Motorheads----- help!

[Redfin]

Help! Please.....

I have a 2004 Yamaha 150 Four Stroke, and have had not one issue with it in 3 years. Had my first yesterday heading out to fish.

What it did: We ran it wide open for about 10 minutes heading out, then it hit: it would skip/lag, and drop power, almost like it was not getting fuel. RPMs were up-down-up-down-up-down...

I tried it at half throttle. As long as I ran at half throttle, no problems, ran fine. Soon as you pushed it a little past half, the skipping out came back.

So I was thinking it wasn't water in the fuel or bad gas (corner store keaton ), but figured motor related since mid to low RPMs would run fine... any thoughts?

I know its hard to diagnose a problem, especially on a forum post but thought I'd try here first (or second, put on HullTruth too) .

Thanks in advance!

[Chill-N-Grill]

Just had the same problem on my Yamaha 115 4 stroke. Turned out to be the thermostat was not letting the motor heat up. Cause carbon build up. Took it to Mike's Marine and he fixed it for a reasonable price.

[onefishtwofish]

I had the exact problem and it was debris in the fuel lines. When you go half throttle you are not pulling as much, as soon as I throttled up, it would cut off. Check filters and water separator.

[slayer]

Is that one of the motors that has a VST????? been hearing alot over at the hulltruth.com about clogged VST filters on the Yammies

[fishinfool]

The service manager where i just got my new motor from was telling me that the Yamaha 4 strokes are having huge problems with Ethanol. He said they recommended using Star Tron fuel treatment to reduce the ill effects of Ethanol or E10 fuels. This does not mean Ethanol will not attack your fuel lines. He also said that Yamaha fuel lines had fewer problems than Mercury or some others. They only use Yamaha fuel lines on ALL the outboards and PWCs they sell and service. He recommended too that the fuel lines be replaced every year as the rubber starts to deteriorate and the gunk from them winds up in your carbs and filters.

[Joe]

Try changing out the separator. It got me by for a while. Did have to take it to parkway marine for a full going through. Vst, pump diaphragms etc. My 150 hpdi was 10 yrs old and needed it. Great service!