Need help 1987 40etlh yamaha

[Jmyers344]

The boat has been sitting for a year I cleaned the carbs, changed the plugs, fresh fuel, new water impeller motor fired right up started every other day for a week for about 15 minutes ran like it was brand new then I finally decided to take it out I launched it at the ramp the motor fired then stalled, fired it again then stalled then it wouldn't fire again after cranking it I brought it home and noticed the electric choke pin fell off so I fixed that and still nothing, I have spark and fuel and it still will not start any suggestions ?

 

[Capt Ken]

Re: Need help 1987 40etlh yamaha

Fire, fuel and air. You either have not enough of some or too much of others

 

[Jmyers344]

Re: Need help 1987 40etlh yamaha

I just cleaned carbs out again and still noting is there any safety feature that would stop the engine from running besides the kill switch?

 

[99yam40]

Re: Need help 1987 40etlh yamaha

Compression, spark, and timing are all easy to test.
If that is all good then you are left with fuel to air ratio keeping cylinders from firing

 

[Jmyers344]

Re: Need help 1987 40etlh yamaha

Just did a compression test I have 60 in the top 30 in the middle and 60 in the bottom I guess this solves the problem.

 

[99yam40]

Re: Need help 1987 40etlh yamaha

Seems mighty low. Stuck rings or damaged cylinders/pistons
I hope you have been using 2 stroke oil with the gas
I would get a different gauge or test a different motor with the gauge you have, just to make sure what reading you are getting are correct.

 

[Jmyers344]

Re: Need help 1987 40etlh yamaha

Yes I have been using 2 stroke oil I pulled the flywheel today and the woodruff key the is on the shaft to the flywheel was sheared. I ordered the part today so hopefully this will be the fix.

 

[99yam40]

Re: Need help 1987 40etlh yamaha

sheared key will not change compression just makes it fire at wrong time