My 76 F100 has a single 18 gallon rear tank that has an Evaporative vent/charcoal canister. I am having a tough time getting gas into the tank without it sloshing back out the filler. Today I got about 12 gallons in and probably left a pint or more on the ground doing it.

I am leaking from the smaller hose between the tank and filler at the hose clamp (I have tightened).

I was reading about vent tubes to the charcoal canister being blocked, so I took my air hose to it, disconnecting the tube from the charcoal canister and putting compressed air back toward the tank.

I'm not understanding the function of the smaller tube between the tank and the filler tube.

I don't have any problems with the truck getting fuel to the carb and running, just getting gas into the tank when it gets close to empty.

I am somewhat tempted to get a 38 gallon replacement tank. If I were to do than, what would I need to do as far as a sender/pickup tube to work with my stock dash gauge?

 

Tanks with the filler cap on the out side of the box are hard to fill . My 73 is the same way , the four different 79s i had were not that way but they have a cover lid on them. Just have to put the fuel in a little slower and not try to lock the fill nozzle at fast speed.

 

Rear tank would imply its not the external filler neck. Evaporative systems are for vehicles that do not have the charcoal canister, so actually you should have the non-evap system and the sealed fuel cap, I believe.

You kind of contradicted yourself diagnosing the possible problem, but it doesn't really matter for my suggestion anyhow. First you described it as "sloshing" back out the filler, what I call "burping", and then you describe a possible leak situation, which is a completely different problem but the solutions are similar. Either way, read on.

Replace the rubber hoses between the filler and tank, but the vent is probably your problem. The function is like this: Picture shotgunning a beer. If you open a beer and tip it fully up, it gushes into your mouth and you burp a lot after because of all the air that also entered. If you poke a hole in the end of the can, the beer now flows smoothly and you've swallowed much less air. It's a vent that allows the gas to flow smoothly and replaces the displaced air.

I don't know exactly what the 76 setup is, but its probably just the rubber hoses that need replaced. It'll be much easier to drop the tank to do the job, but I believe that it can be completed with the tank still in place if you absolutely have to. I'd also replace the rubber line from the charcoal canister too, can't hurt.

 

You can invert or rotate the gas nozzle upside down and even then you can not go full on, on the pump handle.

Yes sounds like you need to replace the small vent hose from the back side of the filler neck and then connection port on the tank. PITA on the tank end without dropping the tank.

New 38 gal tank, you either lengthen the float arm (how correctly?) or get a new sending unit specifically made for the 38 gal tank.

 

Heres a link to my build thread, I put a 38 gal tank in my truck. Not much info on the sender since the guy I got the tank from had already done the mod. Pretty much step by step on the tank install though.




https://www.ford-trucks.com/forums/1...4bt-build.html

 

I put a 1978 Bronco 25 gallon tank on my '74 supercab and it fits well. Couldn't use the original or stock Bronco straps so I used straps from a '73-up Chevy Suburban with a 25 gallon tank and after a little modification to the ends plus some spacers, it worked fine.

 

You didn't say what part of the world you're in, but there are some places (like CA) where vapor recovery nozzles are used on the gas pumps. Whenever I tried to fill the tanks on my '76 F-250, I got the same results you described. As soon as I got to another state where conventional nozzles were used things got much better. It's hard to understand how the environment is helped when a pint of fuel is on the ground when it doesn't have to be.