1988 Johnson 150GT bogs down

[dgoock]

I just bought a boat with a 1988 Johnson 150 GT. Runs great for about 5 minutes then it cuts back and mises badly. Pull back on the throttle and it idles fine. Give it throttle and it will not go and sounds bad. Leave it with throttle and it will surge a little after a few minutes. back off the throttle and it is ok and giving it a little throttle it runs good till it gets too much throttle then it bogs down and pits and misses. Please, any suggestions before I tear in to it. I have ordered 3 carb rebuild kits for the 3 2-barrel carbs.

 

[oldcatamount]

Re: 1988 Johnson 150GT bogs down

sounds like you are on the right track with the carb kits. Usually a surging motor is a sign of fuel restriction.

 

[mak747]

Re: 1988 Johnson 150GT bogs down

Might also check for a fuel restriction, air leak in fuel lines/filters or possibly bad fuel pump. Have someone pump the bulb while you are giving it throttle and see if it starts running. I had the same symptoms with my 1986 GT150 and it turned out to be a bad fuel pump.