Fuel pump push rod throw

tintoptexan

tintoptexan

Member
I am having problems with my fuel pump. The engine is a 1947 model 59AB in a 40 merc convertible. It is dressed out as a 40 except for the distributor and coil. There doesnt seem to be enough throw on the push rod. I checked the length of the push rod and it is as required, 7.87 with an aluminum manifold. Does anyone know what the travel is for the rod? I'm hoping that the lobe on the cam is not worn. The pump does not leak and working it by hand, it will pump with long strokes. Any help will be appreciated. Thanks, Joe
 
It use to be very common for the fuel pumps on the flat head V8's to not work properly because the fixture that the fuel pump was mounted to either had bent from years of use and/or the mounting base was to thick. All of these conditions were solved by filing the base flat and/or removing some metal from the base with a mill file.

Another trick was to place something within the cup on the fuel pump where the push rod rests within the pump. A piece of leather cut from your belt usually did the trick.

As a last resort the engine was torn down to check for a flat cam, which was usually not the case because the real culprit was the aftermarket aluminum manifold and/or a worn out fuel pump.

An old flat head Ford V8 without an electric fuel pump is a failure waiting to happen.
 
Agree with the <1/4" measurement. Not a lot of movement. Try the leather in the cup idea before you do anything else.
 
blucar said:
An old flat head Ford V8 without an electric fuel pump is a failure waiting to happen.
Click to expand...

Considering all the talk of failed electric fuel pumps I've heard lately, I think you could possibly reverse that statement and it would be just as true!

"An old flathead Ford V8 without a mechanical fuel pump is failure waiting to happen."
 
The spec for the push rod lift is 0.200" (just under 1/4"). If the cam lobe is worn, a new pushrod will not help the stroke enough to move the fuel pump diaphragm as it should. Insert push rod, rotate engine and measure with a mic to find the top and bottom of the stroke on the pushrod. The difference should measure darn close to 0.200".
 
Few months back I was thinking I had issues with my push rod but after returning two repro fuel pumps I finally figured out it was the fuel pump.

My push rod was fine, exact length it should be but the new fuel pumps they make for these flatheads were off bigtime.

My third fuel pump worked.
 
RBaker said:
Few months back I was thinking I had issues with my push rod but after returning two repro fuel pumps I finally figured out it was the fuel pump.

My push rod was fine, exact length it should be but the new fuel pumps they make for these flatheads were off bigtime.

My third fuel pump worked.
Click to expand...


After your third pump ?!!? care to share where they came from?
 
Thanks to all for the great responses. I did get the 40 going and as posted by RBAKER, mine also was the fuel pump. Not a rebuilt, but the one I had been running. Found a rebuilt through O'Reilly's and so far so good. I also put a 6 volt electric pump on a momentary toggle switch to prime with after it sets a while. Cuts down on the cranking time. Thanks again. Joe
 
32Gnu said:
After your third pump ?!!? care to share where they came from?
Click to expand...

I ordered them all from carquest.....not sure where they got them but I would bring one home and try it out then take it back and tell them to get me another one at no charge.

Eventually the third one worked like a charm....the other two had a lot of play in the pump arm so my push rod would not have enough travel to pump the fuel pump as it should.

I had removed my intake and measured the push rod and knew nothing was wrong with it.....also my old fuel pump that had probably been on the truck for 40+ years still worked but it was not the correct pump for the truck since it had a glass sediment bowl on it.
 
Guys,
I am having a similar problem w/ my "60" engine in my vintage midget. Does anyone have the fuel pump rod "throw" for the V8-60?

thanks
OlRacer
 
A proplem part that gets over looked is the rubber hose from fire wall to pump.The hose will get soft near the middle (caused from motor movement) and the pump will suck it together.
 
Hello everyone this is my first time to the forum, I recently bought a 1936 Fordor humpback sedan. The gentleman that I bought it from did some work to it but I’m not sure exactly how much of it is original, the push rod that I pulled out of the engine was 8.78 however I have a aluminum manifold which says it should be 7.87 inches long, he did however have a electrical fuel pump connected , my question is will the mechanical fuel pump work properly if I leave the 8.87 in there or should I put the shorter one which is 7.87 with a new mechanical fuel pump ?? On a different note how important is it to have the baffle that sits under the fuel pump stand or known as the ventilation tube?
 
Coolguyanda36Ford4dor


I am a BIG proponent of having it "as it should be" SO to answer your question I would get the correct length rod and have it as Ford built it. I for one also disagree with bluecar's post above in that NOT having an electric fuel pump is a recipe for disaster.......I understand many, like yours, rational for the electric pump...BUT...I have the "As Ford built it" set up on my 39 Mercury and week in and week out it performs flawlessly. I live in Florida thus I try to drive it weekly BUT there are sometimes that it sits for three weeks or more, STILL, with absolutely NO issues. Sure, over that lenght of time is spins a little more than normal to get the fuel system filled back BUT still has NEVER failed to start within 20 seconds or so!!!! NOT too excessive I don't think. Anyway JMO
 
Coolguy, your 8.78' long pushrod is the correct one. The statement you have read that states the 7.78 long rod is to be used with aluminum manifold is not entirely correct; depending on the manifold, there is two different heights of the mounting flange for the fuel pump mount, 1" difference between the two. If you had the lower mount style, there is no way you'd be able to assemble the pump in place if using the longer, 8.78" pushrod!!
The baffled ventilation tube affair is vital to have installed, as it directs crankcase ventilation down, through the crankcase, from where it circulates, moving up through the valve chest and exiting at front bottom of block. Without the baffled tube in place, the ventilating air can simply 'shortcut' straight through the valley and exit...
 
There are different aluminum manifolds - with different fuel-pump stand heights (and therefore different push-rods). As long as you have the right pushrod and pump stand for the given manifold, the mechanical fuel-pump should work. With that said - I'm assuming the cam lobe is in good shape. Some of the modern after-market fuel-pumps have way too high of a pressure spring in them . . . which may overflow the carb's float and needle assembly. You should only have about 2 lbs of fuel pressure at the carb.

What I like to do is to find an old/original fuel pump and then have 'Charlie NY' (on this site) rebuild it as it should be. He'll put the correct diaphragm material in it, the correct spring and will test it to make sure it is good . . .
 
Thanks guys for all your great answers looking back the shorter push rod 7.87 would definitely not work , you can’t even see it sticking see out of the fuel pump stand, looking at the new fuel pump it doesn’t look like it’s rebuilt to the best of quality might just get a rebuild kit and rebuilt the original myself,
as far as the ventilation tube/baffle I just received it and the flange fits really nice on the bottom of the fuel pump stand however the tube that gets lowered into the intake manifold is too big it does not fit into the hole, help please Trying to upload a picture of it
 
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