1974 85 hs. Johnson start and run then die

E

ELS

Recruit
Joined
Jun 30, 2008
Messages
2
been running fine, started on trailer just fine, unload start across lake running rough die, checked vent,fuel filter bulbetc...let sit for awhile start back -up, had someone pump bulb , still died after a few minutes, again would not immediately start back-up ,,but could wait a little bit and it would run,,have to idle up and shift to get headed back to shore run a minute die again,,,,any suggestions??
thanks
ELS
 
E

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: 1974 85 hs. Johnson start and run then die

You will need to do a compression test and spark test to determine where the weakness is.

You are very likely running on three cylinders which does not show up until you run with a load on the motor.

If you have good compression and good spark with all of the spark plugs removed, then you should look at your carburetors.

Check the compression first; use a screw-in tester with a short insert.
 
E

ELS

Recruit
Joined
Jun 30, 2008
Messages
2
Re: 1974 85 hs. Johnson start and run then die

compression and spark are good, coils have crack in them could this be a problem???
 
iwombat

iwombat

Captain
Joined
Jul 12, 2006
Messages
3,767
Re: 1974 85 hs. Johnson start and run then die

It's certainly A problem. Whether it's THE problem or not is still up for grabs. It's something you'll need to fix regardless.
 
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