older yamaha help

[fatfinger]

I have a '94(I think) yamaha pro 50.recently at any speed over about 4mph it starts chugging and shaking as if its real low on oil but oil is almost full or full.sometimes it run perfect and without warning starts the shakes and chuggs.did it once before and it wasn't getting enough fuel.but now it seems to be.should I try new fuel line?tank? Oil filter? Please help and thanks

[Rivernut]

I had a 25 Yamaha that did the exact same thing. Impeller had gone bad and it was overheating. Check for water coming out of pee hole. Good luck

[Ufatz]

Something wrong in fuel system. Check all connections, clean everything and check tank for water.

[Surface Tension]

Something wrong in fuel system. Check all connections, clean everything and check tank for water.

I'd suspect water. Pull the plugs and you might find water droplets on the spark plugs.

Pull the fuel filter and you might see some in there as well.

Next would be to jack up the trailer and let the gas settle. Get a siphon hose to the lowest point in the gas tank and siphon some gas into a clear container. Let that settle and look for water in the bottom and or swirls in the gas. If you see either start you'll at least have to get the water that is separated out of the tank by siphoning off the bottom or all of the gas out of the the tank.

[fatfinger]

Thanks guys.startin with the simplest things first.different tank and new hose.gonna check plugs first thing tomoro as well. And is it wise or unwise to use any kind of additive(isoheet, gumout, etc.)? And where would a guy find where to set the gap for new plugs? Again thanks.

[boatfixer]

Products like Stabil are fine to put in there. It will do more than Heet.

Plug gap should be .030-.035