1985 Yamaha 150 ignition problem

kerrymc1 · #1 October 26th, 2006, 11:39 PM

Engine starts and idols good. As soon as the RPMs are increased, engine starts to break up, shake, backfire via exhaust. Port side bank plugs and head very cool as if not firing properly. Compression good in all 6 cyl. Gas seems good, even tested using portable 6gal tank with fresh gas. Plugs all seem to be getting spark, just not sure if in time. Replaced CDI unit with known good, still same problem. Any suggestions?? thanks

JUSTINTIME · #2 October 27th, 2006, 03:22 AM

sounds like rpm reduction
any alarms going off?
check all sensors, u have the manual right?

Ray Neudecker · #3 October 27th, 2006, 09:14 AM

The classic signs of a fuel restriction. Many posts already on this subject.

kerrymc1 · #4 October 27th, 2006, 05:05 PM

Quote:

Originally Posted by JUSTINTIME

sounds like rpm reduction
any alarms going off?
check all sensors, u have the manual right?

kerrymc1 · #5 October 27th, 2006, 05:07 PM

no alarms going off. yes I have the manual and will check sensors. thanks

kerrymc1 · #6 October 27th, 2006, 05:09 PM

thanks, will check fuels lines again.