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

eedgell · 12-21-2007, 12:03 PM

My '71 has gas smell in the cab, so I started investigating the vent lines, and discovered that the vent line from my tank is being used as a return line from the fuel pump. Is this right? If not is there a return line to the tank on '71-'72 with eec? What is the best way to vent the tank? Vented fuel cap or no?

Sweet72 · 12-21-2007, 02:27 PM

Replace all the small hoses since they tend to dry rot quickly and will stink up the cab. Don't forget the short section near the filler neck just inside the cab!

I'm surprised no-one has advised you to relocate that Molotov Cocktail to the rear of the truck!

eedgell · 12-21-2007, 05:10 PM

Thanks for the input. What I really want to know is, do these trucks have a return line or not? I am thinking that they have a feed, and vent. No return.

Olden Days · 12-22-2007, 06:48 AM

71 and 72 = return line and non vented cap

eedgell · 12-23-2007, 10:44 AM

Quote:

Originally Posted by Olden Days

71 and 72 = return line and non vented cap

If so, how does the tank vent?

Olden Days · 12-23-2007, 01:02 PM

I dont know exactly how it all routes together but the charcoal canister has something to do with it. Since my 72 is exempt from smog checks, I got rid of all that charcoal can and return line stuff. and just set mine up like the earlier ones with vented cap

12-21-2007, 12:03 PM	#1
eedgell It's the air up here Join Date: Mar 2007 Location: Western Colorado Posts: 710	Fuel tank vent problems My '71 has gas smell in the cab, so I started investigating the vent lines, and discovered that the vent line from my tank is being used as a return line from the fuel pump. Is this right? If not is there a return line to the tank on '71-'72 with eec? What is the best way to vent the tank? Vented fuel cap or no? __________________ 1971 cheyenne k10 4 speed np 205 454 BB factory a/c Never drink down stream of the herd! Eric

12-21-2007, 02:27 PM	#2
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	Re: Fuel tank vent problems Replace all the small hoses since they tend to dry rot quickly and will stink up the cab. Don't forget the short section near the filler neck just inside the cab! I'm surprised no-one has advised you to relocate that Molotov Cocktail to the rear of the truck! __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction.

12-21-2007, 05:10 PM	#3
eedgell It's the air up here Join Date: Mar 2007 Location: Western Colorado Posts: 710	Re: Fuel tank vent problems Thanks for the input. What I really want to know is, do these trucks have a return line or not? I am thinking that they have a feed, and vent. No return. __________________ 1971 cheyenne k10 4 speed np 205 454 BB factory a/c Never drink down stream of the herd! Eric

12-22-2007, 06:48 AM	#4
Olden Days Living In The Past Join Date: Nov 2003 Location: Rockies Posts: 709	Re: Fuel tank vent problems 71 and 72 = return line and non vented cap

12-23-2007, 01:02 PM	#6
Olden Days Living In The Past Join Date: Nov 2003 Location: Rockies Posts: 709	Re: Fuel tank vent problems I dont know exactly how it all routes together but the charcoal canister has something to do with it. Since my 72 is exempt from smog checks, I got rid of all that charcoal can and return line stuff. and just set mine up like the earlier ones with vented cap



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