Yamaha V150 Power Loss

[bombdoc]

I recently purchsed a fish & ski with a 2004 V150 TLRC. Put the boat into the water and immediately had probrems keeping the motor running. The dealer found a bunch of water in the tank. Drained the tank and ran fuel stabilizer, and everything went well for 3-4 hours of run time.
One morning the motor lost some power, maxing out at about 4,000 RPM, but then got better. After stopping the motor 30 minutes, it refused to go above 2,500 RPM (except for an occasional bump to 2700-2800 for a second or two) for the next 3 hours of run time. It will rev up to 4,000 + with the engine in neutral.
The fuel filter is clean, with no water showing. Both fuel pumps were replaced within the last couple of weeks. Fuel line from the tank is unrestricted.

 

[rodbolt]

Re: Yamaha V150 Power Loss

most likly picked up more water.
or by now you may have smoked a piston as well.
that engine doesnt like running lean.
check compression first, check spark while your at it then go fix the fuel system.
do a forum search on home made spark testers.

 

[bombdoc]

Re: Yamaha V150 Power Loss

I ran the engine from a seperate fuel source with the same result.

 

[rodbolt]

Re: Yamaha V150 Power Loss

once you get water or that watery debris in the carbs no amount of filter changing or running on a seperate tank will help, all that will help is cleaning the carbs,fuel pumps and lines.
but first test spark and compression.
the amount of running you have done if its lean its very possible you smoked a piston
luckily that oiling system injects oil aft of the carb so there is some protection.
but at least we know its not in the hull systems its on the powerhead.

 

[bombdoc]

Re: Yamaha V150 Power Loss

I just wanted to give an update on the motor. I checked the plugs and found them fouled. They also turned out to be the wrong type. I put in factory plugs and took for a test run. I ran great. I took it out the next day for a family outing; after running fine for 5 minutes, the same symptoms appeared.
The Yamaha dealer's mechanic had told me before that the carbs looked fine, but I decided to look for myself. Sure enough all three carbs had junk in the bowls. After cleaning them out, it ran like a top. I installed a filter/water seperator to make sure this doesn't happen again.