Fuel leak....big one.

Got a call from my wife yesterday saying she walked outside and saw a huge gas leak from my 69 mustang coming from the gas cap.... she said she oped the cap and a lot of fuel came out under pressure..... now this is a first for me here... I just filled it up the night before and parked it on the driveway same as always but never had the tank pressurize in anyway like this.... I have the flip type gas cap on there..is this type a problem for others as well? This bothers me as it's a huge fire hazard so I cut a piece of rubber and inserted it inbetween the old seal and the filler to seal it off.... anyone have this problem as well? Jeff.

HI SOD
A coupe of things come to minde.
Over filled the tank, Car parked on a hill with the back on the down hill side (this would cause the gas to be in the neck of the fill tube.) I don't under stand the flip type gas cap??[img]/phpBB/images/smiles/icon_confused.gif[/img] OH [img]/phpBB/images/smiles/icon_eek.gif[/img] Do you mean the type thats conected to the body (GT stile)? I SEE..
Tim[img]/phpBB/images/smiles/icon_spin.gif[/img]
[addsig]

Most gas caps have a 2-way air valve that holds back fuel and fumes and also lets air pass into the tank when the tank gets under a slight vacuum. It may build a little pressure but not much (1/2 psi). If the gap gasket is worn it can leak fuel if it gets up to the filler neck.. Try not to fill it so full. I made me a nice rubber gasket out of an old 1/8" thick mouse pad to keep mine from leaking under a hard launch at the drags.
[addsig]

thanks, I cut one out of a piece of radiator hose for now, I only filled it up just like the other times but as to why it sprayed out of there when she opened the cap...that's a new one for me....... did not see how much I lost but that friggin gas cost me over 2 bucks a gallon [img]/phpBB/images/smiles/icon_smile.gif[/img] could be why I am only getting 8mpg anyway..... thanks Jeff.

Simple problem. When you filled it at night the gas was condensed. When it warmed up as the air temp went up, the gas expanded. 15 gal became 16 and so it pushed out. It's also how lots of carb cars get flooded in the summer heat and become hard starting. Due to the gas pushing past the pump and float needle valve.

If you have 15 gallons of gas, for every 10 degree increase in temp you gain 2 tenths of a gallon.