I smell GAS!!

[Lated]

I just replaced the in cab fuel tank on my 70. Now I smell gas sometimes when I first get in the truck. It's only in the afternoon on warm days after it's been sitting in the sun all day, never in the morning when it's cooler. I pulled the seat out yesterday and checked for leaks but couldn't find any. This coupled with only smelling fuel in the afternoons leads me to believe that the tank just isn't vented properly. Is there anyway to vent the tank or do I just need to buy a new gas cap?

[Orange]

Just a note, I smell gas too.
My tank is the 1971 version, but it presents the same exact problems you describe.

My guess it is something to do with gas being shut up in a cab all day in the hot sun. The vapors are just going to present. I have never really noticed it before, but I never DD it before either this much in the hot months.

DLB

[lbpd719]

here's a question (and kind of how I fixed my version of the same problem. How are all of your filler neck seals, including your cap. Do you get a large inrush of air when you remove your cap, and is your cab to filler neck seal in good shape.

When I first got my truck, I went through the same hunt. after sealing up the rubber on the cab and changing the cap, problem was pretty much solved. I can still smell a little fuel on occasion, but not like I could before..

Good Luck

[Lated]

When I replaced the tank I replaced everything up to the fuel pump, sending unit and grommet, fuel line, filler neck grommet and the filler cap all because the tank was naaasty! I had to clean the fuel filter at the carb once a week so the engine could get enough fuel to run. I didn't smell gas before the tank swap but that could be because there were two 1/8 inch holes drilled in the filler neck outside the cab either to vent the tank or because there was a chain at one point attached to the cap so it wasn't forgotten. The new cap is locking but I haven't pulled the cap off when I could smell gas in the truck. I'll pull it off tomorrow afternoon and see what happens.

[67_C20Pres]

Same problem with my 67'. When I replaced my seat I noticed a port @ the passenger side on the top of the tank. Looks like a return line or vapor recovery port. But mine is just kind of capped off. I'll need to dig more on the fuel setup.

Suggestions for the other posts are: Check the fuel sender O-ring & fuel pump connection for leaks. My has a short section of rubber fuel line between the sender and the line and it was leaking. That helped some but the vent, in my case, is probably the key. As vapor pressure increases due to heat, it has to go somewhere and I suspect that there was a recovery setup at one time. Or it's the wrong damn tank.

[mrein3]

I believe in 1972 GM went to a non-vented cap. Your locking cap may be that style. I don't want to be responsible for somebody stealing your gas but you may want to try a stock cap.

If it is not vented, and it heats up in the sun, those fumes have to go some where.

[sick69]

On the passenger side of the tank on the top there is a vent tube,,,,where does it vent to? seems like it just vents into the cab.

Frank

[67_C20Pres]

Originally Posted by sick69

On the passenger side of the tank on the top there is a vent tube,,,,where does it vent to? seems like it just vents into the cab.

Frank

Yeah, another fine cobble job by the previous owner. It's topped off with a yellow wire nut and electrical tape. Positive seal, I think not! HEHE

[sick69]

Well there is a good place to start for removing the fuel smell lol

[Lated]

I don't have a vent on the passanger side. It's gotta be the cap not venting.

[whitelightenin69]

had the same problem on my 69 when I changed to a locking cap, I just cut a small hole in the rubber seal on the cap, problem solved.

[dan42]

Sometimes I smell gas too - even though my tank is under the bed. Usually after I've eaten something foul.

[GREASEMONKEY72]

i smell it to now and the vent tube doesnt go anywhere exept up the cab corner and back down, its not a po job its how it came, and ive got the stock non locking cap and no leaks anywhere and really the only times i smell gas are when i get back in after pumping some in at the station and on hot days other than that i hardly ever smell it

[GREASEMONKEY72]

Originally Posted by dan42

Sometimes I smell gas too - even though my tank is under the bed. Usually after I've eaten something foul.

[EAST SIDE LOW LIFE]

I had this problem with my 50'. I had to change the fuel sending unit and decided to splurge and bought a new tank to sender seal, this solved the problem.

esll.

The lower the fuel the more fuel vapours are present and tends to smell stronger.