OMC Dies after acceleration PLEASE HELP

[Phantomrider09]

I have a 1988 OMC 5.0, it will idle perfect, in neutral I can run it all day at all RPM ranges, I go into forward, full throttle for about 30 seconds and it dies. I let it sit for about 2 min. and it will restart and then do the same thing. I was a boat mechanic for 8 years, and I cant figure it out to save my life. Can you guys please throw ideas out there.......anything im so lost and to the point where im going to drop a new engine in it. Thanks in advanced.

Rob

 

[KaGee]

Re: OMC Dies after acceleration PLEASE HELP

I think a troubleshoot of the shift assist setup may be a starting point. A bad switch, out of alignment switch or possible defective ESA module?

 

[Phantomrider09]

Re: OMC Dies after acceleration PLEASE HELP

Why would the shift assist make it happen?? It runs like a champ then just dies after 30 seconds of full throttle running. I can leave it at idle in gear and its fine.....Im going to check it tomm, but any other ideas out there?? Willing to pay for an anwser.......lol

 

[HT32BSX115]

Re: OMC Dies after acceleration PLEASE HELP

Try replacing your fuel filter. You also may have a plugged fuel pickup screen or a carb float level problem.

Why would the shift assist make it happen?? It runs like a champ then just dies after 30 seconds of full throttle running. I can leave it at idle in gear and its fine.....Im going to check it tomm, but any other ideas out there?? Willing to pay for an anwser.......lol

 

[Boatist]

Re: OMC Dies after acceleration PLEASE HELP

I also would suspect a fuel supply problem. Fuel pump check the pressure at high speed. Check or replace the fuel filters. Check the fuel pick up screen in the tank. Run a short time with the fuel cap off and if it runs good then check for a plug in the fuel vent.

 

[marunr]

Re: OMC Dies after acceleration PLEASE HELP

I agree with KaGee on checking your switches. When you put in gear the roller should center itself in the middle "V". I would suspect that as you accelerate it's riding up towards the top of the V and killing the motor. I had this problem a couple of years ago. If that's it, you'll need to verify that the switches are working (I suspect they are). That would point to an out of adjustment lower shift cable...or even a bad one that needs replaced. When they are stiff it will cause the switch to move on the V.

 

[dmarkvid2]

Re: OMC Dies after acceleration PLEASE HELP

I kind of had that problem too, although the engine never died, (460 King Cobra) I did loose RPMs, and it would bog down. My machanic told me it was because the Ethynol they use in the fuel deterierates rubber parts in the carb, and glogs the fuel from getting into the carb. I had to have it rebuilt.

 

[RubberFrog]

Re: OMC Dies after acceleration PLEASE HELP

Switch.
Definately not another ethanol ghost.

 

[Boatin Bob]

Re: OMC Dies after acceleration PLEASE HELP

I don't really think it's the ESA switches, even if the interupt switch was riding up high enough to activate the overstroke switch prevents it from doing that while in gear so unless it's bad or out of adjustment as well? And if he had the newer style ESA it should time out after 5 secs or so. Easiest thing to do here would be to unplug the ESA and go for a water test.

 

[marunr]

Re: OMC Dies after acceleration PLEASE HELP

I don't really think it's the ESA switches, even if the interupt switch was riding up high enough to activate the overstroke switch prevents it from doing that while in gear so unless it's bad or out of adjustment as well? And if he had the newer style ESA it should time out after 5 secs or so. Easiest thing to do here would be to unplug the ESA and go for a water test.

Right. It's easy enough to test, but running it with the overstroke switched depressed isn't consistent. When mine was doing that it would constantly cut out because the button on the overstroke switch will pop in and out if it isn't properly adjusted.

 

[RubberFrog]

Re: OMC Dies after acceleration PLEASE HELP

It was the same for me on my first/last OMC.

 

[Phantomrider09]

Re: OMC Dies after acceleration PLEASE HELP

Ok, I tested the switchs (as per the book), I rebuilt the carb, and changed the fuel filter (On engine and inside carb). Next option.......lol Match in the gas tank?? Pull the drain plug?? Im so frustrated....The boat rund like a champ at idle, in nuetral at all rpm ranges, but not while in gear over 1k rpms!!!!! PLEASE HELP here in NJ the season is short enough

 

[bruceb58]

Re: OMC Dies after acceleration PLEASE HELP

Try running with the fuel cap off to verify that it is not a tank venting problem.

Try running the engine off of a portable tank.

Have you tested the fuel pump?

When the engine dies, operate the throttle a whole bunch of times to see if the float chamber has run dry. You will see a few squirts of fuel for sure because the accel pump section will still contain some fuel but after that it has to get fuel from the float bowl.

 

[WZNYROBO1]

Re: OMC Dies after acceleration PLEASE HELP

Rob

I Have A 1987 Omc 4.3 And Have The Same Problem... I Idle, Run Full Out For About 8 - 12 Minutes And Then Its As If Someone Is Pulling The Throtle Back. It Does Not Stall, Just Runs With Little Power... Then After Shut Off For About 2 - 3 Minutes, Everything Is Fine. Or If I Leave It Running In That Condition It Kinda Clears Itself. I Have Put It In Nuetral During The Problem Time And I Get Full Rev Out Of The Motor. I Blew All The Lines Clear And Checked The Stone In The Carb.. All Were Clean. I Have Had Compression Issues With The Boat Before. Did You Do A Compression Check? I Want To Know More About The Shift Issue And /or Shift Interupter... Maybe We Can Help Eachother Here, Or Someone Can Get Us To The Problem

 

[1976 Slickcraft]

Re: OMC Dies after acceleration PLEASE HELP

Have you tried running on a portable fuel tank?
Could be a bad anti siphon valve.
Jesse