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Mercury 50hp 4 stroke idles up on its own

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forkman

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[FONT=Roboto, arial, sans-serif] I have a 1999 Merc 50hp 4S that idles up on its own, no input from throttle.
The unit starts great @ about 1500 rpm, within 5 - 10 seconds the idle will
increase to & hold @ 3500 rpm without touching the throttle. The linkage
seems to be returning fully to the stops & not binding. Once the motor is
in gear the idle is fine & it runs great with plenty of power, as soon as the
motor is put back in neutral, it climbs right back to 3500 rpm.

Any thoughts on this?

1999 Mercury 50hp 4 stroke
Model: 50ELPT 4S
Serial: 0G799830

Thanks,
forkman[/FONT]
 
I have the exact same issue on the exact same motor.. I have yet to find a solution. I will be removing the carburtors tomorrow for inspection.
 
Check the floor mat........but seriously I suspect the source of trouble is the accelerator pump.
 
On rare occasion fuel pump. Do a carb kit, get a needle valve maybe too. Avoid alcohol "infected" fuel.
 
timguy said:
Check the floor mat........but seriously I suspect the source of trouble is the accelerator pump.
Click to expand...

Thanks for the tip! What is the issue with the accelerator pump? Does it cause an air leak and make it lean? ( I don't see a fuel line going to it)
The motor will also rev to high in gear.. the lowest I can get it is 1100... so trolling for walleye is impossible!
 
FIXED!! Disassemble the accelerator pump and cleaned all parts.. No damage to any of the diaphrams.. water tested and motor idles normal. Runs all the way up to 5800rpm with no issues.
 
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