Pulling the rear tank, can't figure out the return for front tank!?! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Woodward · 08-10-2007, 12:08 PM

Since all of the fuel lines were rotted and leaking, I decided to pull all of the rear tank lines, and just run the front tank for time being. I have the feed line ran, but wasn't sure about the vent and return. Does the vent need to run to the cansiter up front next to the battery? And it looks like there isn't a vent or return line coming out of the front tank. These both run into the ball valve that switches between tanks. I can take a couple pictures if it would help. Also, I wasn't sure if there is a diagram for the fuel tank and lines.. It would help! It's a 72 C10. Thanks alot gents! -Woodward

Woodward · 08-11-2007, 01:20 PM

Anyone running just the front fuel tank? There's gotta be someone out there!

Lugnutt · 08-11-2007, 04:46 PM

I have a 72 K10 to which I added a rear fuel tank years ago. The original front tank (behind the seat) has a normal fuel line that connects to the engine fuel pump and a vent line that connects to an Evaporator Control Canister next to the battery. When I installed my rear tank, I ran both tank's fuel lines through an electric fuel switch and I tied the rear tank vent line into the front tank vent line so they both vent to the canister.

Now the front (cab) tank vent does a loop from the top of the tank, up into a cavity in the corner of the cab behind the passenger's window almost to the top of the cab and then loops down and out again on it's way to the canister. I've got pictures from the original Chevrolet Service Manual to show the route it takes. I have more pages but I think these should be able to show you what you need to know about the vent.

Good luck

Lugnutt · 08-11-2007, 04:51 PM

Sorry, my scanned pages didn't show up on my Post Reply. I musta did something wrong importing them. I hope the text helps.

Woodward · 08-12-2007, 03:54 PM

Thanks alot for your help! I think that I'll need to drop that front tank to see what's coming out of it.. Like you said, it may be vented already up out the top. If so, I'll need to just focus on the return.. So once I have the tank dropped and IF there isn't a return, I'll add it. Someone told me they make a fitting that you can add after drilling a hole, and once it's installed the 3/8 line can't pull out of it. Yourself or anyone know what they call that fitting? Or anyone that has added a line to a tank, please let me know what worked for you. Thanks in advance!!

Lugnutt · 08-13-2007, 03:57 PM

Wow, be careful drilling holes into a gas tank!

Do some research first; I think (but don't take this to the bank) that your supposed to fill the tank full with water before doing anything that could cause a spark. An empty gas tank is a potential bomb.

Please be careful

08-10-2007, 12:08 PM	#1
Woodward Registered User Join Date: May 2006 Location: Federal Way Wa Posts: 6	Pulling the rear tank, can't figure out the return for front tank!?! Since all of the fuel lines were rotted and leaking, I decided to pull all of the rear tank lines, and just run the front tank for time being. I have the feed line ran, but wasn't sure about the vent and return. Does the vent need to run to the cansiter up front next to the battery? And it looks like there isn't a vent or return line coming out of the front tank. These both run into the ball valve that switches between tanks. I can take a couple pictures if it would help. Also, I wasn't sure if there is a diagram for the fuel tank and lines.. It would help! It's a 72 C10. Thanks alot gents! -Woodward Last edited by Woodward; 08-10-2007 at 12:09 PM.

08-11-2007, 01:20 PM	#2
Woodward Registered User Join Date: May 2006 Location: Federal Way Wa Posts: 6	Re: Pulling the rear tank, can't figure out the return for front tank!?! Anyone running just the front fuel tank? There's gotta be someone out there!

08-11-2007, 04:46 PM	#3
Lugnutt Registered User Join Date: Jan 2007 Location: San Jose, California Posts: 194	Re: Pulling the rear tank, can't figure out the return for front tank!?! I have a 72 K10 to which I added a rear fuel tank years ago. The original front tank (behind the seat) has a normal fuel line that connects to the engine fuel pump and a vent line that connects to an Evaporator Control Canister next to the battery. When I installed my rear tank, I ran both tank's fuel lines through an electric fuel switch and I tied the rear tank vent line into the front tank vent line so they both vent to the canister. Now the front (cab) tank vent does a loop from the top of the tank, up into a cavity in the corner of the cab behind the passenger's window almost to the top of the cab and then loops down and out again on it's way to the canister. I've got pictures from the original Chevrolet Service Manual to show the route it takes. I have more pages but I think these should be able to show you what you need to know about the vent. Good luck

08-11-2007, 04:51 PM	#4
Lugnutt Registered User Join Date: Jan 2007 Location: San Jose, California Posts: 194	Re: Pulling the rear tank, can't figure out the return for front tank!?! Sorry, my scanned pages didn't show up on my Post Reply. I musta did something wrong importing them. I hope the text helps.

08-12-2007, 03:54 PM	#5
Woodward Registered User Join Date: May 2006 Location: Federal Way Wa Posts: 6	Re: Pulling the rear tank, can't figure out the return for front tank!?! Thanks alot for your help! I think that I'll need to drop that front tank to see what's coming out of it.. Like you said, it may be vented already up out the top. If so, I'll need to just focus on the return.. So once I have the tank dropped and IF there isn't a return, I'll add it. Someone told me they make a fitting that you can add after drilling a hole, and once it's installed the 3/8 line can't pull out of it. Yourself or anyone know what they call that fitting? Or anyone that has added a line to a tank, please let me know what worked for you. Thanks in advance!!

08-13-2007, 03:57 PM	#6
Lugnutt Registered User Join Date: Jan 2007 Location: San Jose, California Posts: 194	Re: Pulling the rear tank, can't figure out the return for front tank!?! Wow, be careful drilling holes into a gas tank! Do some research first; I think (but don't take this to the bank) that your supposed to fill the tank full with water before doing anything that could cause a spark. An empty gas tank is a potential bomb. Please be careful



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