1992 yamaha 4 stroke 9.9 idle problem

[nogimmies]

Engine starts then runs ok for 30sec to 1 min then starts to sputter and dies.
Wait 2-3 minutes and restart with same thing happening
Cleaned carb checked jets and passages
checked filter ,fuel pump
when I loosen the Electo thermal valve runs for a little while longer and dies again
Thinking it may be the valve but reistance checks ok.
Puzzled on this one.
Click it into gear and rev for a while and runs ,but dies at idle.

 

[CatTwentyTwo]

Re: 1992 yamaha 4 stroke 9.9 idle problem

One other check for the thermal valve is to remove it from the motor and connect the leads to a 12 volt battery. The needle should extend as it warms up, this closes the cold start enrichment jet.

 

[nogimmies]

Re: 1992 yamaha 4 stroke 9.9 idle problem

Needle did not move after on 12v for 3 minutes.
Checked again with meter and circuit is bad
Orderd a new electrothermal valve unit and some other parts.
Hopefully this will solve the problem.
Thanks for your input
nogimmies

 

[nogimmies]

Re: 1992 yamaha 4 stroke 9.9 idle problem

Got it running without the ordered parts.
After all that fuss I found that the Air idle screw needed to be backed out another 1.5 turns to about 5.5 turns total vs 2-4 as manual calls for.
As soon as the thermovalve does its thing the engine would quit.
Not now
Engine runs like a Jap/swiss watch.
Now for my next endeavor
Changing the 9.9 to a 15 with some new jets.
I'll post my results.
nogimmies