79' Johnson 85hp issue

[Ben Petree]

I just got an 1979 85 hp johnson runs great except for when i was out the other day it suddenly started to cut out like it was fouling out so i cut the engin and verified that the tank was venting properly and i even switched to my reserve tank in the back started it back up seemed to run great for about 1 minuted then did it again. got it home checked the spark on all plugs cleaned the carbs and adjusted thr fuel screws to one turn out run great with the muffs on seems to only have this issue in the water with a load on the motor not sur what to do next.

 

[tashasdaddy]

Re: 79' Johnson 85hp issue

time to trouble shoot on the water, when it does it again, is it running hot? check spark on all 4 cylinders, could be coil heating up and failing. what did the spark plugs look like?

 

[Ben Petree]

Re: 79' Johnson 85hp issue

i checked the spark on each cylinder it gets good spark the plugs were wet when i pulled them out so i adjusted the fuel screws in 1/4 turn each the problem seems to start when im running at low rpms which tells me that maybe the slow speed mix needs to run leaner. It does have a new coil on it.

 

[ezeke]

Re: 79' Johnson 85hp issue

What screws are you turning? The 1979 85HP carburetors have all fixed jets, there are no adjustment needles.

After you take a compression test, you should take take the cover off the carburetors and make sure that the carburetors' throttle plates are 100% synchronized with each other throughout the entire range of motion.