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25 Hp idle problem

T

trapshooter

New member
"I have a 25hp 2003 merc that

"I have a 25hp 2003 merc that I am having idle problems with. Runs fine at higher rpm but might have some hesitation getting there. Seems that the bulb doesn't stay hard when running. Can't get it to continue idling with a load or in neutral for more that a few minutes without re-priming the carb. chocking doesn't seem to help. new plugs, gas, tank bulb. I have been testing in a 55 gal drum. Please help, Don"
 
"If you need to give the bulb

"If you need to give the bulb a few squeezes to fill the carb with fuel, then I would say a faulty fuel pump.


James"
 
"True, but keep this in mind:

"True, but keep this in mind: The fuel pump generates about 1 psi fuel pressure at idle, and about 4 psi at wide open rpms. Pump up the bulb and you can generate 10 psi easily, and that can craate a rich idle condition. You need to set the idle mixture with the fuel pump alone making the pressure.

Jeff"
 
"Merc update. Motor ran fine l

"Merc update. Motor ran fine last fall and I never changed carb adjustments. Cleaned filter that was bearly dirty. Was able to view gas bowl which stayed full all the time. Tried adjusting idle circuit which did little. Idle speed adjustment with choke knob does nothing. Bruke down yesterday and pulled carb to re-build.Expensive little merc re-build kits. Thanks for your suggestions, Don"
 
".."Expensive little merc

".."Expensive little merc re-build kits."

Ain't they! Literally just got through re-adjusting mine, and it ran great last year.

Jeff"
 
Yep expensive they are. Found

Yep expensive they are. Found green gunk in carb and a big piece on fuel pump causing a small hole in diaphragm. 2 bumps in rubber probably from alcohol. I don't think I will ever use stabil again. Just stick to seafoam every other tank. I actually bought a $50 kit from a local dealer instead of the $81 buck kit that was on the mercury site. Did'nt have all the screws and junk that you can save and reuse.
 
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