1976 johnson 70hp

[pate27]

i just bought this boat knowing the motor needed some work.it had been sitting for 2 years it ran very poor.so i checked the compression and all the cylinders were on 140psi,the ignition was puting out a strong blue spark on all the coils so i went straight to work on the carbs which were gumed up pretty bad.i soaked em and rebuilt them making sure floats levels were set right,new fuel line all through and of course new plugs gaped at 0.35 ,drained all old gas and fresh 50:1 fuel mixture.runs alot better now but is hard to get warmed up and soaks all three plugs and is hard to start after running awhile and shut off also smokes a little.any suggestions?also could the thermostat be causing this problem?i havent check it.not sure how to get to it.iv got a manual on the way.

 

[OBJ]

Re: 1976 johnson 70hp

Welcome Pate!<br /><br />What you need to do is check the engine to see if it's coming up on temp. Easy to do. Let it idle for a while and touch that flat place on top of the block just in front of the head. You should be able to leave your fingers there for several seconds before having to remove them. If it's cool to the touch, most likely the t-stat is stuck open and keeping the block cool.<br /><br />The t-stat sets at the top of the head behind a cover. Bout 5 bolts holding the cover on. There's a spring in there so becareful when you remove the cover.<br /><br />I would also consider changing out the water pump impeller also if you have no idea when it was last changed out.

 

[pate27]

Re: 1976 johnson 70hp

thank you for the help,the thermostat housing doesnt get very warm at all.im going to put a new one in it in a couple days and try it again.