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Cannot fill gas tank, 2000 formula firebird

I have a 2000 Formula Firebird with ~90k. A year ago while trying to fill the tank, the fuel overflowed and spilled on the ground. The dealer talked me into replacing the tank…months later the problem happened again. Brought it to the dealer and was told I needed to replace the tank… Went for a second opinion and found that the tank would fill again. It has happened again yesterday, I let it sit overnight and sure enough…it can be filled. The service engine light comes on when the tank is 1/4 down then goes off. Any help would be appreciated.

It’s more likely that you have a kinked vent hose, or that you have a bad valve in the hoses for the evaporative emissions system, or that the carbon canister for the evaporative emissions system is saturated with gasoline. The latter scenario is very likely if you have been in the habit of forcing more gas into the tank after the pump shuts off for the first time.

Would any of these scenarios cause the “Service Engine” light to illuminate? Thanks for your reply!

Yes, either one can. Modern cars have vapor recovery systems to prevent gas fumes from leaving the tank. They can be messed up several ways but the favorite two are a kinked hose or a damaged charcoal filter. The charcoal filter can be damaged by topping off the tank when you fill it. Most cars have a warning bout that in the owner’s manual, glove box and/or the fuel filler lid.

If you have a habit of topping off the tank after the pump kicks off the first time, you are likely the cause. 

Good Luck

I know I do top off…so that could be the problem. This is a practice I’ll discontinue!!!

Unfortunately, you will be “locking the barn door after the horse has been stolen”, to use an old expression. Promising to be a good boy in the future will not eradicate the damage that you may have done to the carbon canister on this car. If I am correct about the carbon canister, the replacement will cost somewhere in the $300.00 range, so that steep tariff may keep you from ruining the next one!

Incidentally, this is a very good indication that those decals on the gas cap or the gas filler door warning you about not overfilling the tank should be taken seriously.

And, when posting a question about a car problem, it is a good idea to include ALL possible information. By leaving out the detail about the CEL, you did not make anyone’s job easier.

Good luck with the repair!

“And, when posting a question about a car problem, it is a good idea to include ALL possible information. By leaving out the detail about the CEL, you did not make anyone’s job easier.” I think he mentioned the “service light”.

When the cap is off, the tank is vented out the filler, period. There is a check valve or check ball that can jam in the closed position and prevent normal fuel filling. Use the search feature of this board to get the details…

You are correct. My apologies for this oversight.