Gasoline smell in cab

[70ChevyCST]

Hi guys,
I already did a search on this topic here and read "Fuel Smell in Cab" by spdrcr29 in March of 07. There seems to be no consensus here...about half said it's normal because the gas tank is right behind the seat and the other half said check the sending unit gasket, vent connections, filler cap etc. Well I have a newly frame off restored 70 CST-10 fleetside longbox and the seller left several bugs for me to swat. The next bug for me to squish is this gas smell problem. I do not want to move the tank. I've inspected behind the seat carefully and have seen no signs of seepage...There's a new tank, sending unit and cap. There is no vent on this tank which surprises me! I'm thinking there's a new sending unit gasket if there's all these new parts here....but I will obviously check this now...But here's my question: In the LMC parts catalog I see a cardboard tank cover and a tank cover carpet are available. Could this be why I'm still smelling gas? The restorer did not spring for either of these items. Also: The tank is still bare metal. Should it be painted? Oh yes...smell is worse when tank is full. Thanks everyone in advance....
Bob

[69rut]

Isn't there a joint between the filler neck and the tank?

I don't think carpet will help. If you have this smell now, think how much worse it could be once the carpet absorbs the oder.

[mrein3]

You probably have a 1972 cap on a 1970 tank. Or vice versa. In 1972 they went to a vented system. Before that the vent is the cap.

Try a new cap.

[sodak69c10]

try a new gas cap, you said that the tank isn't vented, if you have a non vented cap the heat in the cab on a hot day could cause the gas to expand an start to seep out where ever it can, might be a good idea to check and the pinch weld around the tank for moisture

one way to check is on a hot day after it sits go crack the gas cap and listen for a loud hiss from excessive pressure, if there is pressure in the tank it might help you locate a leak to because it would open up the hole

on kind of the same note of vented caps, in the summer time i don't fill my tank over 7/8 full because if it sits the heat makes it expand and run out my gas cap vent, i found out the hard way my cap wasn't venting it broke the welds that hold the pick-up tube in the sender and when the tank was full it leaked , i found the leak sanded paint/dirt out of the area leaking and filled the hole around the tube with jb weld and then got a vented cap that was a year ago and no smell anymore

[72freak]

i didnt read everything.........but.....here are a few.........

vented cap, cracked gasket between tank neck and cab hole, sending unit o ring or a pin hole in the tank.

[riche]

And last but not least... If you put any pressure on the fuel line exiting the sending unit. It can make a small hair-line crack around the hose. It will leak a little though when the tank is full. Not enough to fill up the cab with gas. But enough for you to see.

[jgrh64]

I've got the same problem on my '70 haven't solved it yet - put about 1 PSI pressure into it to see if it would hiss but nothing found. My old '66 and '64 had tank in cab and no gas smell , it is really worysome smeling gas inside what happens if there is a static spark ?