Stock return line for electric pump: good idea?

[Dippy Daddy]

Hey Folks,

I want to go with an electric fuel pump in my gas tank (Walbro TBI pump with reservoir tray that puts out 12 psi) and while I was thinking about how to install a return line from the regulator back to the tank, it occurred to me that there's already one there from the factory. The stock fuel filter ties into it, up front by the mechanical fuel pump. The return line looks like it's 5/16-inch, like the fuel line, so I'd like to use the return line for my new setup.

Have any of you done this? Or do you know any reasons it won't work? I want to use the stock fuel line from the tank forward, with a Quick Fuel Technology 30-9000QFT return regulator to get me down to 5 psi for a happy carb. Otherwise the car's a bone stock '86 Fifth Avenue and it runs pretty well. To delete the LeanBurn I rebuilt a Holley 2280 carb in place of the 6280 feedback carb and installed a plain old Mopar vacuum-advance distributor with lighter springs on the weights and an advance-limiter plate in it.

But I just put a new mechanical fuel pump & filter on it in February and the pressure is anywhere from 2 psi to 6 psi depending on the outside temperature and engine temp. I'm tired of fighting with mechanical fuel pumps. I just want a reliable, quiet, consistent fuel-delivery system for my 318 daily driver.

As always, I look forward to your good advice.

Thanks.

 

[Oldiron440]

I like using a return line on my fuel system, you will need a return regulator but that’s not a problem. Just make sure both lines ( to and from the tank) are the same size.

 

[Dippy Daddy]

I like using a return line on my fuel system, you will need a return regulator but that’s not a problem. Just make sure both lines ( to and from the tank) are the same size.

Hey OldIron440,

How did you build your system? What parts did you use? And what mistakes can you tell me to avoid? Thanks.

 

[Duke5A]

Something is wrong. A mechanical pump should be all you need for such a simple setup. You can try going with an electric if you want, but there is a lot involved with it. To answer your question, yes, you can use the factory return if you want. The feed and return on these cars were both 5/16". The vent is 1/4" and can't be used for anything other than venting into a charcoal canister.

It's not all hardline back to the tank. There is at least one corner where it's rubber hose and then goes back to hardline.

You might want to ask around too. Walbro pumps aren't exactly known for being quiet. I have a 255GPH internal pump on my car and it's a noisy critter.

 

[Oldiron440]

On my Fairlane I used all Quick Fuel parts, pump, filter and return regulator. I hard lined from the tank to the rt fender well then braided line to the carb and back to the tank. It’s feeding my 450 hp small block so it’s all 1/2”.
I don’t remember just why I used braided line back to the tan but everything was done with the advice from Quick Fuel.

 

[Oldiron440]

The basic concept of the return regulator is similar to the HVLP paint guns, low pressure and high volume at the carburetor. you have more fuel at the point of consumption…lol

 

[AMC Diplomat]

The mechanical pumps are cheap and plentiful NOS. You can get them for less than $20 with tax and shipping.

I'd trust the eccentric to run a mechanical pump more than I'd trust the wiring in a 36 year old car to run an electric pump

 

[Dippy Daddy]

Something is wrong. A mechanical pump should be all you need for such a simple setup. You can try going with an electric if you want, but there is a lot involved with it. To answer your question, yes, you can use the factory return if you want. The feed and return on these cars were both 5/16". The vent is 1/4" and can't be used for anything other than venting into a charcoal canister.

It's not all hardline back to the tank. There is at least one corner where it's rubber hose and then goes back to hardline.

You might want to ask around too. Walbro pumps aren't exactly known for being quiet. I have a 255GPH internal pump on my car and it's a noisy critter.

The mechanical pump I installed in February was good for a few months, and now it's putting out less & less pressure. As I mentioned, sometimes it's as low as 2 psi, and it doesn't seem to hold any fuel in the system overnight. In other words, I drive the car through the day, I park it in my garage, and the next morning I have to pump the gas pedal four or five times to get gas in the carb. Once it's running, I can shut it off 30 seconds later and it'll start right up like a fuel-injection car, immediately. So I just want a consistent 5 psi to the carb. Mechanical pumps just don't seem able to deliver that anymore.

 

[Oldiron440]

It totally depends on what your combination and expectations are. There is a good video by David Friburger on mechanical fuel pumps, everything from cheap replacement pumps to race pumps. Your fuel pump can cost you hp.

 

[Dippy Daddy]

The mechanical pumps are cheap and plentiful NOS. You can get them for less than $20 with tax and shipping.

I'd trust the eccentric to run a mechanical pump more than I'd trust the wiring in a 36 year old car to run an electric pump

Where are you finding mechanical pumps for less than $20? I paid almost $30 for the last one at an Autozone store. Regardless, it's been in the car for about six months and doesn't seem able to deliver the pressure it did when it was new. I'm just tired of changing out mechanical pumps and want reliable, consistent fuel pressure.

 

[Dippy Daddy]

On my Fairlane I used all Quick Fuel parts, pump, filter and return regulator. I hard lined from the tank to the rt fender well then braided line to the carb and back to the tank. It’s feeding my 450 hp small block so it’s all 1/2”.
I don’t remember just why I used braided line back to the tan but everything was done with the advice from Quick Fuel.

Well, my 318 is probably churning out about 160 horses, so I think 5/16" fuel line is gonna be fine! Do you know how much pressure your fuel pump puts out? Since I want to use the factory lines in my Fifth Avenue, I want to make sure they can handle 12 psi without breaking. Thanks.

 

[Mikes5thAve]

Where are you finding mechanical pumps for less than $20? I paid almost $30 for the last one at an Autozone store. Regardless, it's been in the car for about six months and doesn't seem able to deliver the pressure it did when it was new. I'm just tired of changing out mechanical pumps and want reliable, consistent fuel pressure.

Carter is $21 on Rock Auto. Are you sure it's a pump problem and not something else? They don't need much pressure but anything from a dried out hose in the line to a blockage can cause issues.

 

[AMC Diplomat]

Where are you finding mechanical pumps for less than $20? I paid almost $30 for the last one at an Autozone store. Regardless, it's been in the car for about six months and doesn't seem able to deliver the pressure it did when it was new. I'm just tired of changing out mechanical pumps and want reliable, consistent fuel pressure.

Ebay

Make offers or let the sellers send you an offer. You'd be surprised how many people want to get rid of this stuff