fuel line return question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

franko72 · 05-24-2004, 06:53 PM

I bought my truck with the return line from the fuel pump plugged at the pump .It is also plugged off just below the gas tank.It it a 402 BB with a quadrajet, should I reconnect the return line from the pump to the tank.Are there any performance problems that could develope? What is the purpose of the return line anyway.could this be the reason why my truck doesnt come out of the hole strong?

68speedalert · 05-25-2004, 11:17 PM

The return line is to return fuel back to the tank..................duh. Just kidding. Your carb only uses a small amount of the fuel the pump puts out under normal driving. What can happen without the return is the fuel sitting in the line waiting to go to the carb can boil in the hose and cause a vapor lock. The return line lets the fuel circulate and hopefully not boil.

No, the line disconnected has no bearing on your hole-shot. if your truck jumps and then sags or cuts out, it could be the fuel pump. Look closer to base timing, mechanical advance, four barrels opening up. Maybe find what your rear-end gear ratio is. If it's something like 3.08s, there is the problem.

franko72 · 05-26-2004, 04:55 PM

the rear end ratio and type is a dana 70 3:54 , it has a 10 5/8" ring gear.Do you think that this is why it doesnt do a good hole shot?

*Cruiser71* · 05-26-2004, 07:41 PM

I have found that all the 1/2 tons I owned had return lines and my 3/4's didn't. I think it may have to do with emissions. i could be wrong.

68speedalert · 05-26-2004, 07:43 PM

I'm certainly not an expert on rear dif questions. you probably have a large tire as well since this is obviously a 3/4 ton. All this coupled with a probable th400 auto trans could be it. I'm not sure but I don't think those tranny's have a low first gear.

A gear like a 3.73 or 4.11's do make a big difference.

Did you try manually putting the shifter in 1st to see if there is any difference?

franko72 · 05-26-2004, 08:57 PM

yes it is a 3/4 ton with a 400 turbo trans.I also have 16.5 " tires. I can pull it down in 1st gear when I have a little momentum and it will bark the tires, just not from a complete standstill

05-24-2004, 06:53 PM	#1
franko72 Franko72 Join Date: May 2004 Location: Cincinnati,Ohio Posts: 471	fuel line return question I bought my truck with the return line from the fuel pump plugged at the pump .It is also plugged off just below the gas tank.It it a 402 BB with a quadrajet, should I reconnect the return line from the pump to the tank.Are there any performance problems that could develope? What is the purpose of the return line anyway.could this be the reason why my truck doesnt come out of the hole strong?

05-25-2004, 11:17 PM	#2
68speedalert Semi-Senior Member Join Date: Feb 2003 Location: Washington, MO Posts: 390	The return line is to return fuel back to the tank..................duh. Just kidding. Your carb only uses a small amount of the fuel the pump puts out under normal driving. What can happen without the return is the fuel sitting in the line waiting to go to the carb can boil in the hose and cause a vapor lock. The return line lets the fuel circulate and hopefully not boil. No, the line disconnected has no bearing on your hole-shot. if your truck jumps and then sags or cuts out, it could be the fuel pump. Look closer to base timing, mechanical advance, four barrels opening up. Maybe find what your rear-end gear ratio is. If it's something like 3.08s, there is the problem. __________________ '68 50th Anniversery LWB Custom Fleetside, '77 305 v-8, turbo 350, factory speed alert (still works), '71 drivetrain w/front discs. Some call it ugly yellow, others call it Ochre '83 Jeep CJ-7, <80,000 miles, original owner '04 Chevy Suburban, 4x4, 2500, 6.0 ltr, Predator Diablo programmer '95 GMC K1500 Extended cab

05-26-2004, 07:43 PM	#5
68speedalert Semi-Senior Member Join Date: Feb 2003 Location: Washington, MO Posts: 390	I'm certainly not an expert on rear dif questions. you probably have a large tire as well since this is obviously a 3/4 ton. All this coupled with a probable th400 auto trans could be it. I'm not sure but I don't think those tranny's have a low first gear. A gear like a 3.73 or 4.11's do make a big difference. Did you try manually putting the shifter in 1st to see if there is any difference? __________________ '68 50th Anniversery LWB Custom Fleetside, '77 305 v-8, turbo 350, factory speed alert (still works), '71 drivetrain w/front discs. Some call it ugly yellow, others call it Ochre '83 Jeep CJ-7, <80,000 miles, original owner '04 Chevy Suburban, 4x4, 2500, 6.0 ltr, Predator Diablo programmer '95 GMC K1500 Extended cab

05-26-2004, 08:57 PM	#6
franko72 Franko72 Join Date: May 2004 Location: Cincinnati,Ohio Posts: 471	yes it is a 3/4 ton with a 400 turbo trans.I also have 16.5 " tires. I can pull it down in 1st gear when I have a little momentum and it will bark the tires, just not from a complete standstill Last edited by franko72; 05-26-2004 at 09:01 PM.

05-26-2004, 04:55 PM	#3
franko72 Franko72 Join Date: May 2004 Location: Cincinnati,Ohio Posts: 471	the rear end ratio and type is a dana 70 3:54 , it has a 10 5/8" ring gear.Do you think that this is why it doesnt do a good hole shot?

05-26-2004, 07:41 PM	#4
Cruiser71 AKA Phillip Johnson, AKA BANNED Join Date: Feb 2004 Location: Northern Calif. Posts: 193	I have found that all the 1/2 tons I owned had return lines and my 3/4's didn't. I think it may have to do with emissions. i could be wrong.



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