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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: FranK75 on June 27, 2015, 02:13:33 PM
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My 91 K75 starts but will not run. It starts and idles for maybe 1 second and dies. Occasionally I can get it to rev if I give it some throttle but I get frequent backfires through the air box and it will not run at idle. I took it to the Beemer dealer in Charleston last spring when it was doing the same thing. They said I had bad fuel and water in my fuel. They cleaned that up and it ran great for a few months last summer. This spring forget about it! Here is what Ive done so far:
Checked Compression All cyls are good ~ 120
Removed and cleaned out gas tank what are those crystals that form in there?
Installed a new fuel pump & filter pressure from pump is 90 psi
Fuel pressure at rail is 40 it does not go up to 60 psi on starting
Spark is good
Injectors are injecting
Fresh spark plugs
Removed airbox and cleaned temp and mass air sensors
Cleaned and retightened battery ground
Bike has been mostly garaged and I dont see much if any corrosion on electrical. I think my FI computer is good (not really sure how to test it). Aside from installing a new fuel pressure sensor I am baffled. Any advice is welcomed.
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Just in case you haven't found the answer in the last 7 months... sounds like you've checked the easy stuff except one: Firing order. Too obvious? Maybe - with a triple, if one is wrong, two are wrong and you've only got one cylinder firing. Easy to check
Next thing isn't so easy. Check the cam chain - maybe it's jumped a tooth, or is just way stretched.
Good luck!