Try leaving the gas cap off for a bit , see how she does .:-X22 Best of luck !

I would probably get the truck towed since you said your on the side of the road. Do you have a daily driver? I understand you like working on your truck, but posting on here that your stranded on the side of the road and it's cold doesn't sound so good.

One more thought . My 78 has metal lines from front to the tank . rubber at the tank . AND a rubber union along the frame ! Years ago I had a problem with it sucking air from cracks in the rubber . It did not leak fuel , just sucked air . Just a thought !

well I just got it towed home. I'm going to go ahead and change all the rubber fuel lines again tomorrow just because I have about 5 feet of fuel line. I might also drop the tank and by a different breather because the breather on the tank is the only old part in the entire fuel system including the gas cap which is also old.

Fuel Pump
 

Hi, I agree with (JWC 3) That happen to my 1958 F250 after getting it towed home and lots of Frustration, it all boiled down to a VENTED GAS CAP. So try looking into that !! GOOD LUCK

Since you are all up in there dropping the tank again and all, you might as well at least blow out the hard line that run down the dvrs side of the frame.

Yes get a new tank top roll over vent for it, filler vent line clear? Try a vented gas cap. Are you running a fuse on the elec pump to protect it?

Get some extra gas on hand since it sounds like it will not have any in the lines if you do torch it, lol JK. Hang in there you will fit it tomorrow, let us know what it was.

Cracked fuel lines sometimes do not leak, but let air in.

when I put the electric fuel pump in yesterday I blew out the fuel lines into a bucket and it was totally clear. I've owned the truck about 5 months now and the same fuel lines have been working fine.

Maybe try getting your mechanical fuel pumps from a different parts store and try a different manufacture, maybe Dorman....Spector...Look up Rock Auto they have great prices.

Try getting it to run off a stock mech pump and out of a gas jug first....

both mechanical fuel pumps that I bought were from Napa. The electrical one that I just replaced the mechanical ones with was made by Mr Gasket. Probably not the best fuel pump but I was broken down and the parts store was right up the street and that's all they had as far as universal in line pumps. I might go back to mechanical once I fix this ventilation problem if that's what it is. I just find it kind of odd when I pressurize my gas tank I can hear the vent on top of the gas tank letting out air. is that vent/valve on top of the tank to let air in or out? I'm assuming it works kinda like a PCV valve. Maybe I should hook the vacuum up to it and put negative pressure and see if I hear the same noise going the other way.either way I'm dropping the tank tomorrow.

ok so I was just testing some things so maybe you guys can tell me what you think. The gas cap has a little hole in it where im guessing is the valve. So I put my air hose to it and it blows air out and it blows it out at a decent rate. Then I put my darn lips on that bad boy and sucked lol I know lol I sucked and well it breaths. Then I once again pressurized the gas tank with my air hose threw the fuel line that hooks to the carb. The air goes all the way to the tank and I hear the bubbles coming from the sending unit then I hear the gas cap letting the air out right away. Either way tomorrow im buying a new gas cap just to say its new. If I get a new cap that breaths both ways then would I really need a gas tank vent that goes on the top? im really not trying to drop this tank again.

You need to stop blowing into tanks....

Go back to the beginning, what did you do last "working on" wise to the truck before it started having this issue?

Or what has changed or has be adjusted incorrectly?

well so far today I exchange the fuel pump. And I bought a new gas cap. The new gas cap seems like it breathes even less than the old one but it's one more piece I can say is new the case I have this issue again. I still might drop the tank test event at the top of the gas tank. Also while reading instructions on the sand line electric fuel pump it says the place it within 12 inches of the fuel tank do you think that that really matters?

so I hook up a new fuel pump and I'm draining the gas tank. I have the fuel pump hooked up where it was before, instead of having it pumping into the carburetor I have the hose inside some empty gas tanks. so far I have successfully pumped out 9 gallons of gas with no issues. The truck failed in 3 to 5 miles before and that's no where near 9 gallons. I pumped the first 4 gallons of gas with the old fashioned Canandaigua it did just fine. Put the new cap on and it's still fine. what I do notice is when I hook the fuel line to the carburetor and turn the pump on the sound of the motor drastically changes because it's no longer free flowing its building up pressure do you think that's putting too much on my pumps for some reason? It's almost as if the pumps are pumping but the carburetors not pulling in enough fuel and it's tearing diaphragms and burning pumps? What do you think just a thought

Have you checked to make sure that the tank is venting okay? Run it with a vented fuel cap and see if it will run more than 10 minutes.

Is there a screen on the pickup in the tank? If so, it might be plugged up allowing fuel to gradually soak through it letting it start and run a little while, but I don't think that would cause what you're experiencing, but I'm trying to offer some thoughts that might lead you to a solution.

Hope this helps.