Gas vapor in car

Went to put gas in a friends car. When I stated the car, the car immediately filled with gasoline vapor that went away after a few minutes. This happen twice after the car was filled. Is there a gas leak somewhere? Is it safe to start the car (I would say ok since it has not blown up)? What is the fix?

Is it safe to start the car (I would say ok since it has not blown up)?

Of course it’s unsafe. It’s said to be fairly difficult to get gasoline to explode, but starting the car would be asking for trouble.

The safe thing to do is to find a mechanic that is willing to work on the car and have it towed to his shop. Call first. Some mechanics possibly won’t want anything to do with the vehicle as they can find plenty of less risky work.


If you are determined to look at this yourself, check the pavement under where the vehicle is usually parked for stains from leaking gasoline. Likely sources would be the EVAP system emissions control plumbing, the fuel fill pipe, the fuel pump (usually mounted in the tank nowadays) and the fuel line(s) from the tank to the engine which may have a fuel filter in them. Look for damaged fuel system components, split rubber hoses or severely rusted metal lines.

Many Asian cars have an panel under the back seat that allows access to a plate on the fuel tank that holds the in tank fuel pump and fuel level gauge. If either of those have been worked on recently, it may be that a flexible gasket between the plate and the tank is improperly placed or the one or more screws holding the plate is missing or loose.

My guess is the tank is overfilling and some raw gas is going into evaporative emission system. You can try filling it at a slower gas flow setting, once the pump clicks off stop there, no more gas in the tank!

If that does not work if you know it will take 12 gallons try putting in 10 and see if the problem reoccurs.

This only happens just after filling the car if I read it correctly.