Motor won't accelerate

[duke 1935]

My son has a 1992 Yamaha 150 PorV6 cylinder motor. Motor starts and idles good. It will putter around at 22 to 2500 RPM but when you try to accelerate it drops back to around 1000 RPM or about 7 MPH. We drained the gas tank installed new (6) spark plugs and added new fuel. No change.

 

[mikesea]

Re: Motor won't accelerate

If it hasnt run for a while,it sounds like typical dirty carbs

 

[chicknwing]

Re: Motor won't accelerate

The idle circuit is the only clean circuit in the carb. spray carb cleaner into the intake when you are advancing the throttle, it the motor takes off, clean your carbs.

 

[duke 1935]

Re: Motor won't accelerate

Thank you both for your reply. The motor was running very good after it was in the shop for a tune up. It plained out at 60mph. Somehow water got in the tank and we drained the tank and flushed it and changed plugs but it has never regained it's power. I am wondering if B-12 would help?

 

[rodbolt]

Re: Motor won't accelerate

no snake oils, no sprays, do that and you may get to post about scuffed pistons,
remove and clean the carbs and flush the lines and go boating.
spraying carb cleaner down the carbs while running is strictly NOT reccomended as it tends to cut the lubrication.
water in the fuel is getting more and more common as is bad gas from sitting. todays fuels last about 3 months, even with a stabilizer, before it starts turning to varnish.

 

[duke 1935]

Re: Motor won't accelerate

Thanks Rodbolt,
We called the dealer and he told us of a local Yamme shop to go too. When I find out what the problem is I will post the fix so maybe it will help some one sometime if they have this problem.

 

[duke 1935]

Re: Motor won't accelerate

The good news is we found out what the problem is and the bad news is we need a new computer ($600.00). This is a common problem with this motor but will be as good as new with the change. Thank you all for your input.