fuel pressure regulator return line questions

[dans78c10]

Hello experts... hoping to get some advise on what I am thinking about doing here. (I have looked over posts here, hope I am not re-hashing something that has been answered).

Background info:
78 c10, 350 engine, stock mechanical fuel pump pumping 10+ PSI to my new edelbrock 1406 carb.
(Needs to be 5.5 PSI as per edelbrock instructions, so will be installing a regulator).

I have looked at many regulators, and am leaning towards an Evil Energy brand, (best quality/reviews for the money, I believe).

Finally my question... This regulator utilizes a return port (shown at bottom of pic)

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I would like to run a line from this return port... to the steel line that previously ran to the charcoal canister at the front of the engine bay... which I removed. The line is still there, and runs to the the smaller line on the fuel sender unit at the tank.

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Has anyone used this line for a fuel return port, or think this would work ???

 

[nvrenuf]

I’ve never done it like that but it sounds like it should work fine UNLESS that tube does something weird on the interior side of the sending unit.

 

[xm20k]

Are you sure about that pressure? I currently run an aftermarket 110GPH pump and it only just hits 6psi most stock pumps Ive tested/ran would only hit 4-5psi I've never had to run a reg on a mechanical pump.

If your sender only has two ports that second is your vent so the tank can "breath" a reg on that line could cause it to be unable to pull fuel. Going to the newer 3 port sender could be setup to run a return reg.

 

[dans78c10]

I am sure about that pressure. The gauge I used to test it (with engine running at idle) only went up to 10 psi and it was pegged. The fuel pump is from my local oreillys.

I understand that the line is a vent for fuel vapors in the tank to be sent to the charcoal canister as a means to re burn it, rather than just release it to the atmosphere. My plan was to just get a vented gas cap to vent the tank.

Your guy's comments got me trying to remember what the other side of the sender looks like, I put it on new last september. I looked up a pic of the sender and it does have some kind of fitting/filter/valve on the inside end of the tube (see pic).

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I was just assuming it was an open ended tube that would allow fuel to be dumped back into the tank.

Thanks guys for getting me to think about that. I will leave the 2 port unit on, it works fine and the gauge works good now. I am now going to try to fine a quality dead-head style regulator to install.

 

[75gmck25]

My first reaction is that you are going to a lot of trouble to add a regulator, when the simple fix is a new fuel pump that has the right pressure.

Supposedly you can also drill the sending unit and install a fuel return fitting. YMMV

 

[Ricko1966]

Push comes to shove you could install a bulkhead fitting in the tank. I can tell you how to do it without dropping the tank.

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[Grit dog]

Seems getting another fuel pump that doesn’t make Olympic caliber pressure would be much simpler, easier and cheaper. Free, maybe. I’d return the pump as defective if you bought it recently.

 

[CalSgt]

My first reaction is that you are going to a lot of trouble to add a regulator, when the simple fix is a new fuel pump that has the right pressure.

Supposedly you can also drill the sending unit and install a fuel return fitting. YMMV

Seems getting another fuel pump that doesn’t make Olympic caliber pressure would be much simpler, easier and cheaper. Free, maybe. I’d return the pump as defective if you bought it recently.

^^^^ This

You’re creating a whole new potential for problems by not just using a correct fuel pump

 

[dans78c10]

Sadly, I put the oreillys pump on last august when I first got the truck and was trying to get it up and running. Had the old quadrajet on at that time, and too much pressure didn't even cross my mind as a problem... until I put on the edelbrock.
The bulkhead fitting would for sure work.

I just got a different 0 to 15 psi fuel pressure gauge and am going to install it just before the carburetor and get a double check on the pressure. I'll post the PSI results then.

Thanks everyone for the replys and ideas, much appreciated... I'll keep you posted.

 

[Smtty58]

The return line on the sender has an anti-rollover valve, basically a check valve thats normally open unless it's upside down.

 

[dans78c10]

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Second check with different gauge shows 10 psi. I really appreciate the replies, and suggestions from everyone, I have checked for other pumps that will give the ideal 5.5 psi that the new edelbrock needs to run right. All are above that with the exception of edelbrock's pump, which maxes out at 6, but at $183.00 not an option for me.

I am going to try a Holley regulator, which doesn't need a return to the tank.
After everything you guys pointed out, using the vapor line would not be a good idea.

I am thinking the regulator would be an easy install, cost effective, and enable me to dial in just the right pressure needed.

 

[NLD79K10]

My solution was to install a Holley returnless fuel pressure regulator, seems to have held up for the last year or so.

 

[dans78c10]

That is encouraging to hear. Thanks.

 

[Grit dog]

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Second check with different gauge shows 10 psi. I really appreciate the replies, and suggestions from everyone, I have checked for other pumps that will give the ideal 5.5 psi that the new edelbrock needs to run right. All are above that with the exception of edelbrock's pump, which maxes out at 6, but at $183.00 not an option for me.

I am going to try a Holley regulator, which doesn't need a return to the tank.
After everything you guys pointed out, using the vapor line would not be a good idea.

I am thinking the regulator would be an easy install, cost effective, and enable me to dial in just the right pressure needed.

Man, a new fuel pump is like $30-40.
I can’t say I’ve ever put a pressure gauge on one in the almost 40 years I’ve been dinking around with old cars but I’ve never had one over pressurize.
Avg mech fuel pump is supposed to be 5-6 psi. Cant say why yours is an over achiever but you’re finding solutions for problems that generally don’t exist.
The Eddy carb on my 77 runs fine on whatever is hooked to the side of the motor. Just like the thousands of others driving around today and millions before that.

 

[NLD79K10]

@Grit dog True, the average mechanical fuel pump is supposed to be 5-6 psi, sadly maintaining consistent output specs during manufacturing isn't considered important nowadays and you'll see pumps throwing out anywhere from 4 to upwards of 7 psi.