OMC 4.3 losing power at WOT.

davesissom

Cadet
Joined
May 26, 2013
Messages
14
Hello
So here is my problem and if anyone can help it would be greatly appreciated. My 18 1/2 ft boat with 4.3 OMC loses power at WOT sometimes.... It idles good and mid speed is good. At wot it will run good @ 4200 rpms then suddenly drop to 3000 rpms for a while the back up. New fuel filter, points, plugs, distibutor cap, rotory button. Complete lower unit rebuild last year. It is worse with more weight in the boat and used to plane and run fine with a full load. I am running out of money and don't really want to throw parts at it. I have read about air bubbles in the fuel line and most of those problems have been solved with a new fuel pump and/or gasket. Should I try this or is it a carb issue. I'm not thinking it's electrical. It seems as though something is blocking the fuel. Maybe @ WOT it's sucking harder and therefor getting air????
Thanks, Dave
 
Last edited:

Levinz11

Senior Chief Petty Officer
Joined
Apr 1, 2012
Messages
726
Re: OMC 4.3 losing power at WOT.

Sounds like its running out of gas. Check the fuel system from tank to carb. Tank pick up tube, anti-syphon valve, filter, small filter in carb itself.

Good luck.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: OMC 4.3 losing power at WOT.

Sounds like its running out of gas. Check the fuel system from tank to carb. Tank pick up tube, anti-syphon valve, filter, small filter in carb itself.

Good luck.
Dittos! And check the fuel tank vent+ associated hoses. If it's plugged or partially plugged it can cause the same type of behavior.
 
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