Fuel Pump

[cudabob496]

The output pressure of my mechanical fuel pump
seems to be decreasing slightly. It is about 10 years old.
Should I replace the whole pump, or just replace the rubber diaphragm?

[AussieMark]

Pull it apart and see what's going on and take it from there.

[cudabob496]

Pull it apart and see what's going on and take it from there.

I checked Summit, and they have replacement diaphragms for only a few models of
mechanical fuel pump. But I agree, take it off, check model number, and go from there.
I noticed a decent big block fuel pump is about $120. Thing I'm wondering about, is will a new
$35 diaphragm get me another 10 years, or is there something else that goes bad about this time?
What have others experienced?

[Strawdawg]

usually, mechanical fuel pump diaphragms are good for at least 50,000 miles (at least in the old days) and then they start to show signs of fatigue which leads to cracks and the failure to pump.

There are also a couple of springs under the diaphragm and I suspect output pressure depends upon the condition of the big spring.

I would not be surprised to find that ethanol in the gas will shorten the life of the diaphragm as well these days

[HP_Cuda]

You can always go electric!!!