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80's Mercury 25hp Cuts Off w/o priming

M

mercury25obx

New member
I just picked up this engine and it turns right over. It seems to be idling high and will keep running if I prime the ball, but if I don't it will cut off. The carb has been recently cleaned, but it still having a hard time running on its own. I noticed a chip in the carb where I believe the fuel pump is at the top thread. I've attached a picture below. Any help would be appreciated.
Screenshot 2020-04-02 at 3.04.54 PM.jpg
 
Replace the fuel pump components, maybe you can also replace that cover. It could be idling high because the PO didn't know what they were doing and turned the idle adjustment screw to try to keep it running. The low speed needle adj. should be set with a warm engine in forward in the water at low rpms, [turn the needle in then out 1 1/4 turns for initial setting] then turn it slowly in and out until the engine runs smoothly.
 
I appreciate it, I’m the furthest thing away from a mechanic there is, but glad we are on the same page with it being a fuel pump issue. Now I have to find that part without paying for a brand new carb.

Quicksilver said:
Replace the fuel pump components, maybe you can also replace that cover. It could be idling high because the PO didn't know what they were doing and turned the idle adjustment screw to try to keep it running. The low speed needle adj. should be set with a warm engine in forward in the water at low rpms, [turn the needle in then out 1 1/4 turns for initial setting] then turn it slowly in and out until the engine runs smoothly.
Click to expand...
 
Fuel pump parts are usually just a diaphragm, check valve and gaskets, no need to replace the whole carb, use you serial Nr. to look for parts.
 
..."The carb has been recently cleaned,"

Ah, but did they install the carb to block gasket correctly? It as a little hole in it that has to line up or the fuel pump won't function.

Jeff
 
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