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1970 Johnson 85hp, seems to misfire after engine warms up

M

makak

New member
Hi All,

I have a 1970 Johnson 85hp motor. The engine starts up no problem, after about 30min of boating the engine seems to misfire when I put it on full throttle( pop pop noises) I reduced the throttle a bit and it runs fine.

When I stop the engine, it didn't want to start again. towed it home, started the next morning and it started(turns on and off no problem).

I get the feeling it has something to do when the engine warms up, like a cracked coil somewhere which expands with heat which probably grounds the current or something. when the engine cools down, it starts/stops fine and runs ok until it warms up again.

Engine is not overheating, i have installed a tail tail water is coming out normally the whole time.


Any ideas?


thanks!
 
Re: 1970 Johnson 85, seems to misfire after engine warms up

next time it does it, do a spark check and let us know.
after the spark check,( and you have spark on all cyl) pump up the fuel bulb, and see if that helps it start.
 
Re: 1970 Johnson 85, seems to misfire after engine warms up

coueytwo said:
next time it does it, do a spark check and let us know.
after the spark check,( and you have spark on all cyl) pump up the fuel bulb, and see if that helps it start.
Click to expand...


thanks, Ill try doing a spark test right after, I have tried pumping the bulb when it happens, the bulb is hard. I even opened the fuel filter to make sure theres fuel and there is.

The thing is I only have 1 motor, and when it happened 3 times so far (getting stuck with motor not starting) i was lucky enough to wave someone to tow me out! If i try leaving it in a water bin for 30min to warm up then engine would that be Ok? with ears on of course.
 
Re: 1970 Johnson 85, seems to misfire after engine warms up

sure the thing is to get it to do the same thing, so you can test it.
 
Remove the flywheel and set points at 0.010"-------Clean distributor cap and rotor.-----Check anti reversing spring.---------Replace the wee boots on the plug wires at the distributor cap.-------Note, If still original then plug wires are screwed into the distributor cap.
 
I have the same exact motor. I have not started it in few years. Has good compression. makak ... if you would like back up parts, I would be willing to part with the whole thing.
 
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