71 Johnson 20hp seahorse that sputters when running with the motor cover on

[racerone]

Is it running in a barrel ??---------Do you have adequate ventilation ??

 

[xbilly97X]

I have a 1971 Johnson 20hp seahorse that sputters when running with the motor cover on. If i remove the motor cover it runs great! I had the powerhead gasket replaced last year along with a carb cleaning and new plugs. What may be causing my issue?

 

[nwcove]

you have an exhaust leak , have a good look at the ph gasket and the exhaust cover gasket.

 

[xbilly97X]

thank you for answering. I will try that

 

[nwcove]

cly and crankcase section at marineengine.....parts 23, 24 25 etc.i personally would focus on the base gasket tho.

 

[AlTn]

exhaust cover gaskets ..part no. 0316162 < 2 needed >....if you have to pull the powerhead...powerhead to exhaust adapter gasket is #0314421

 

[racerone]

?????--The way I read he has replaced the powerhead gasket already.

 

[nwcove]

?????--The way I read he has replaced the powerhead gasket already.

yes, but was the job done right? were the mating surfaces cleaned up, have the bolts loosened etc etc. just because the base gasket has been replaced at a shop does not mean its not leaking !! jmo

 

[xbilly97X]

thanks for all the input guys! I really feel you are leading me in the right direction. should I use a gasket mate when replacing these gaskets?

 

[AlTn]

thought of one other possibility...is the lower spark plug wire or boot arcing to the hood latch when the hood is on?....not likely,but wouldn't be the first time...if gasket mate = gasket sealer...yes, both sides of the three in question

 

[boobie]

Take the motor cover off and run some oil through the carb and see if you can see where it's smoking.