Yamaha 150 prov troubles

[Snoopy]

I have a 86' Yamaha 150 prov. I recently started the motor and it was running fine then when I let down to idle it will start running real rough and die, and the only way I can get it to start again is if I choke it?!?! I can get the motor to operating temperatures and the only way I can get the darn thing to start after it dies is by using the choke, if I turn the motor off by key it will fire without the choke. Is the problem in the carbs causing a lean condition maybe, any help would be much appreciated!

 

[JB]

Re: Yamaha 150 prov troubles

Ahoy, Snoopy.<br /><br />Sounds like you are dropping a few cylinders due to fuel starvation.<br /><br />Check the fuel tank vent and pickup for restriction, all fuel lines for restriction or air leak, and fuel pump for strong output.<br /><br />If all those check out, what happens if you squeeze your primer bulb?<br /><br />No change? Spray some premix fuel into each carb and see if it picks up. <br /><br />On fast idle, pull each plug wire and listen for rpm drop. While each wire is off, check for a hot, blue spark to the block. If rpm does not drop on a cylinder with good spark, overhaul that carb.<br /><br />Let us know what you find. Good luck.