Gas fumes

gas-tanks
gasoline
pump
leaks

#1

My mechanic thinks the gas fumes are coming from

under the gas tank and wants to pull it. I think the gas cap is not fitting tight, and the lip is rusted around the seat for the cap. The fumes are only when the vehicle is running and warm. Car runs great otherwise.


#2
Well do you have a question?   :-) 


OK change the cap and see.  They are cheap.  BTW my guess is the vapor recovery system.  Of course I have never seen the car.

#3

Knowing the year, make and model of the car would help.

However, unless you’re driving a classic, any fumes should be going via a vent line to a charcoal canister. You should not be able to smell gas even with the rot holes you described.

I agree with your mechanic. You should not smell gas and the leak should be repaired.


#4

It’s a '95 Isuzu Trooper, 180K.


#5

Any leak around the gas cap would be immediately detected by the OBD system. It might take a couple of driving cycles for it to light the MIL but it should happen in short order.

I’d suggest you clean up the rusty lip before investing in another cap. I’ve done this before using some sandpaper intended for metal followed by some crocus cloth to smooth it out. Then a light coating of clear paint to protect it. Clean the cap gasket/ORing and see if the problem goes away. Much cheaper than dropping the tank so why not rule it out first?


#6

WHERE IS THE SMELL OF GAS STRONGEST? DO YOU SEE EVIDENCE OF GAS LEAKING UNDER THE CAR? YOUR CAR PROBABLY HAS NYLON FUEL LINES WHICH ARE FAMOUS FOR GETTING CUT AND THUS LEAKING. ATTEND TO THIS PROMPTLY MY FRIEND, YOU ARE IN DANGER. DAVE