yamaha 9.9 4-stroke revs up when slowing down

[ggreenbe]

I have my yamaha hooked up to cockpit controls in my sailboat.Over the weekend we had to motor an awful lot. When I came up to the mooring I slowed down, moved the throttle so that the speed and rpm were very slow and then it revved up by itself. I took off the kill switch so we would stop.I had been fiddling with the idle adjustment thinking it was idling too slow. But that wouldn't cause this problem,would it? Any ideas?
Second question, I have to pump the remote control lever several times in order to start the engine when it is cold. It will stay going only if the neutral throttle level is all the way up reving the engine high untilit warms up. Then except for the other annoynace the engine runs and sounds fine. Is this the sign of a problem? Thanks for any advice. Gerry

 

[garyN]

Re: yamaha 9.9 4-stroke revs up when slowing down

You have a bad fuel pump - likely has a hole, gets air, then get primed, then pumps the fuel and you speed up and down. mine only went up and down about 1000rpm.

Get out your wallet - but you can find a replacement diaphram - but Yamaha did redesign the pump and made it water cooled - so see if yours has a water line -

If you need a new pump, get ready to pay (I think) about $200.00. May be a warranty coverage, if you have it.

 

[ggreenbe]

Re: yamaha 9.9 4-stroke revs up when slowing down

Gary, Thanks for the response.Another post suggested pumping on the bulb when it seems like it is stalling. This would be a test if the fuel pump is faulty. Trying to keep things simple,could it just be the bulb in the fuel line and a low-set idle? Gerry