1991 40PLRP will only run for 35 seconds!

[kamp5740]

I own a 1991 40PLRP that I have had since it was new and have never had any problems with it. Now ii runs for exactly 35 seconds and promptly shuts off like I turn off the ignition. I can restart it and it will run for another 35 seconds and then quit running again. This happens at idle and at full RPM. I am at a loss as to what to try. It seems that the 35 seconds is key to my problem, but I cannot understand why the engine shutting off after this exact time regardless of the RPM of the engine. Any suggestions?

[99yam40]

What all have you checked so far and how ?
Is it loosing spark or running out of fuel?

[kamp5740]

I origionally thought it was a fuel problem until I noticed the 35 second run time. I runs great for that amount of time and then just shuts off. It is losing spark and I have ruled out a ground problem due to the consistency of time and the lack of sputtering.

[99yam40]

I know that my 1999 C40TLRX has the Prime Start System and that it advances the timing during start up and holds it there for a little while before dropping back to the normal idle timing of 7 Deg ATDC. The CDI controls the the spark and timing with input from the pulser coils and charge coils.

If you are sure it is loosing spark then you need to start troubleshooting with the help of a manual for your motor and some specialized equipment (DVA meter,timing light,etc.)
Print Out This Guide
This may help you understand some of the troubleshooting ,but you will still need a manual to get the specs for your motor.

Does you motor have prime start or chokes on the carbs?
It sounds like the motor may have carb problems. I have never heard of a motor loosing spark after 35 seconds and then restarting again over and over.