NOW WHAT? 1977 Johnson 85hp

[Ryster77]

I have just put $500 into my motor (power pack) it ran great with lots of power for 1 day. Second day out it will run great full throttle for 5 seconds and then drops rpms. I can pull throttle back to 3/4 and in about 4-5 seconds the power returns then I go back to full throttle and same thing. I can cruise 1/2 to 3/4 throttle without a problem but soon as I go to full throttle same thing. Everything checked out good when they replaced power pack. Any help would be greatly appreciated.
Thanks

 

[Joe Reeves]

Re: NOW WHAT? 1977 Johnson 85hp

Have someone pump the fuel primer bulb while you're underway. If the problem ceases to exist, suspect either a fuel/air leak at some point between the fuel pump and the fuel supply or a failing fuel pump.

If on the other hand, the fuel primer bulb has a tendency to be drawn flat as you're underway, that would indicate a fuel restriction between the fuel primer bulb and the fuel supply..... usually a anti siphon valve which is located where the rubber fuel line attachs to the build in tank.

 

[jddenham]

Re: NOW WHAT? 1977 Johnson 85hp

Could be water or debris in your float bowl that is only blocking the main jet at full throttle.