2003 Yamaha 150 2 Stroke will not run at low RPM's

[jeffg777]

I have a Yamaha 150 that up until this weekend ran great. Now it will not idle and it will only crank at half throttle. I've replaced the spark plugs, fuel water seperator and cleaned the carbs. Still doing the same thing. I've noticed that there is a lot of oil coming out of the exhaust once I actually get it cranked and I'm not sure why. Any suggestions? I've been told it could be anything from the fuel pump to bad coils. Any help would be greatly appreciated! I have two little boys that want to go fishing!

[Sequoiha]

thats the exact same engine that I have, sounds like some basic diagnostics are in order, when you say clean the carbs, explain and did you link and sync afterwords.

[jeffg777]

I completely disassembled all three carbs, soaked them then cleaned all the jets, reassembled. I assembled them, just like they came off. I'm not sure how to sync the carbs though.

[rodbolt17]

carefully test the fuel pumps as well.
get ign coils out of your head.

[jeffg777]

Maybe a stupid question.....How do I check the fuel pumps?

[rodbolt17]

there is both a pressure and vacuum test in the service manual.
if you don't have a manual your sunk anyway.

this aint rocket science.

[jeffg777]

Ok, got it running. Apparently there was still trash in the jets. Now, the middle carburetor is pouring gas. I assumed it was the floats sticking but they appear fine. Any other suggestions?

[99yam40]

my guess is you are having trash getting into the carbs from line/pump after cleaning if you are cleaning properly.
something holding needle open, maybe trash.
try taking apart and clean again, flush lines well before putting carbs back on.

Pick up a Yamaha service manual for you motor and follow procedures in it for link and sync and adjusting everything

[jeffg777]

Ok, thanks. Nobody in town will sell a service manual for my motor so I downloaded one. I didn't see anything in it about syncing the carbs but I'll check again.

[Yamaha3535]

I recently bought a repair manual,its on a cd and seems not to have all the info you guys have. Which ones do you have and where do you get these from? I'm pretty sure mine is a service repair manual for my make,model and year but doesn't go into the details like sync the carbs.

[rodbolt17]

any Yamaha dealer will sell you the correct manual.
Yamaha also has a consumer hotline you can call.

if you clean the carbs and don't clean the fuel lines and replace the pumps you will get to clean the carbs again.