Backfiring R1150RT

[wrealini]

My '04 R1150RT quit on me on the freeway several weeks ago, I found the fuel pump dead and the fuel filter clogged completely, I installed a new pump and filter and now my bike backfires in the air box(air cleaner).
I have replaced the timing sensor, the old one checked ok but I replaced it anyway, it still backfires. Does anybody have any suggestions?
The bike has only 35,000 miles on it.
Wally
(949) 466-6106
wrealini@hotmail.com

[DrPaul]

My '04 R1150RT quit on me on the freeway several weeks ago, I found the fuel pump dead and the fuel filter clogged completely, I installed a new pump and filter and now my bike backfires in the air box(air cleaner).
I have replaced the timing senson, the old one checked ok but I replaced it anyway, it still backfires. Does anybody have any suggestions?
The bike has only 35,000 miles on it.
Wally
(949) 466-6106
wrealini@hotmail.comSounds like a fuel injection or ignition timing problem. Was it backfiring before you messed with the HES? Does it backfire at random or only on decelleration? How does it run otherwise?

[wrealini]

It started to backfire when I replaced the fuel pump and filter. I could not start the motor because it was backfiring too much. I replaced the crankshaft positon sensor and now it will start but it won't idle due to the backfireing problem.
Could it have too much fuel pressure and leaking past the injectors?
Would clearing any faults cause the engine to run differently?

[PGlaves]

Go back to basics:

Check the timing with it running with a timing light. Hard to set, but easy to see doing it that way.

Next, check the spray pattern of the injectors.

Third - get a series in line spark plug tester. One with the glow bulb in the middle. Plug it in between the wire and the plug and crank/start the engine looking for regularity of spark.

Then, check for air leaks where the throttle bodies attach to the heads - both the spigots and the O rings between the spigots and the heads.

[DrPaul]

It started to backfire when I replaced the fuel pump and filter. I could not start the motor because it was backfiring too much. I replaced the crankshaft positon sensor and now it will start but it won't idle due to the backfireing problem.
Could it have too much fuel pressure and leaking past the injectors?
Would clearing any faults cause the engine to run differently?I can think of a few things that could go wrong on a fuel pump/fuel filter change:
1- flow through filter is bassackwards
2- polarity reversed to fuel pump (this happened to me once on a K75S!)
3- an internal fuel hose or tank vent/overflow line has come loose
4- Pump/filter/float plate reinstalled in wrong orientation
5- external fuel line quick disconnects are reversed (normally this can't happen unless the "gender" direction of one of the QDs has been altered)
6- A mishap reconnecting the electrics between bike and fuel tank
7- external tank vent and fuel overflow lines switched (are you still "canistered"?)
8- fuel contamination while tank was open
I do not think the fuel pump could produce enough pressure to force an injector nozzle open nor do I think fault code clearance is a factor. I'm not certain if/how any of these potential problems could cause your backfiring but it's worth checking. I'm sure others will offer other ideas.

[wrealini]

Thank you for all for replys
I have a lot to check but please keep the ideas coming.
Wally

[Sidmariner]

After completing a spline lube on my brothers 1200C late one evening he rolled the bike into the winter dark of my driveway and started it up. It immediately began backfiring.

Every time it did I noticed flames shooting out from under the air intake tube collars. It turns out we had forgotten to tighten them down on the cylinder head side. After a few quick turns with a screwdriver he started up and the backfiring was gone.

Occam's Razor applies: check the simple things first.

[wrealini]

Starting over today we first checked for a loose throttle body and found the left throttle body loose. After tightening it I started the machine with visions of a perfect idle. No such luck. It still backfires but it will idle about 750 RPM.

Next my son and I removed each injector connector (electric) one at a time and Eureka! There was no difference in the way the bike ran with the right side injector disconnected. Our next check was the measure the resistance of the coil on each injector and both checked the same so we can assume they are good. While checking the spray pattern on the right side again we discovered the fuel pump works great, as we had a little mishap of losing the fuel connection with the key on. Fuel everywhere!

Assuming that since we proved to have fuel being delivered to the right cylinder our next check was the ignition coil and Eureka! again. The coil measures only 7.5K ohms on the secondary. It should read about 15K according to the downloadable white sheets for oilhead ignition sensor repair on an affiliated web site. Next stop BMW Parts for a new coil.

[masonke]

......
Assuming that since we proved to have fuel being delivered to the right cylinder our next check was the ignition coil and Eureka! again. The coil measures only 7.5K ohms on the secondary. It should read about 15K according to the downloadable white sheets for oilhead ignition sensor repair on an affiliated web site. ...

Could you post the link to the web page? That would be a great piece of info to have.

Where do you check the resistance?

Thanks
Kevin

[wrealini]

Here is a link to the web index for similar items posted by hoosierbeemers.org

http://users.rcn.com/dehager/

Good luck, I would be careful preforming the replacement of the Hall Effect Sensors, a rivet tool needs to be homemade to peen the rivets. I have a machine shop available to me and I had difficulty riveting the new sensors in place. Keep it clean and solder the wires carefully, mine worked better than the new item from BMW.

I purchased my sensors from Newark:

http://www.newark.com/honeywell-s-c/2av54/hall-effect-magnetic-sensor/dp/96F1986

[wrealini]

I spent the day today working on the BMW with no good news to report.
Yesterday the crankshaft sensor arrived and my local cycle parts store called because the plugs arrived.

NOTE: For all those who have not changed plugs yet beware, the Dual Spark uses two different types and manufacturer of plugs.

The Upper plugs are:
NGK BKR7EKC-N
They are distinguishable by the size, 14mm Threads

The Lower Plugs are:
Bosch YR6LDE
Mostly available only from BMW Dealers (can be found over the net)
These Plugs are only 12mm Threads

So here we go, I first tested each ignition coil, there are three different ones on the dual spark. One large dual coil under the tank mounted in the frame that powers the two lower plugs, one each in each of the two cylinder head cover for each upper plug. All coils checked out OK both statically with an ohmmeter and with spark with the plugs removed and the injectors disconnected as I crank the motor. A note here is that the secondary of the dual coil (for lower plugs) measures 7.5K Ohms, about half recommended by another web site. However, the coil shows no sign of overheating by visual inspection and the spark is good at the plug.

My next step was to gap and install the new plugs. Don’t believe them when they tell you that new plugs are pre-gapped, mine measured 0.5mm out of the box and the book calls for 0.8mm for both upper and lower plugs. So I gapped them with a wire type spark plug gapping tool and a magnifying glass, required because of my age and need to see better.

Ready to start the bike and with a good feeling that this is going to be the cure, the bike started but it still runs on only on the left cylinder, about 750RPM. Now I started to narrow the field by swapping parts right to left. I tried swapping the injector nozzles, the upper coils, and finally the wiring to the lower coils. By swapping I wanted to see if the misfiring would crossover to the other cylinder, in each case the problem remained on the right side.

That leaves only the compression to check, since I don’t have a compression tester or a leakdown tester available today I cranked the bike over with the right plug removed and tried to keep the plughole covered with my long finger. When I removed the plug from the right side, I noticed it was gas fouled indicating the fuel is reaching the cylinder. Anyway I couldn’t hold back the compression, the bike started on the left cylinder and with great force it blew fuel/air mixture out quite a distance as I tried to cover the hold, in my opinion there is sufficient compression for the bike to run on the right cylinder.

[flars]

Silly question, but... since you had the tank off you could have caused the right side throttle cable to get hung up. This could cause all your symptoms because the cable would be holding the right butterfly slightly open.

[wrealini]

Thanks, I will check that tonight.
This is the best place for help, thank you all...

[keybuster324]

I had the exact same symptoms on my 94 R1100RS and it was the right side throttle cable had pulled out of the adjuster on the throttle body and it was holding the butterfly open.. I put it back into place and it started fine. I hope yours just this and not more serious.
It was someone on this board who helped me find my trouble, Good luck

[wrealini]

I checked the throttles today when I got home from work and Eureka!!!!

The Throttle cable pulled out from the adjustment nut on the right side throttle body. I put it back and checked for tightness on the cable and it all looked good. I started the bike and it now idles good and runs great.

Thanks again to all who helped.

Feel free to email for details if you are having similar problems.