Dear Car Talk: I have an issue with my 2005 Ford F-250 Super Duty that's causing me to lose my sanity. When I am getting gas, the gas does not flow down the filler neck at a fast enough speed. It backs up and my nozzle gets automatically shut off -- as if the tank is full.
The real problem is that this happens every gallon or so when I am getting gas, meaning the nozzle is clicking on and off every minute or two until I am done filling up! This is driving me cray-cray. PLEASE HELP! -- Fredd
But is it driving you crazy enough to spend money to fix it? Because then I'll believe you, Freddy.
Usually, when you have trouble filling the tank, it's related to the evaporative emissions system. When you pump gasoline into the tank, the existing vapors in there have to go somewhere. They used to just come right out the filler neck and into the air, but that caused smog and asthma, so we put a stop to that.
Now the vapors get pushed into a charcoal canister, where they're stored until you start the engine and they can be combusted. But if the vapors can't get into the evaporative canister, for whatever reason, they push back up the filler neck, and signal to the fuel nozzle that the tank is full and it's time to "stop pumping."
How do evaporative emissions systems malfunction? If you overfill your tank regularly -- if you keep squeezing in 94 cents more gas so you can get to a nice, round "$50.00" on the readout -- liquid gasoline can get forced into the charcoal canister and plug it up. So that's one possibility. There's also a solenoid that controls the valve to the canister; that could be bad. And finally, there could be something mechanical, like a kink in the tubing that runs from the gas tank to the canister.
So, you need a good mechanic who's willing to do some diagnostic work for you, Freddy. And depending on what he finds, the cost could be anywhere from $100 to $500. If it turns out to be too much, you can always stick with the stop-and-start fill ups, and console yourself by thinking about what a great workout your hand muscles are getting.
Good luck, Freddy.