Bizzare problem under load

Rekon531

Recruit
Joined
Jul 26, 2010
Messages
2
Hi All - I'm new to the world of iBoats, so thanks for having me! I'm very well versed in the stern drive world, but new to the world of outboards - a buddy and I recently picked up an '85 Evinrude 120 as part of a project boat. The engine ran, but not well, so as part of my troubleshooting I discovered a blown piston. We tore down the engine, replaced the piston, put it all back together, and am back to my original problem, which is still showing itself. It will start just fine in the yard on flushers, and I can run it up to WOT unloaded with no problem. When I put it in the water though, it's questionable if it will even start, and if I can get it to run, I can't get it to do any better than idle under any sort of load, no matter how much I open the throttle. I have rebuilt all the carbs, verified electrically that everything is functioning with a spark tester on each cylinder, and verified even compression across all 4 cylinders. I'm stumped...I was thinking I might have a timing problem, but I'm not getting any premature ignition, so I'm not sure it's the root of the problem. Anybody seen this before, or have any idea where to go from here (besides the boat graveyard...) Thanks!

-Matt
 

jjacobs007

Lieutenant
Joined
Mar 10, 2009
Messages
1,257
Re: Bizzare problem under load

Hey welcome to iboats!man my johnson did the same thing but its a 70hp 1979 model.I rebuilt the carbs put new fuel pump and tested all ignition parts with ohm meter.Then ran it and was doing fine for a moment than slowed down again.Then i checked the sqeeze bulb and felt ok but i wa wrong had extra one replaced it and still runs good two years later.My point is could be one thing or combos.Hope this helps let me know when your haulin bass.
 
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