Fuel Pump has no Suction/Pressure

[Rhadley]

I have a 1984 2.5L Mercruiser with an old-style mechanical fuel pump (bowl and filter on top of the pump) and no fuel is getting to the carb. I just replaced the filter inside the pump. If I disconnect the inlet fuel line to the pump, I feel no suction when the engine is cranked and my finger is on the pump inlet.

Do I somehow need to prime the pump? Is it possible to install the pump so that the arm is not properly positioned on the cam in the engine?

Thanks.

 

[Alpheus]

Re: Fuel Pump has no Suction/Pressure

You may need a new pump. If the diaphragm is torn it will not work no more...

 

[wire2]

Re: Fuel Pump has no Suction/Pressure

Did you have the pump assembly off the block to change the filter? If so, the push rod may have dropped into the bilge.

 

[Rhadley]

Re: Fuel Pump has no Suction/Pressure

Yes, I had it off earlier because I thought it might be bad, but it seemed to pump when I moved the arm manually. I don't think it has a separate push rod piece, but I don't see anything in the bilge. Thanks.

 

[Alpheus]

Re: Fuel Pump has no Suction/Pressure

Your engine does not have a separate push rod for the fuel pump.

Make sure that the fuel pump lobe is still good on your cam shaft. Set up a dial indicator or use a phenolic rod to put in there while turning over the engine and feel/watch for movement...

 

[wire2]

Re: Fuel Pump has no Suction/Pressure

Your engine does not have a separate push rod for the fuel pump.

Make sure that the fuel pump lobe is still good on your cam shaft. Set up a dial indicator or use a phenolic rod to put in there while turning over the engine and feel/watch for movement...

I thought about the location of the cam in an I-4 after I posted, realized it probably doesn't have/need a push rod.

IF you don't have access to a dial ind. or a non metallic rod to test with, you could loosen the bolts of the pump so that the pump is free to come away from the block, lightly push it against the block with your fingers. Crank the motor, see if the cam lobe pushes the pump away from the block.

 

[Rhadley]

Re: Fuel Pump has no Suction/Pressure

Installed a new pump and it now works. Old pump still had a good diaphram, but the valve was corroded and not letting the gas go out of the pump.