrawn]

Harvey, good info & thanks for sharing the rest of the story. How about adding "Hall sensor" to the topic heading for future reference? This is an ongoing problem for R1150** owners.

Done.

[previousrz350]

It's almost always a wiring problem wih issues like you had. Glad you found it!