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1988 Johnson 140hp Misfire when accelerating

M

Martin1988Johnson

New member
I have a Johnson Outboard 140hp that ran great all that season. I've run though a few checks to try to diagnose the problem but my limited outboard knowledge is not helping the situation.

Compression test looked good - All (4) right around 120
Plugs need to be replaced - they look a little oily when I let it idle in the driveway
Ignition coils are new
Fuel pump is new

You'll see in the video, it runs hard while idling and then once I put it in neutral and push it a little the engine sputters/bangs at the higher RPMs

Any help would be more than welcomed!

 
PhilSch said:
Looks like ignition is crapping out on one or two cylinders.
Click to expand...

Phil - I replaced the ignition coils, definitely will grab new spark plugs next. Any other tips on where I could look to troubleshoot?

I read somewhere to swap out the spark plugs to a QL78YC to run a little hotter - not sure if that's the right path.
 
Check the flywheel key.----Put a timing light on each lead and see if ignition is the issue.----Did this issue show up suddenly ?---How did it run for you last year ?---Mark flywheel for TDC for each cylinder and see where each cylinder fires.
 
racerone said:
Check the flywheel key.----Put a timing light on each lead and see if ignition is the issue.----Did this issue show up suddenly ?---How did it run for you last year ?---Mark flywheel for TDC for each cylinder and see where each cylinder fires.
Click to expand...

I haven't checked that yet so I definitely will!
The engine ran great last summer and this happened once while we were driving on the lake and then didn't happen again the remainder of that day. It now happens each time when the engine is rev'd up.
 
I suppose I could say ---" you need a new powerpack "----If that does not fix it then try a stator.----But my posts urge folks to try / learn to trouble shoot first.----Up to you to do some looking.----See if perhaps throttle plates are opening too early.----Are you using a factory manual at all ?
 
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