HELP My fuel filler line is KILLING ME...(so to speak)

Ok, so my 2000 ford f150 WILL NOT let me pour gas into it for more than 5 SECONDS without it turning off the fuel dispenser handle and or spilling back gas out of the filler opening…It’s not too bad for a PATIENT man/woman that doesn’t mind spending 25 MINUTES to pour in one gallon of gas!

Ok, that was an exaggeration (I’m frustrated lol). But that ‘is’ the problem. No matter what angle I try to put the nozzle, doesn’t matter. Now, truth of the matter is IF I can hold the dispenser open just enough to let gas TRICKLE into the filler pipe, I’m good. But that literally takes like 25 minutes to fill the tank.

So first question is: Any idea’s or suggestions? (THANK YOU!)

Second question: Can anyone explain the purpose of the air line that goes down the side of the fill pipe into the gas tank? I assume it is to let air out of the tank as gas is put into the tank. But here is why I ask: The air line that comes up out of the top of my tank…goes up above my gas filler pipe, and then drops down parallel to the gas metal line. In other words the rubber part of the air line seems to be too long to just lay across the top of the tank, beneath the gas filler metal line. I was wondering if that might a problem. Any help or suggestions is greatly appreciated.


The line that goes down the side of the fill pipe is part of the Evap system that recovers gas vapors and also allows the tank to ‘burp’ when filling. Do you have any check engine codes? Sounds like you have a bad evap system that does not allow the air/vapors to come out of the tank making it hard to fill the tank. This can be caused by continuing to fill the tank after the pump clicks off-when the system is operating normally. Get your truck to your local mechanic and they can give you a price to fix this.

Ok Thanks Steve. How does a mechanic fix a gas tank that doesn’t allow the vapors to escape through the air line? Any idea?

It seems to me in a closed system when fuel is added and their is a hole for air to escape, that air and or vapors MUST go through that whole to escape, based on the physics of the fuel taking up the additional space. (of course I never took a physics class lol).

I meant ‘there’ not ‘their’. Lol. I did take an English class.

lamoore : read Steve’s post carefully. I fully agree with “This can be caused by continuing to fill the tank after the pump clicks off”.

Be VERY careful in the future when you fill the tank, or allow attendents to fill the tank. You must stop at the first click. Do not add any more gas.

Bottom line, you need to have this repaired by a qualified mechanic. The system may be damaged by overfilling.

+1 to everything that Bill Russell stated.

Have someone remove and inspect the vent valve and it’s hoses for a restriction.

The EVAP system in your vehicle allows the gas tank to vent air while the carbon canister absorbs any fuel vapors. These fuel vapors are then burned in the engine when the computer commands the purge valve to open.

Did you know spider’s nests in these systems can cause the problem you’re having?


Thanks Tester. Ok, here is a (broke) mad-scientist question: what if one were to just disconnect the air-line that runs parallel to the fuel filler line? There is about a 9" rubber hose attached to the top of the fuel tank. It connects to the metal filler assembly. What if it was left disconnected?

Hopeful prediction: It would work perfect! It would let air out while you are filling it with gas, and it would let the vapors out all the time. Lol.

That will cause the Check Engine light to come on.

You want to fix this the proper way.


Ok, thanks Tester. I agree, and will.

+1 to Tester. I’ll bet your check engine light is on now.

There is a float shut off/roll over valve in the top of the fuel tank that may be stuck. The valve normally vents to the charcoal canister until the tank is full then the valve closes, venting stops and causes the fuel pump nozzle to shut off. This is not affected by over filling the tank, that is a myth.

That’s the way it used to work OP, when you refilled the gas tank in old cars any air in the tank would just vent to the outside air. But now-a-days the EPA doesn’t allow the fuel vapors residing at the top of the tank to be pushed to outside air during re-fueling. They have to be directed to to the charcoal canister and stored there for later re-burning in the engine instead. While it seems a simple thing for the car designer to do, yours is a pretty common complaint we see here, so maybe the manufacturer’s haven’t got all the bugs out yet. In any event, it shouldn’t be overly difficult for an experienced shop to diagnose and fix.

Do you “top off” your tank?
As already described, when you fill your tank the air inside the tank, ripe with hydrocarbon molecules (airborne gasoline vapors) in modern cars is diverted through the charcoal canister. The hydrocarbon molecules get captured by the “activated” charcoal (that means it’s been bathed in acid to make it highly porous) and the air (nitrogen, oxygen, and misc) is then vented near the gas fill hole. When you start the engine, your vehicle’s computer opens a “purge valve” to allow the hydrocarbon molecules (gasoline vapors) that were collected by the charcoal to be drawn into the engine’s intake and burned.

If you “top off” the tank, you can on some vehicles saturate the charcoal bed with gasoline, prohibiting the tank from being able to breath out. Can’t breath through a wet bed.

Newer vehicles have systems designed to prevent saturation of the charcoal bed, but I don’t know that your 2000 has. This includes a diaphragmatically operated “refueling valve” with a restrictor orifice as well as a float-operated valve in the line from the tank to the charcoal canister. The float valve shuts the line off when the tank is full as well as causing the pump handle to trip. The refueling valve controls the rate of flow of gas-rich vapors to the charcoal bed during refueling.

My guess is that your charcoal bed is saturated.

If you DO have a check engine light, see what that tells you. That’s always a good place to start.

That’s a very good description @“the same mountainbike” . I gained some add’l insight of how this works from you post, thanks!

You’re very welcome. I try to pass on what little understanding I have when I can. :smile: