I am a rookie mechanic but I filled up the tank a day ago and drove it home. When I got back from work I smelled gas and found two 6 inch puddles under the car. One below the headlight vicinity and another a few inches farther away near the radiator. I cleaned them up, crawled underneath the car and couldn't find a leak. I checked the fuel pump and around it, I ran the car and nothing leaked. I looked early this morning to see if it had leaked overnight and nothing again.... How bizarre is that, I wouldn't think fueling it up (I did top it off near the top) the night before would have anything to do with it. Any ideas??? Thanks in advance.

 

I will reach for the fun of it, could a return line be open up front, and when you filled it gas sloshed up and leaked out?

 

I had the same thing happen this past summer. Was on a road tour and every time stopped I would top off the tank, squeeze in as much gas as I could. Pulled into the hotel parking lot, turned off the car and my wife asked why there was the gas smell. A mixture of gas and I don't know what was flowing out the from behind/next to the drives front wheel. Made a call to a buddy who is a retired mechanic for chevy. Told him what happen, first thing he said "you're topping off the tank, aren't you". It turns out gas was getting into the evap canister and the mixture was gas and charcoal. Now when I fill the car I give it one pull after it click off. Have not had this problem since. By the way I have a 78.

Thanks Bill

 

Bill
Thanks, I had a sneaking suspicion it had something to do with me filling it up too high. That is good news, I hope that is all the problem was. I was getting a little pissed off last night. Seems like everytime I fix something, something else breaks.

 

Not so much a problem with topping off, as fuel slosh from side to side in turns is the reason the line going to the evap canister is allowing fuel to enter that line going forward, because that little black box up to, mounted on the tank is defective, the internall float ball is allowing fuel to get into the line going forward.....call it a air/fuel separator......

AND in reality, that evap canister really should not leak all that much anyway....the thing is very old now, so check there too, PIA to get at no question

 

Hi Tim,
I don't think the vapor canister is the culprit… it's at least 3 1/2 feet to the rear of the spots you describe. To get that far forward the gas would have to be running out of the canister and along the frame rail and then onto the frame extension and on to the front cross member and THEN dripping on the ground. I CAN'T IMAGINE that happening
I think something else is going on…. but I don't know what? I don't know how that much gas gets that far forward and forms wet spots much less puddles.
Was the car parked nose down on a hill?
Regards,
Alan

 

Thanks for the reply, no it was parked level in my garage. I litterally topped off just prior to parking. I looked and I didn't find the evap cannister. The car doesn't have the original engine, it is a 77 and now has a 72 engine with headers, intake, new carb etc. I will have to look around more to find the original hose that went to the cannister. Not sure otherwise..... Thanks

I ran the car for twenty minutes afterward without a leak....???

 

Hi Tim,
Your car originally had a vapor canister (it was part of the emissions control systems) but it's possible it's no longer there.
I still think it's odd for enough gasoline to be that far forward to leave 2 six inch puddles.
The only liquids that would normally be forward of the core support would be engine coolant and transmission fluid (on a auto car).
So??
Regards,
Alan

Vapor canister location… rear of driver's side apron.

 

I would guess it could be the 2 S hoses on the front passenger side they crack and leak under pressure, just my 2 cents

 

I agree with Blue
Try moving the return line around. How old are the fuel lines?

 

Hi,
I agree the 's' hoses can cause a leak but how does that leak migrate forward to appear on the ground under the headlight area?
Regards,
Alan

 

1000%. Overfilling your fuel tank is a BIG NO-NO....or can be....especially if it has a charcoal canister and the evap system.

Those that choose to do the overfilling and have no problems....it might be due to the vapor line is now plugged with varnished up gas and it is NOT working.

DUB

 

DUB,
How does the leaking gas get far enough forward that the puddles are on the ground under the headlights?
Regards,
Alan

 

How full is too full when filling up......?

Brian

 

Alan,

I honestly have NO CLUE. I wondered about that. and I am NOT disputing what the person wrote...but there is NO FUEL lines under the headlights. Unless there is a fuel cooler for some odd reason plumbed into the fuel system and there are hoses going in front of the A/C condenser...I have NO clue.

All I know is that if it was a fuel leak...it would just not 'self-correct' itself and stop leaking all on its own.

For what year model???? And do you have a vapor line????

DUB

 

Hi DUB,
Thank You!
That's why I kept asking the question…. no matter where or why the leak is occurring HOW does it make a puddle UNDER THE HEADLIGHTS unless the car is standing on it's nose!
There are only 2 liquids that far forward….coolant and transmission fluid.
Regards,
Alan

 

Mine is a 72 and I have no clue if it had or still has a vapor line....The OP I believe has a 77 and I know the motor is modified but he would have to answer the vapor line question.

Brian

 

Thanks for all the replies, not sure what it was, it hasn't done it again. I figure/hoped it had something to do with overfilling and I have a very steep driveway before I parked it. I will keep looking and thanks again for the info from everyone.

 

Hi Tim,
So the driveway is steep…. on the driveway, pulling into the garage, is the nose up or down?
How sure are you that the puddles were gas?
Regards,
Alan

 

Brian,

To tell if your car has a vapor line it is quite simple. You simply reach under your frame area on the drive side somewhere along your door opening area. You will fell the rear bake line on the inside edge at the bottom of the frame. IF there are TWO lines...then one of those is a vapor line. Simple as that. Takes me 5 seconds to tell or not.

****GENERAL COMMENT******
AND if a persons Corvette does have a vapor line and it is connected...then it is best to install the nozzle from the gas pump and fill it up to where the fuel is a few inches under the opening if your fuel tank is the large non-restrictor type. Even though there is a 'roll-over' switch or valve attached to the side of the fuel tank...it is still WISE not to fill the heck out of your gas tank.

If the fuel tank is set-up with the flapper and small hole for the nozzle...which will more than likely HAVE the vapor line and charcoal canister. Put it in and if you put it on constant fill....when it 'clicks'...STOP and take it out. You are done putting gas in the fuel tank. IF a person keeps adding and adding fuel to get more...then...do not be surprised if your vapor system starts to suck in fuel. And if a person actually 'thinks' that they are GAINING anything for over filling...they aren't. If anything they are doing damage. Because ..chances are...they are going to stop and re-fill when the fuel gauge gets down to about 1/4 of a tank if not a bit less anyway...UNLESS they are 'one of those' who tempt fate and try to drive on vapors and run the tank to almost dry....like they are in some type of competition and want to WIN because they got XXX miles on a tank of gas.

I hope your leak is no longer and issue.

Just wanting to mention this to all those who read this.

If a person has a fluid leak...really try to identify what liquid it actually is instead of taking a wild guess. The MAIN REASON is IF it is a FUEL LEAK....many of us on the Corvette Forum know how serious this is. AND all we want to do is make sure your car does not burst into flames. Generally leaks stay leaking....and just do not 'self correct' themselves. GOSH KNOWS...I sometimes WISH they did.

DUB