1985 johnson 90 hp motor run awesome - changed new starter now wont start

[benmascoe]

1985 Johnson 90 hp - motor ran well until changed brand new starter. Spins over fine but seems to want to start but wont fire up. Gave spark advance little nudge forward and she fired up but seemed to be running on 2 cylinders or very low idle. Let it run like that for awhile to get her warm but then conked out and now doing same thing of wanting to start but wont. Gas feed seems OK - primer bulb remains hard when pumped up. Need help.

 

[Bosunsmate]

Re: 1985 johnson 90 hp motor run awesome - changed new starter now wont start

What happened to your old starter to make you get a new one?
Have you checked spark with a spark tester?
I like the 90hp motors, good size, not too thirsty

 

[benmascoe]

Re: 1985 johnson 90 hp motor run awesome - changed new starter now wont start

What happened to your old starter to make you get a new one?
Have you checked spark with a spark tester?
I like the 90hp motors, good size, not too thirsty

Old starter was burnt out. Spark ok with spark tester, fuel circuit also good with primer bulb staying hard once pumped up. The only other thing apart from starting by nudging the advance spark was the friction throttle knob was loosened by mistake but has been tightened up - seemed to make a difference with motor conking over for a little longer before sputtering out.

 

[benmascoe]

Re: 1985 johnson 90 hp motor run awesome - changed new starter now wont start

good to see you from NZ - awesome forum.

 

[Bosunsmate]

Re: 1985 johnson 90 hp motor run awesome - changed new starter now wont start

Have you looked at the spark plugs? I was working on one of these, the bottom spark plugs were wet so i thought they were flooding, i tried to light it later with a flame and it was water. Head gasket was leaking slightly on both sides which i hadnt picked up with compression test..
so check for that and also check the colour of the plugs, do the two on the top look similar to the bottom two?
if that doesnt show anything. Pull the safety line off on the control so you wont get spark and then turn the motor over a few times, check all sparks a wet with fuel, if not then a carb/s could have a blockage.
If that doesnt work check timing. Advancing that spark is probably just putting more work on the cyliders that a working rather than getting all four working properly.

Yes NZs a good place to be now-we a anti winterising here unlike the northern hemisphere people

 

[keefallan]

Re: 1985 johnson 90 hp motor run awesome - changed new starter now wont start

It never hurts to do a compression check. That way you'll know what kind of pressure is in the cylinders in relation to each other. It's just something to rule out and just plain good peace of mind. You're looking for 115-120 I believe for your motor.

 

[emdsapmgr]

Re: 1985 johnson 90 hp motor run awesome - changed new starter now wont start

That engine has to crank at least 200-250 rpm's in order for the ignition system to develop enough voltage to fire the plugs. Make sure the battery is well charged.