I have a 07 yamaha 150 2stroke. I put it in the water last week and it wouldnt go over half throttle unless you were really slow with it. Once it did get to full throttle you could hear that it just didnt sound rite. Since then i have changed all the spark plugs cleaned the carbs changed the fuel filter in the hull and the little one on the side of the motor and put fresh gas in it. I figured all would be good to go out fishing this morning. Well all is still not good. When we pull out of shem creek i went to put the throttle down and now all it will do is half throttle, once at half throttle it just dies and will not pick back up until it gets back down to half throttle. I have run out of options besides pulling the carbs back off and cleaning again. Is there something else that im missing?
Maybe a rev limiter is happening or you have lost a cylinder. I would check spark on each plug first then probably a compression check. Also have someone pump the bulb when it is falling off and see if it picks up, if it does then you know it is a fuel flow issue.
Rick
Sounds like a fuel delivery problem.
Maybe check your air intake?? Happened to me…
I talked with a good friend last night about my issue and he said that just because i cleaned the carbs i mite not have gotn everything out and he is saying that i need to buy a rebuild kit for them and then have them resinken.
MMSI# 338048053
Ditton on ECU1984.
I had this same problem on a Yamaha 25.
I pulled the carbs 4 times trying to clean…did not use a “kit”. New fuel filter, dumped gas tank and started fresh, new hose and primer bulb, etc.
Couldn’t get it right.
Took it to my mechanic. $200 later it was fine. He cleaned the carbs and put in the carb kit.
Although I was as “thorough” as I knew how to be he said he has a machine that soaks them and gets every nook and cranny.
have you done a compression test and checked for spark on all cylinders?
start att eh begining, and work from there, its easier.
I’m now at www.teamcharlestonmarine.com
I went yesterday and just backed the boat into the water over at the ncfc and found out that when it starts to act up if i hit the choke it will pick the rpm’s up for a sec. so im lead to believe that it is still fuel related.
MMSI# 338048053