120 mercruiser fuel pump

[fordworker]

Hello all, have a 1985 120 mercruiser. replaced fuel pump last fall with genuine carter replacement from dealer. (engine was cutting out and missing at high speed) replaced fuel line to carb (had small leak around threads after changing filter), never tried it in water and last week when I got it out it would not start. checked fuel flow and found none coming from pump. small vacuum pump easily pulls fuel through line, and pump works great if I manually stroke the push arm. thought maybe wrong pump, but dealer says it is right. suggested cam lobe may be worn. visual inspection shows that it looks ok. no gouges, or visible wear, very smooth. any other ideas?

 

[Bt Doctur]

Re: 120 mercruiser fuel pump

try matching it up to the old pump to check arm lenght.did you replace the plastic line from the pump to the carb or plug it off. plugged off will not let the diaphram operate correctly.

 

[whywhyzed]

Re: 120 mercruiser fuel pump

Stick a line from one of those pumps to a gas can, and just pump the lever by hand - if the pumps good, it'll shoot fuel about 2 feet.