I have had this problem since I put this truck together, have read on here of others having the same problem, so maybe someone can help me out here. No reason to put a year to this truck as I would have no idea where to start, so it is a F-250 4X4 460 bored 40 over, stock cam, straight up chain, which I assume makes no difference in getting fuel to thre filter. Before today I had installed 2 used mechanical fuel pumps, and one now electric pump from Advance auto parts and still never enough gas to run 4 barrel up a long hill, it will just run out of gas. So I'm on vacation and figured out I have to get this thing running right or sell it. I bought a new gas tank, nice and shiney inside and out(old one had a little dirt in it) new guage and pick up for it, (built the last one out of two) replaced the fuel line tank to fuel pump,( used 3/8 gas hose as I really did not think there was anything wrong with the steel lines and will re-use) new mechanical fuel pump, and new 3/8 hose from the fuel pump to a new filter and on to new edelbrock carb. what am I missing before it goes up for sale ?????? Yes it is the one in the picture. Thanks for any help in advance.

 

Well, is it airtight?

 

What about "vapor bubbles"? I've heard of something like this happening if the fuel lines get heated up too much and fuel vaporizes before it gets to the carb.

 

Close, but it's called Vapor Lock. :thumb:

 

How many psi are you putting out at the carb end of the fuel line?

 

A lot of stock 460's would do this when they new.
The cure holley used to have a high volume mechanical fuel pump.
larger motorhomes came stock with a high pressure and volume electric pump and a pressure regulater at the carb.

 

Well, is it airtight?

__________________
You can call me "Jerm" or "Jer" ...or just call me Chad!

Yes to the point tank is full, all clamps are tight.

Quote:

Originally Posted by Furyus1
What about "vapor bubbles"? I've heard of something like this happening if the fuel lines get heated up too much and fuel vaporizes before it gets to the carb.

Close, but it's called Vapor Lock. :thumb:

Never got hot enough today to be vapor locking.

How many psi are you putting out at the carb end of the fuel line?

Going now to check Rolling 10 to 15 seconds got a whopping 2lbs pressure at the carb, same before the filter.

Anyone know if the fuel pump ecentric is the same on truck and car engines ?

Thanks

 

2psi ? That's a tad low - it should read 5-6psi.

Correct fuel pump should be available - try going that route?

 

The new fuel pump i installed today was for a 1974 F-250 460 engine and took it right out of a stapled box. last 2 used pumps did exactally the same ? I find it hard to believe 3 pumps and 1 electric pump do the same thing. still feels like something is being missed. Guess I'll check out summit for a hi volume and regulator. About the pump ecentric do you know if a car 460 would be the same ?

Thanks

 

This is just me thinking off the top of my head... But,it seems like the eccentric is the logical place to be looking. But I wouldn't think that it would be due to wear. The eccentric isn't made out of that thick a metal. With the amount of pressure loss you have it would have to be worn clear through in spots. and I would think that one of the pumps you have pulled off would show some signs on the actuator arm. I would think more about it maybe being loose. But I could be all wet too!!!

 

Are you sure you installed the eccentric arm in the correct position?

Have you modified the fuel delivery system in any way?

 

I know the eccentric is good as this engine was just put together front for the 2nd time as we went back in to check that it was torqued to spec when the first 2 mechanical pumps did not work, that was when I purchased the electric pump to install and it did exactly the same thing, that got me thinking maybe when I was sliding hoses on the metal lines that maybe a slice of hose went inside the steel line and was closing it off when fuel hit it that was why I used a now one piece 3/8 hose to eliminate a bad hose.
When I installed the pump I am 110 % certain the pump arm was under the eccentric as I had to lift up on the pump to install the bolts.

 

Have you got the electric and the mechanical both hooked up.
Where did you install the electric pump.
Is it possible it is suching air on top of the tank.
Does it have one tank or two.
I dont know about a car but an E250 arm is a lot different than an F250.
Have you blown back through the line to see if the sock in your tank is plugged.

 

Only the new mechanical pump is on the truck. The electric one is in the shed.
When the electric pump was on it was by itself, never at anytime did I try both pumps at the same time.
The electric pump when installed was about 15" from the tank mounted to the frame.
I installed the new sending unit, I know it sits on the bottom of the tank. tank is full with 24 gals.
I am going to hook up the electric pump to a can of gas and battery to see what kind of pressure it has today.
I did not use air pressure to blow back through the system.

I'm thinking the arm on the pump is wrong but I have had 2 different ones on it so far.The one on it is really close to being straight,same as orig from donor truck, other was from a car, not so straight, but same problem.
Then again I remeved the electric pump for the same reason, it still starved for gas.

Thanks

 

Just tested the electric pump fron Advance stated on the side 5.5 to 9 psi. best I can get is 4.5 psi. Going to advance to see if I can get one that is at least in the middle of the 5.5 to 9 psi.