Mechanical Fuel Pump

[Joel Benatar]

Hi all
My electric fuel pump has become of constant use. The car will idle with the electric off however any hard acceleration and the engine starves and dies until I switch the electric on. I am now riding around with the electric on all the time and the car runs great. I then ordered in a fuel pump kit and had mine rebuilt. I am still having the same problems. Any suggestions.
Thanks

[Rudy van Daalen Wetters]

Joel,

How is your fuel filter? There could be some obstruction in the filter or fuel line that the electric pump can just barely overcome.

Rudy van Daalen Wetters
1963 GTE s/n 4001

[Jim]

I believe the stroke of the mechanical fuel pump can be adjusted. That is, the pump may not move much fuel because it's mechanism isn't moving enough. I had a similar problem and my mechanic did a "quick" adjustment (though, I wasn't there to see what was done).
Jim

[John Vardanian]

Joel,

When the problem arises (with the electric pump off) look at the glass filter bowl to see if there is an air bubble in it. There shouldn't be any. If there is air bubble, that would mean that the throughput of the pump is inadequate. The stroke of the the pump may be too short.

john

[oldfart3]

My Lusso had the same problem when I bought it. It wouldn't run AT ALL with the electric pump turned off.

It's really simple to remove the mechanical fuel pump - just 2 nuts, 14 mm as I recollect. There's a linkage that transmits the motion of the pushrod from the motor to the diaphragm that consists of 2 links and 2 pins, which can wear. One of the pins was fractured in my car, so I was getting NO pumping at all. I had a local machinist turn a few extra pins from stainless steel, which solved my problem.

The stroke of the pump is adjusted by the thickness of the base gasket for the fuel pump assembly, which also isolates the pump from some of the heat of the motor. If the gasket is too thick, the pump will not deliver a full stroke, too thin will overstress the linkage.

The rubber an fabric diaphragm can also deteriorate with age. I think Goeff at PartSourse in Maine is a possible source of replacement parts.

John Tarr