Thread: Gas Tank Vent Line

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73 Nova had char-coal canister , vent line from gas tank went into. took off canister left line open hanging by drivers door. Smell of fumes on hot day were rough. What correcet way on what to do with this line. Can just let hang off gas tank or cap it drill gas cap.

plug them all you need to do is vent the cap

Thanks Pat , Thats what I thought but wanted make sure.

Any "but be sure you ....." things with drilling the cap? I've got a similar situation using a Blazer tank.

Like Pat says but I would also advise;

1) Make sure vent is adequate for fuel draw. Otherwise you will create a vacuum and will be forever chasing a fuel starvation problem.

2) It's best that the vent does not aloow fuel to spill out freely in the unfortunate case that your car is upside down for any reason, leading to you burning alive 'till your dead.

Kitz

yes buy a vented cap

Venting the cap would work just fine on many vehicles.

But on my 32 high boy the cap "is about level" with the fuel level in the tank when it's full so the fuel is on the verge of running out of the tank if you park on an incline. Not the best seniero to vent the cap.

So what I did was vent the tank to a 5/16" steel line that I bent and routed up through the trunk floor, straight up to the top of the trunk (inside), bent it back 180 degrees and routed back down through the trunk floor and then routed it forward to the inside of the frame rail. Then I drilled the frame and taped it for 1/8" NPT. I used a 1/8" NPT FORD inline carb fuel filter screwed into the frame and attached the hose end to the 5/16" steel line with a short piece of fuel line and two clamps.

Incoming air, is vented/filtered by the fuel filter, then the height of the steel tubing keeps the fuel from sloshing out. No fuel smell is inside the car because it's vented to the outside, even though it's plumbed inside. It does not have a one way flow valve, but when and if I need that I will have BIGGER problems to deal with! Tested for 8800 miles so far.

Originally Posted by cookster

73 Nova had char-coal canister , vent line from gas tank went into. took off canister left line open hanging by drivers door. Smell of fumes on hot day were rough. What correcet way on what to do with this line. Can just let hang off gas tank or cap it drill gas cap.

I would get another charcoal canister from a junker or junk yard ....You will still smell fumes with a vented cap ,get fuel slosh,plus ,if it is a full system ,the engine will clear the canister when running,resulting in better gas mileage ,albeit a slim amount,plus it will not be a stinker............

Originally Posted by shawnlee28

I would get another charcoal canister from a junker or junk yard ....You will still smell fumes with a vented cap ,get fuel slosh,plus ,if it is a full system ,the engine will clear the canister when running,resulting in better gas mileage ,albeit a slim amount,plus it will not be a stinker............

no you will not smell gas less you are sitting on top of the gas cap when driving down the road come on shawnlee he can run a one way valve on the end a loop of steel tub hirer then the the tank it self vent thru the filler neck like said if he wants to put a one way valve on the end of the loop must be out side fo the tunk can be a pcv valve .he ask if he could plug it yes he can. now should you go find a other one thats is up to him

I'm glad this subject came up. We (my boy and I) restored an '80 Volare Duster a few years back which he still owns and drives. We have a problem regarding gas tank venting but it is the opposite of the one mentioned in this thread.

Instead of pulling a vacuum in the tank as Kitz mentions, his builds up pressure in the tank. Sometimes after driving for an extended length of time then stopping for gas there is so much pressure it almost blows the filler cap out of his hand (his description). When the fuel level is low and there is pressure in the tank he gets goofy gauge readings, like, it shows to be lower on gas than it really is. Could the pressure be pushing the float down into the gasoline and causing that?

The Volares and Aspens of that era ('76-'80) have a big fancy chrome filler cap instead of having a filler access door. I drilled a small hole through the cap so it could breathe, and that didn't help the appearance of the cap and didn't impress the safety inspection guy one bit. Instead of taking the trouble to solve the problem, I took the lazy way out and bought another cap for him to put on before he takes the car in for inspection.

What do I do now, coach?


Jim

Vent it under the car ! ( one of the Coach's )

Here are some tip-over vents . For a Fuel cell . Maybe that Tech guy can tell us what we need so we can go down the track ?

[QUOTE=DennyW] On the gas tank itself, there should be a relief check valve, which allows fumes to be stored in the Charcoal canister, when the fuel, or pressure expands in the tank. Maybe it is not working properly, or a line is pinched shut, or the check valve at the canister is not working."


Thanks for the input, guys.

And Denny, the next time the boy drives the car over to my place I'll try to maneuver my creaky old carcass underneath and see what I can see.

Jim

Originally Posted by pat mccarthy

no you will not smell gas less you are sitting on top of the gas cap when driving down the road come on shawnlee

I have seen some wild customs ...never know...

Unless he has a 40 acre driveway ,you will smell gas,I meant to say that the vented cap will make pressure resulting in venting out the line that does not go to the charcoal canister,because like mentioned the cap is a one way vent ,meaning the pressure has to go somewhere........it goes out the line that has no charcoal canister ,therefore it becomes the stinker .........but the vented cap will leak soon enuff.......
My 66 had the vented cap system,its real funny when guys use a non vented cap on these ,The tank has no vents at all... meaning the cap has to vent both ways,most caps only allow air in, when a good hot day came along ,tank inside of cab,the rubber fuel lines under the hood would swell up like a bloated radiator hose.....

Originally Posted by shawnlee28

I have seen some wild customs ...never know...

Unless he has a 40 acre driveway ,you will smell gas,I meant to say that the vented cap will make pressure resulting in venting out the line that does not go to the charcoal canister,because like mentioned the cap is a one way vent ,meaning the pressure has to go somewhere........it goes out the line that has no charcoal canister ,therefore it becomes the stinker .........but the vented cap will leak soon enuff.......
My 66 had the vented cap system,its real funny when guys use a non vented cap on these ,The tank has no vents at all... meaning the cap has to vent both ways,most caps only allow air in, when a good hot day came along ,tank inside of cab,the rubber fuel lines under the hood would swell up like a bloated radiator hose.....

i have welded cab corner in them old chevys trucks and other parts my hart rate allways pick up a bit we put wet rag around the fill cap