Mechanical Fuel Pump Issues

Hi, I have a 58 CJ5 with the stock motor, and the non glass top mechanical pump. I have pulled the pump and checked it made sure it was clean, unbolted the top and cleaned that too, had some sand from the tank in it. I is still not pumping.... I am getting nothing to the carb and really it is not even filling up the fuel pump bowl.

I noticed that the arm that rides the cam has very little wear on it, I have been reading that having the spacer on it lowers the fuel pressure, so if I take the spacer off and put the pump back in I should get more fuel moving through the pump.

I can move the arm on the pump and I hear it suck in air, so if my arm is not moving up and down on the cam then it would not be pulling vacuum. I really doubt that my cam lobe is worn out, I have a new carter pump coming but wanted to try some stuff before it got here.

Am I on the right track here or is my cam lobe shot?

 

Turn the engine by hand and get a look at the cam lobe itself. I'm betting it's probably OK, but see if you can get a camera and a light lined up to take a couple pics and post here for folks to see.

I had a similar issue with an AC Delco all metal dual action pump (no spacer) that I, and others couldn't troubleshoot so it was rebuilt... and then it leaked badly out of the single cap bolt on top regardless of what gasket was used. Go figure. I was able to find an NOS glass bowl dual action pump (needed spacer) and it's worked flawlessly for 2 years.

The use of the fuel pump spacer is covered in pretty good detail on the CJ3B page and has all the measurements for when to use and when not to use. If I recall, it's not just a matter of the pressure changing, but also that the spacer is needed in some cases to make certain pumps fit right for any function at all. Some pumps have a sliding "foot" on the end of the arm (my words), some do not. Some have straight arms to the cam lobe and some arms are angled and that might also determine the need for a spacer.

 

Been wondering about those spacers, and Tony's description of their purpose is as good as any I have heard.

My 67 has sat in storage since 1979 so I am replacing the pump. I pulled the old one yesterday, it is the one with the glass bowl top, and it did not have the spacer. The replacement pump I have has the metal top. I will compare the arms on the two before I install it. If the same I will assume I don't need that spacer, and if they are different I may use a spacer.

 

Here's some info about spacers and fuel pump rebuilding from the 3B page: Willys Fuel Pump Installation at CJ3B.info

 

When you reassembled the pump did you pre-load the diaphragm and hold it while tightening the screws? Failure to do so can result in very poor performance.

 

I am not sure how that would be accomplished, it is a metal top with no access to the Diaphragm.

This is a single action pump since it has electric wipers. I'll pull it back out and measure the arm and see if I need the spacer.

Thanks for all the input.

 

I'm sure you've already done this, but make sure you also blow some air through the line to the carb to make sure it's clear. Also blow some air through the line from the pump back to the tank to make sure that line is clear. If you had some debris in the pump, there may be more elsewhere. Are you running a fuel filter between the tank and pump?

 

Yes, clear filter, and have cleaned the lines both ways in and out of the pump.

Thanks,

 

If you pull the dipstick does the oil smell of gasoline?

 

Connect the pump to the fuel line from tank only and cycle the pump lever by hand and see if you get fuel.

 

You may have some debris in either the inlet or outlet valve. If one of the valves isn't seated, then suction/pressure can't form.

 

Check the tank for the fuel pickup to be plugged. I had that happen and thought it was a fuel pump.

 

whaddya mean pickup? as in where the line connects to the tank?

 

Yes, there's a horse shoe piece of tubing that goes up in the tank then back down to the bottom, maybe 1/2" from the bottom of the tank. You don't want to suck directly off the bottom. I used a piece of steel wire to clean it out.

 

I had a replacement pump fail to deliver fuel after a few years.
Removed it and took it part and found one of the valves had become unseated.
reset it and staked it in place, no issues 3 years later.
Unseated valve on right:


repaired:


Granted, this is not an F-HEAD pump but shows what I had to do to make it work.

 

It is the standard procedure for assembling the fuel pump. You are only looking at the top cover plate. The pump has two main sections, the mechanical section with the pump arm in it at the bottom. Attached to the pump arm is the diaphragm. This section is covered by the pump valve chamber which is attached to it with screws. On top of that is the cover plate. If all you did is remove and reattach the cover plate, then no problem. When reattaching the valve chamber to the mechanical base the pump arm should be clamped in a vise such that the pump can be pulled back to a full stroke. Holding the pump in that full stroke, the screws can then be tightened. This places the preload on the diaphragm.

 

you can pull it apart, i did it. i have the same pump. all it takes is a little looking and a few basic tools

 

I was working on a Morgan Three wheeler with a Ford Tractor motor in it. Someone else had put the motor in the Morgan. The carb would flood over when it started, I looked around in the box of parts found a fuel pump spacer. I put the spacer in and problem solved, without the spacer it over stroked and made too much pressure for the needle and seat and caused it to flood. Just a thought, it worked for the Morgan. Good Luck.

 

Thanks for all the help, my new pump is coming in tomorrow, and I hope it works...