Fuel tank vent - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Nolowrider · 01-15-2006, 12:28 PM

After replacing by stock mech fuel pump with a $65.00 Holley mech my problem still exist. Truck idles fine when accelerating it wants to bog down, like it is running out of gas. I noticed that my fuel filter is not full like it used to be. Being that the fuel pump is good and I don't think it is a vapor lock issue, I then turned my attention to the tanl. If I leave my gas cap open I think it runs fine, but when I lock it closed it wants to die after a few minutes. Pop the cap and is fine. So, I think my tank is not venting. My truck has never had a return line since I had it, no carbon canister. Where is the tank vent? Any suggestions on how to fix this problem? The cap has been on this truck for 20 yrs it is off a Dodge Charger (if I rememer right).

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us111 · 01-15-2006, 01:13 PM

hello,,the vent on my 76 stepside is right in top of the sending unit,it has 3 lines in it,delivery,return (if you need it) and vent..the vent is just a little short hose with one of those plastic breather caps on it that "could" be stuck closed..

**swervin ervin** · 01-15-2006, 02:51 PM

When I removed my charcoal canister and changed the fuel pump, I made a vent on my tank. I just used a short piece of hose with a small filter on the charcoal canister vent line at the tank switching valve. Works like a charm. Of course I redone all the fuel lines going to the tank. I didn't want the hard lines left laying in the cradle below the radiator.

If you never had a charcoal canister stock, it would be vented just like us111 stated.

Nolowrider · 01-15-2006, 04:13 PM

After looking at mine, I only have two lines on the sending unit. Feed and return. The return is capped off next to the radiator. On the tanl itself next to the filler hose there is another line that goes to the top of the filler close to the cap on the inside of the fender. Is that the vent? I though that was a line to keep you from over filling it. Can I just "T" into that and make a vent?

79BIG10 · 01-15-2006, 08:54 PM

Yes you should be able to do that.

f.monroe · 01-15-2006, 11:16 PM

Sounds like a venting problem but I had a similar problem with a 77 in high school . Mine turned out to be dry rotted fuel lines from the tank to the hard lines . It was also hard to start after sitting for a few days . Just a thought . Frank

01-15-2006, 12:28 PM	#1
Nolowrider Senior Member Join Date: Jan 2005 Location: New Orleans Posts: 1,365	Fuel tank vent After replacing by stock mech fuel pump with a $65.00 Holley mech my problem still exist. Truck idles fine when accelerating it wants to bog down, like it is running out of gas. I noticed that my fuel filter is not full like it used to be. Being that the fuel pump is good and I don't think it is a vapor lock issue, I then turned my attention to the tanl. If I leave my gas cap open I think it runs fine, but when I lock it closed it wants to die after a few minutes. Pop the cap and is fine. So, I think my tank is not venting. My truck has never had a return line since I had it, no carbon canister. Where is the tank vent? Any suggestions on how to fix this problem? The cap has been on this truck for 20 yrs it is off a Dodge Charger (if I rememer right). [IMG] [IMG][/IMG] Last edited by Nolowrider; 01-15-2006 at 12:45 PM.

01-15-2006, 01:13 PM	#2
us111 Registered User Join Date: Jul 2004 Location: ashland oh Posts: 660	Re: Fuel tank vent hello,,the vent on my 76 stepside is right in top of the sending unit,it has 3 lines in it,delivery,return (if you need it) and vent..the vent is just a little short hose with one of those plastic breather caps on it that "could" be stuck closed..

01-15-2006, 02:51 PM	#3
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Re: Fuel tank vent When I removed my charcoal canister and changed the fuel pump, I made a vent on my tank. I just used a short piece of hose with a small filter on the charcoal canister vent line at the tank switching valve. Works like a charm. Of course I redone all the fuel lines going to the tank. I didn't want the hard lines left laying in the cradle below the radiator. If you never had a charcoal canister stock, it would be vented just like us111 stated. __________________ Mike 1985 Chevy C-10

01-15-2006, 04:13 PM	#4
Nolowrider Senior Member Join Date: Jan 2005 Location: New Orleans Posts: 1,365	Re: Fuel tank vent After looking at mine, I only have two lines on the sending unit. Feed and return. The return is capped off next to the radiator. On the tanl itself next to the filler hose there is another line that goes to the top of the filler close to the cap on the inside of the fender. Is that the vent? I though that was a line to keep you from over filling it. Can I just "T" into that and make a vent?

01-15-2006, 08:54 PM	#5
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,774	Re: Fuel tank vent Yes you should be able to do that. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

01-15-2006, 11:16 PM	#6
f.monroe Senior Member Join Date: May 2004 Location: Caldwell,Tx. Posts: 3,648	Re: Fuel tank vent Sounds like a venting problem but I had a similar problem with a 77 in high school . Mine turned out to be dry rotted fuel lines from the tank to the hard lines . It was also hard to start after sitting for a few days . Just a thought . Frank __________________ Born and proudly residing in a Red State !

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