Gas fumes in truck & locking gas cap 1972 Chevy C10

[patroll]

My truck has a strong gas smell after I fill my gas tank on my 1972 Chevy C10, My gas tank has the EEC tubes on the passenger side going into my corner pillar , when you fill the gas tank it is strong and seems to fade away when tank is emptied , also replaced that gas tank hard to find a locking gas cap .

[71CHEVYSHORTBED402]

Seems somewhat common a full tank gives off fumes. I can't justify filling the tanks in my Chevys anyway. You might check or replace the rubber hoses, blow out your hard lines where possible, for at least the sake of maintenance.

A 72 gas cap won't fit on your new tank? If it does Napa has a cap for you. My 72 has a locking cap. The fumes are supposed to expand into the canister and out a vented gas cap. You can check the canister too, including the valves.

[truckster]

Also check those rubber lines. They're almost 50 years old, and they tend to crack and leak.

[lil hoodlum]

I top off my gas tank every 10 days. No gas fumes. Maybe the gasket under the lock ring on the gas tank is leaking of the hose from the filler neck?

[Kustomkampe]

Originally Posted by lil hoodlum

I top off my gas tank every 10 days. No gas fumes. Maybe the gasket under the lock ring on the gas tank is leaking of the hose from the filler neck?

Can anyone tell me is the 72 with eec gas tank will fit into a 71that has eec?
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[Kustomkampe]

Originally Posted by Kustomkampe

Can anyone tell me is the 72 gas tank with eec will fit into a 71that has eec?
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Posted via Mobile Device

[randy500]

Never had any gas fumes in any of my dozens of trucks over the past 35 years.
I would do this if i did.
Pressurize the tank....modify a gas cap to accept an air line fitting, regulate it to 5 psi or so and pressurize the tank.
Use a paint brush with leak detector and look for leaks at all seams and fittings.

[Steeveedee]

Originally Posted by Kustomkampe

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If they both had the EEC system, the tank will fit.

[Stocker]

Originally Posted by 71CHEVYSHORTBED402

A 72 gas cap won't fit on your new tank? If it does Napa has a cap for you. My 72 has a locking cap.

This. The rubber seal on the cap will rot and fail after several years. Gas will then leak out of a full or near-full tank, especially in right-hand corners.
Mine has only leaked out onto the outside of the tank at the cap, but you can easily smell it inside the cab.

[Richard]

Both of my 72"s had a gas smell at times. It was the rubber line from the fuel sender to the hard line near the gas tank. If the rubber fuel lines are original I would recommend replacing them.

[Richard]

Originally Posted by Steeveedee

If they both had the EEC system, the tank will fit.

Apologize for the high jack. Just wanted to say hello to a fellow Simi Valley 67-72 owner!

[Sheepdip]

My Oring seal at the sending unit flange was leaking, replaced it and no more smell from a full tank.

[68 P.O.S.]

^^^This! Sending unit gaskets are often the culprit.

[special-K]

On my '72 the gas cap has leaked right after a fill up if parked where the driver side sits lower even the slightest bit. Please don't judge me, but it's been that way over ten years. I still fill the truck until the nozzle pops off because it uses gas up so quick. It doesn't leak on turns. The only time it leaks is when I fill it up on my way home not so far away, or close to where I'm going, forget and park it with left side lower. Then I just turn it around. I'm used to it now and I like the Harley caliper emblem I stuck on it ages ago. Silly I guess, but I'm used to it now and act accordingly. I used to forget and sometimes it leaked till the next day. I'd move the truck, light the gravel on fire, and wash that area of the truck. Ever notice the bleached out woodgrain on the driver side cab corner trim of trucks? I replaced mine and the woodgrain survives now. I guess I should get a new cap and say screw the emblem. But I do get a lot of comments on it. More "Hey that's a cool gas cap" than "Hey I smell gas"

[Steeveedee]

Originally Posted by Richard

Apologize for the high jack. Just wanted to say hello to a fellow Simi Valley 67-72 owner!

right back!

[special-K]

His name is Steve, not Jack

[68 P.O.S.]

Originally Posted by special-K

His name is Steve, not Jack

[Steeveedee]

Originally Posted by special-K

His name is Steve, not Jack

Just don't yell that across the airport concourse!

[NewBayColony]

My 72 leaks out of the gas cap ,too. Last summer I filled it up just before I was away for a couple of days. Gas expanded, leaked down the side of the truck and bubbled the paint. Big stain on the driveway, too. Before that leak , I replaced the cap with 2 different brands of repops. Supposedly the correct caps for a 72 3/4 ton without smog equipment. Still leaked. I don't fill it up as much now but I would like to know if anyone has found a solution to this.

[Mike_The_Grad]

I use the Stant locking gas cap for 72 w/eec. I have also removed the smog/emissions stuff and just have my tank vented to atmosphere under the cab where the vapor return line would normally connect to the frame mounted vapor line. No issues with smell in around or under the cab. Eventually the rubber under the cap gets cracked and starts giving up the liquid gold down the side of the cab. So I replace it. I'm on cap number 5 in the last 6 years. The ethanol in today's gas is tough on rubber parts.

[External]

Looking for suggestions.
So far I have replaced all the lines, rubber and stainless.
The tank, the gasket on the tank. I siliconed the gasket also.
The only part of the lines I didn't replace was the vent lines inside the pillar.
Are those metal? If not that might be the culprit.
Oh and i am using the Stant locking vent cap for the 72 with EEC
I filled up the tank to almost full today and it's worse.
It's pretty dang bad. Bad enough i am already putting a price tag on how much i would pay for someone to fix it.
If anyone could help it would make me super happy.
Thanks for listening

[57taskforce]

The lines in the passenger side cab corner are steel. I’ve filled my truck up twice in the last week and a half with no issues with smell/leaks. I don’t have eec though.

[External]

I just pulled my locking Stant gas cap and its rubber was cracked pretty bad.
I put the original cap back on. Will see it that helps tomorrow.

[External]

Well, put the original gas cap back on. And smell is gone.
Thank you all for your posts

[scrapmetalart]

Originally Posted by Sheepdip

My Oring seal at the sending unit flange was leaking, replaced it and no more smell from a full tank.

this is the first place id check. i just replaced mine and cleaned some rust scale off the tank where the o ring sits. much better now