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Merc 1997 150 Hp efi throttle control problem

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Burtsy

New member
I have a 1997 Merc 150HP efi on a '97 Ranger Comanche 461vs. This motor has an intermittent throttle control issue which does not show up on diagnostic. When the throttle is full open, the RPMs will drop down suddenly below 2000 RPM then rev back up without moving the throttle control. This problem has come and gone for the last 2 years. Any suggestions???
 
Re: Merc 150Hp efi throttle control problem

Had the fuel pump checked and everything is fine. Good pressure, not dirty. We ended up changing the TPS with no change in the problem. The problem does not occur when running on a dyno, it only appears on the water. My next guess is stator??? or possibly a problem inside the fuel tank. What are your thoughts???
 
Re: Merc 150Hp efi throttle control problem

That points right back at the fuel pump or a fuel restriction.

Many motors will run fine under minimal load, but once you get some loading plus the backpressure from the exhaust they are no longer "getting enough to drink" to keep running - so they bog.

That is a very common scenario.

I would start all the way back at the tank (dirty or crud inside?), tank pick-up, anti-syphon valve (if equipped) - air getting into a fuel line fitting etc....
 
Re: Merc 150Hp efi throttle control problem

Thanks for your responses. I opened the gas tanks and discovered plastic shavings and other debris. I cleaned it out and the engine runs GREAT now.
 
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