View Full Version : Yamaha 40 hp not running right need help

08-15-2006, 09:44 PM
i have a yamaha 40 hp that i recently rebuilt. I started it up and it ran for like 20 minutes but its missing.. like its running on 2 cylinders then sometimes 3. Then after about 20 minutes of run time it just cuts off. Its not the carbs because they been through very good by myself. The compression read 130 on all cylinders The coils arent bad. It may be the stator doing this but i really dont know. I need help badly please!!!

08-18-2006, 04:37 PM
they sell inline spark testers pick up 3 and watch what happends maybe you can pinpoint the cyl.
Check and see if you pinched a wire feeding one of the coils (not the plug wires) .
Does it get hot when it dies is it over heating

09-30-2006, 11:35 PM
could be the pulser also
get a spark board