Hi,

I have a 2001 929 that has set for a couple of years, but started every now and then. Got the bike out, changed oil, coolant, etc. After filling the radiator and running the bike to purge the air out for about ten minutes. All was fine, and bike was running great. Shut off bike to let it cool down. Now only runs on cylinders 2 and 3. I had not touched ANYTHING! Did add sea foam to gas to clean things out.

I've drained the gas, put new in, and changed the spark plugs. Still only running on 2&3. Bike has seperate coils for each cylinder. What is common to cylinders 1&4???

I'm looking for help, please.




Ric

 

I can't say what's common between cylinder 1&4, but if it was me, I'd change the coils (1<->2 & 3<->4) if the problem tracks the changes then you have 2 bad coils. next i'd think it was clogged injectors in 1 & 4. pull em and clean or replace.

also the voltage regulator/rectifiers on these bikes have been problematic for many in the past. it may be a good idea to get it running off those 2 good cylinders and see if they system is maintaining the proper supply voltage going into the coils. this probably won't be the cause, just something that came to mind.

 

Thanks for the post. After new plugs, I checked the fuel pressure regulator. With the fuel pump on, fuel pours out of the vacuum side of the regulator. I have another on order and will post what happens.


Ric

 

You definitely found the problem, Ric. I bought a 2003 954 a few weeks ago that was wrecked and has been sitting for 5 years. I went thru the same EXACT scenario that you did. I replaced the fuel pressure regulator and voila, the bike is running like a champ again. It seems that the rubber diagphram in the regulator gets brittle after sitting for a few years and breaks, letting fuel run straight the rail and thru the vacuum side as you found.

What a coincidence. I was just trolling the threads on here looking to thank the guy that gave me the idea to check the FPR. I was just about to give up on the bike when I ran across that thread on here.