The Stovebolt Site Forums The Shop Area Engine Shop Fuel Pumps and Other Nonsense

Alright, I want to tie some strings on that previous thread about a possible wiped fuel pump cam.

I figured it would be easier to start a new thread and give a recap.

1950 3100 was running fine with a newly rebuilt carburetor and a year old Carquest fuel pump. It ran fine and showed no indications of trouble for a couple hundred miles or so. It then conked out and couldn't be restarted.

Tests showed the carburetor wasn't getting any fuel. A brand new Carquest fuel pump was acquired and it too failed to pump any fuel to the carburetor. I assumed that the fuel pump cam had worn down to the point where it wouldn't operate the pumps.

After all, what are the odds that a brand new pump wouldn't pump a drop right out of the box?

Well, I installed the old original style pump and it at least pumped some gas but was too raggedy to be relied upon so I sent it to Then and Now Automotive for a rebuild.

Notice the photos of the cam and the failed pump. The cam is varnished up on one side and worn on the other. No look at the wear pattern on the pump arm.

The stupid thing was assembled incorrectly. The three pieces of steel that make up the arm were riveted together unevenly so that only one of the ~1/16" wide strips of metal made contact with the cam.

The failed one has the golden lid. The new one looks like a decent unit but wouldn't pump a drop.

The arms of these pumps don't move very much at all to work the diaphragm. I figure if it's off by a sixteenth of an inch or so it won't work the diaphragm enough to pump enough fuel or even pump any at all.

So, the rebuilt unit appears to be an original unit re-manufactured by Airtex a long time ago or possibly a "new" unit made by Airtex a long time ago. In any event, Then & Now did a great job on the rebuild. $52 for a rebuild kit and I do the work, or $63 more for them to do it. Seemed like a bargain to me. It's cleaned, straightened, new pins, valves, filter, and clear coated.

From this experience I'll advise anyone considering purchasing a new fuel pump, particularly a Carquest fuel pump, to forgo that choice and have the fuel pump you already own, rebuilt.