1989 50 hp yamaha won't idle more than 15 seconds

[ethan 33]

1989 50hp yamaha pro won't idle more than 15 seconds then dies but starts right back up at the turn of the key. Checked for water in fuel,none. Took carbs off and cleaned they were spotless, same issue. isolated control box from the engine same problem. Spark is great. Boat run's great at any speed above idle. Put oil in the gas thinking the injection system was not working right at idle. This is a 3 cyl with 3 carbs. Primer bulb never goes flat always stays hard. Choked it when it started to die made know difference, tank is vented properly. Any suggestions would be appreciated iam leaning toward's the fuel pump.

 

[soco_69_69]

Re: 1989 50 hp yamaha won't idle more than 15 seconds

Ethan 33 i have the same exact engine with the same problem. I have taken the fuel pump off and rebuilt it and it is doing the same thing. someone told me a back thermostat could do it but doesnt explain why its only at idle that it stalls. only suggestions i have so if you come up with anything else please share.

 

[99yam40]

Re: 1989 50 hp yamaha won't idle more than 15 seconds

Probably have clogged low speed / idle jets if it will run otherwise. you need to take carbs completely apart and clean all passages and jets.

 

[patrick4266]

Re: 1989 50 hp yamaha won't idle more than 15 seconds

I bought a boat around november with a 1988 pro50 although the motor title says 1989. Anyway I had the same problem. I adjusted the timing, just a bit, and now it idles fine, as soon as it warms up a little.