I am ready to start the falthead, and I can't get fuel pumped up to the carb.
I have pulled vacumn on the lines, and can hold 10 in Hg for 3 minutes, I have filled the bowl, and sucked fuel through the pump to make sure it's primed. I have replaced the diaphram in the pump, and the pump rod. I have aspprox. 2 lbs preasure on the stroke discharge of the pump. If you pull the pump off of the engine and work it by hand, I have more than enough vac amd pres to pum fuel to a 512 linc. But when I install it, I can't get it to pump. The only thing I havn't done is check the stroke on the rod, I'm going out to do that next. Any other ideas or things I might have missed?
Any help will be appreciated.
Howard

 

I have a 46 Ford truck with a 100 HP flathead that had the same problem that you are describing. Even with a NOS fuel pump, it didn't want to pump fuel. The fuel pump push rod runs off a lobe on the camshaft. That lobe is known to wear, thus shortening the stroke. I tried out a trick that was passed on to me by a retired Ford mechanic and it worked for me. I cut out a piece of leather with a common paper punch (out of an old leather belt about 1/8" thick) and pushed the cut out up into the arm on the fuel pump where the push rod goes. The leather lengthens the stroke without wearing the push rod or the fuel pump. The piece of leather eventually wears out and has to be replaced. Another option would be an electric fuel pump.

 

With an almost new cam, and a new pushrod, I can't see that as my problem. I have done some more research and can provide a little more information, if someone can decifer it for me.

There were two push rods used. one for an "aluminum valve chamber cover" ( i don't know what that is) it was 7.872" long. one for a "cast iron valve chamber cover" it was 8.872" long. I know that I have the one that is 8.872 inches long, I know that the oil fill housing is cast aluminum.

I know that the throw on my cam is almost 1/4" When I get some one to help me, I will get the exact throw, but as close as I can tell, trying to read the dial over the radiator and crank the engine with the wrench, that's what I get. The leather trick should work, if I don't have too long of push rod, and I've maxed out the stroke of the pump.

I am using the stock 59A fuel pump, but have a spare R series available, but know that it wasn't original to the truck, and don't have any fuel filter.
Thank you in advance.
Howard

 

It sounds like you've got the right combination in cam/rod/pump. I put a new one on a 52 project truck last summer and had the same problem. Eventually I primed the pump by pulling gas from a fuel can sitting on the cowl. Once I got gas flowing thru the pump it's been fine. Might be worth a try.

 

i've sucked gas clear up through the pump, so I guess I could try it. If I understand you correct, you primed the pump with gravity flow?
Howard

 

Basically, yes. It had to lift a little - just not as much distance as it has to go from the frame rail up to the pump. Now that I think about it I believe I had the can sitting on the fender - 'bout the same difference.

Your line connections are all tight from the tank to pump? Also, you have a vented cap on the tank? It doesn't take much air entering the line or an airlock in the tank to stop the flow.

FWIW, I always run a plastic see-thru filter just before the pump. The pump screen doesn't get the fines out and you don't want them in the carb. Also, if you've got air in the line you can see the bubbles in the filter. NAPA Gold 3002 is what I use.

 

Lessons learned from a fuel pump.
I would guess that the truck this pump come out of was last run in the 1960's. I took it apart, cleaned and inspected it, installed a new spring, diaphram and reassembled it. Don't know who made it, or who it was bought from, but was obviously a cheap replacement for the original. I disassembled another pump off of another engine tonight, and the quality of the casting, and part fit was much better, took diaphram, and spring out of the rebuilt, and reassembled with new parts, I know have fuel. Thank you for all of you help.
Howard

 

Howard, on the Fuel Pump problem. Did you recently have your engine rebuilt, I read something in this post about the cam.
The reason I ask and I hope that I am wrong for your sake, but I had the same problem with a fresh rebuild.
I see that no one has touched on this, here goes. The rear cam bearing was not installed properly, by this I mean that when the cam lobe pushed up on the rod, it stayed there so the fuel pump was not going through the cycle.
We loosened off the 2 bolts that secure the pump to the stand, pushed the pump up and down and the presure that came from it was as it should be.
To find out that the rear cam bearing was not allowing the rod to drop back down, as I said I hope I am wrong but that happened to me.
Take the pump off and have some one turn the engine over while the push rod in down inside where it should be and hold pressure on it.
It should while the engine is turning go up and down. Is there any slack in the fuel pump arm, to the point where it should be replaced with a full rebuild kit, and one other thing as another mentioned are there air bubbles in the sediment bowl, if so the the bowl isn't seated properly.
Keep us up to date, and I sure hope it isn't the problem that I told you I had, good luck, I mean that.

 

I rebuilt the engine, and have yet to start it, I think I now have it 180 deg out of time. I will attempt to get it started again tomorrow. I now have fuel, the problem was the fact that I rebuilt a cheap fuel pump, it didn't have bushings in the rocker arm, the casting wasn't machined smooth, and the spring was inferior. After cleaning up another one, and putting it back together, I have more fuel than the two barrel will use. Thank you for the advice though, i've rebuilt several engines, and have never had a cam bearing in wrong, but I can see how it could happen with the way it sets in a flathead.
Thanks again
Howard