I replaced my mechanical fuel pump with 2 different units that were replacements for my unit and neither work. I have fuel to the pump but I have no output. The cam looks good and it won't pump by manually moving the lever either. Is there a way to test the unit? I don't want to order yet another unit from another supplier. Should I be able to blow through it? Seems wrong to convert to an electrical fuel pump to overcome this issue.

If you move the lever manually toward the pump body you should get vacuum at the inlet port every time you move the lever. You don't need a gauge just put your finger over the inlet port and pump the lever.

Tiny’s check is a good one to make. When I do that I put a deep well socket on the pump lever with an extension so I can smoothly move the lever to full stroke.

The diaphragm does not move very much with each stroke. It takes multiple strokes to create the vacuum on the inlet and build the pressure on the outlet. I clamp one of the pump mounting flanges in a vise so it is easy to move the lever without trying to hold the pump by hand.

While not something you like to hear it would not completely surprise me if you got 2 bad pumps. Based on what I read in some other forums there are a lot of bad mechanical fuel pumps being made overseas these days.

Make sure that you are getting the pump arm positioned correctly when you install the pump. While not easy to do you can possibly get the arm in such a position that the cam lobe does not push it.

One other possibility is that the cam lobe is so worn that it does not move the pump arm adequately.

My old pump from Napa replaced the glass bowl model about 30 years ago. Recently the truck started to stall and eventually wouldn't pump at all. The diagram was deformed so I ordered a replacement from Carter. It didn't pump in the truck or manually so I returned it after several emails and ordered a unit from Napa. This unit acted the same way and most likely can't be returned because it has been used. I inspected the complete cam by turning the engine with the crank and found the lobe to be about 1/2" and without much wear. The pumps lever matches closely to the old pump so I think it is being moved by the cam yet it will not pump gas or create pressure that I could measure. Manually moving the pump lever doesn't pump gas either even though gravity has provided gas into the pump. I can supply the part numbers for the 2 pumps that I have tried but if they are defective I guess that won't help much. They both were stated to work with this engine. I just have a hard time believing them both to be defective but I also believe that I have checked everything that can be checked. I am stumped!

I'm pleased with the pump I got from The Filling Station for my 53.

Napa mechanical fuel pumps for our cars are presently sourced from Carter. Sounds like both were duds. I would try one from Airtex (via Rockauto.com).

The Airtex pumps don't line up with the fuel lines and the base is much thicker requiring longer bolts. Don't ask me how I know that. After buying and returning several from different sources I found the pump from The Filling Station fit up with no needed modification. That was on a 53 235.

I tried two other Airtex pumps on my truck, the ones with the vacuum pump and they both leaked gas and oil. So they were producing junk. Fnixon1

Well scratch my idea then about using an Airtex pump.

Best to find an old AC pump and find a rebuild kit for it, I suppose.

Filling Station appears to be out of stock on the regular pumps. They do have a 37-51 pump with glass bowl in stock though.

When I put a pump on my 54 235, it was also from the Filling Station. Still working well 10 years later.

I had a similar problem with the fuel pump on my 216 in my ”˜50 Fleetline. I thought the pump was defective when I installed it. I decided to prime it by funneling gas down the line after disconnecting it from the filter. I poured a fair amount of gas back through the pump and reconnected the line and started the car. It is still functioning. I think I probably could have done that with the prior pump that I thought was bad. Go figure. I would not have thought it necessary to do, but it worked.

The pump I got from The Filling Station was the AcDelco 429 if I remember right. The fuel lines were about a half inch off of perfect but close enough to be able to get them attached without modification.

Napa has issued me a RMA and will credit my purchase. I then ordered another one from Napa that will ship to the store so I can test if it has vacuum when pumped. I am also looking for a fuel filter that I can insert before the pump without cutting the fuel line. I will provide an update later in the week.

I am almost certain that the reason these pumps don't work when mounted to the engine is that the arm which is actuated by the cam is not manufactured to the correct design. Upon closer inspection the arm of the replacement pump is of similar size and shape but it points too far up and not enough into the engine cavity to hit the cam and be pushed far enough into the pump to cause the diagram to pump. I friend is shipping me an origonal glass bowl fuel pump and when I get it I will provide another update. I did find a perfect fit with the screw in fuel filter that I purchased from Napa. I may have to bend the fuel and vacumn lines a bit though. It is from an Escort they tell me and it uses the same 5/16" line. Napa Gold Filter 3081.

Tiny, I think you are correct about the AcDelco 429. I did find a small tag on my old fuel pump that was stamped 429. If I need to I will search for that unit. So much for trusting when the vendor states a "direct fit". Thanks

I would check to see if line from gas tank was stop up or damage. also the pick up tube in the tank is connected. also line can have a small pin hole in it . I have seen some gasket too thick where it mount to engine cause the arm not get full contact with cam .

Well I installed a used glass bowl fuel pump my friend removed from a 216 CU engine. The size and direction of the pump arm matches what was removed. It seemed to fit and will pump fuel to a jar but the engine won't run without stalling. I measured the fuel pump pressure and instead of 3-4 lbs it was 0. I assumed that the pump is worn out NOT that the cam is worn or anything else. So I ordered an Airtex 429 thinking that it was the same as an AC Delco 429 but it's lever goes upwards instead of into the engine to touch the cam. The Airtex looks just like the Carter pumps that I ordered. Now I am back to searching for a pump and supplier that will work.

Have you tried The Filling Station?

You could also buy a rebuild kit from The Filling Station or Then and Now Automotive. Not a tough job and Then and Now has some step by step instructions on their site.

https://www.then-now-auto.com/

Dave

Check the pump body to see if it warped where the glass bowl fits. It is common for the die-cast (pot metal) to warp over time from the pressure of the parts that hold the bowl in place. If so tapering a cork gasket to get a 360 deg. seal might solve your problem.

I found a flow problem from the tank into the fuel pump. Not sure if it was low flow for a while or just developed the last time I tried the fuel pump due to the tank being almost empty. I blew backwards into the tank and the flow is good now. I will blow the tank out now. I will replace the fuel petcock while the tank is empty. Then I will try the pump that is installed now. I used parts from the Carter fuel pump and rebuild the old AC 429 that was on the truck for 30 years. I think it will work.