Return line or no return line???

[1972BackInBlackC10]

Is a return line really needed? I installed a fuel pump with only a feed line and no return on my 454 but my aftermarket fuel tank i bought has the outlet for it.

Should i buy a fuel pump with a return line or should i run what i have and cap off the oulet on my tank? thoughts and opinions would be appreciated

[Steeveedee]

If you aren't experiencing vapor lock issues, just cap the return line connection at the tank.

[1972BackInBlackC10]

I havent ran the engine yet im in the process of building the truck so i couldnt say if it has vapor lock issues

[RustyPile]

Originally Posted by 1972BackInBlackC10

I havent ran the engine yet im in the process of building the truck so i couldnt say if it has vapor lock issues

Correct, there is no way at this stage of the build to predict whether or not you will encounter vapor lock. If you delete the return and experience a vapor lock condition, it will leave you stranded on the side of the road, not sitting in your driveway. It's much better to have something and not need it than to need it and not have it..

Fuel returns on carburetor systems is just about the best improvement GM designed.. Shortly after I bought my truck, I discovered some PO had removed the fuel return line. Shortly thereafter, I changed the pump and installed a line back to the tank.

The tank you bought, is it designed to fit behind the seat? The factory didn't make provisions for a return line on the actual tank. The return line goes in the fuel gauge sending unit right beside the fuel pick up line. Don't mistake the fuel vapor system connector for a return line connection. This connection is located in the tank's upper corner on the passenger side. This connection is connected to a steel line that runs up the PS B pillar, back down and winds up at vapor cannister under the battery...

[jumpsoffrock]

Originally Posted by RustyPile

Correct, there is no way at this stage of the build to predict whether or not you will encounter vapor lock. If you delete the return and experience a vapor lock condition, it will leave you stranded on the side of the road, not sitting in your driveway. It's much better to have something and not need it than to need it and not have it..\

In addition to this point, It will also be easier to add the return line now that the truck is still a project.

I guarantee 3 months after your truck is FINALLY finished--all that money and hard work and waiting--and it leaves you in a parking lot embarrassingly cranking your engine for 35 seconds every time you turn it off, the last thing you're gonna wanna do is tear your brand new finished truck back apart to install more stuff

[Steeveedee]

After seeing RustyPile's post, and seeing that you have a 454 (based on your handle), you may need the return line. Millions of vehicles did without them, but many suffered from vapor lock. The newer stuff seems to be more likely to need the return line.

[1972BackInBlackC10]

Originally Posted by RustyPile

Correct, there is no way at this stage of the build to predict whether or not you will encounter vapor lock. If you delete the return and experience a vapor lock condition, it will leave you stranded on the side of the road, not sitting in your driveway. It's much better to have something and not need it than to need it and not have it..

Fuel returns on carburetor systems is just about the best improvement GM designed.. Shortly after I bought my truck, I discovered some PO had removed the fuel return line. Shortly thereafter, I changed the pump and installed a line back to the tank.

The tank you bought, is it designed to fit behind the seat? The factory didn't make provisions for a return line on the actual tank. The return line goes in the fuel gauge sending unit right beside the fuel pick up line. Don't mistake the fuel vapor system connector for a return line connection. This connection is located in the tank's upper corner on the passenger side. This connection is connected to a steel line that runs up the PS B pillar, back down and winds up at vapor cannister under the battery...

No the fuel tank is a rear frame mounted tank

[1972BackInBlackC10]

return line it is! lol looks like ill be getting a new fuel pump, thanks for the responses guys

[LS short box]

Just a question.
If you run a return line do you install an adjustable fuel pressure regulator with a return port?

[71CHEVYSHORTBED402]

Return lines weren't installed until 72, though I suppose late model 71 might have them. Might depend on transmission. There's a rumor they're "required" for A/C trucks, and vendors got that one wrong for upper fuel tubes from the pump. Judging by the parts book the transmission was a factor, not A/C. In 1972 they call out for one with a 400TH, for example.

I just "finished" rebuilding a 71 402/400TH with A/C to factory, short an HEI was installed, and no TCS, or anti-dieseling. No return line in other terms, everything is real happy. Perhaps that might change when it's hot, the truck runs surprisingly cool. Some declare "vapor-lock" is possible w/o a return.

[Steeveedee]

^I'm set up like your truck with my '70. It vapor locked in some intense heat once, but that was because of cooling system issues. That has since been addressed.

[RustyPile]

Originally Posted by LS short box

Just a question.
If you run a return line do you install an adjustable fuel pressure regulator with a return port?

The return line in and of itself does not require a pressure regulator. Inside the return nipple at the pump is an orifice that allows only a certain amount of fuel to pass through. The pump is designed to maintain a specified fuel pressure while at the same time, returning some of the fuel.

Some carburetors require a lower than normal fuel pressure to prevent flooding.. A pressure regulator may be required in that situation.