omc seadrive rpm problem

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Robert Pitts

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Jul 17, 2006
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I have an 89 16L. OMC sea drive on a 21' Wellcraft. I have been fighting this problem for two years now. The engine rpm drops from 4900 to 3000 rpm intermittently. The carbs have been rebuilt. Installed new coils, powerpacks and voltage regulator. I added an electric fuel pump to the system. The throttle cables have been replaced. I have even bypassed the pumps and filters and gone with an external six gallon tank but still have the problem. It is extremely intermittent. I can run it for 5 minutes or get ten miles offshore before it drops off. Any help will be appreciated.
 
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Robert Pitts

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Jul 17, 2006
Messages
11
Re: omc seadrive rpm problem

Robert said:
I have an 89 16L. OMC sea drive on a 21' Wellcraft. I have been fighting this problem for two years now. The engine rpm drops from 4900 to 3000 rpm intermittently. The carbs have been rebuilt. Installed new coils, powerpacks and voltage regulator. I added an electric fuel pump to the system. The throttle cables have been replaced. I have even bypassed the pumps and filters and gone with an external six gallon tank but still have the problem. It is extremely intermittent. I can run it for 5 minutes or get ten miles offshore before it drops off. Any help will be appreciated.
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Robert Pitts

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Jul 17, 2006
Messages
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Re: omc seadrive rpm problem

No, I have not been able to reproduce it out of water. I have also had it to a mechanic that ran it in a tank and could not reproduce it.
 
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markp0730

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Jun 6, 2006
Messages
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Re: omc seadrive rpm problem

Just a suggestion, Check the exhaust system. I had the same problem, low rpms at wot. Had carb rebuilt, tune ups, nothing worked. Ended up being the "flappers" in the exhaust system that are there to prevent water from getting into the engine had melted loose, fell down into the y section of my exhaust and created a restriction. depending on how the flappers would move around down there dictated how the boat would run.

Just a suggestion.
 
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Robert Pitts

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Jul 17, 2006
Messages
11
Re: omc seadrive rpm problem

I looked and don't see what you are referring to. This is an outboard engine.
 
bomar76

bomar76

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Re: omc seadrive rpm problem

And as such should be posted under the appropriate Outboard section of the forums....
 
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