Instructions for running fuel system for efi...

95CobraStang

Member
Jan 21, 2004
281
1
18
Chico, CA
Hey everyone-

I am looking for instructions for plumbing a whole new efi return fuel system. My car is nothing but a shell, so I am starting from scratch. I have a new fuel tank, and thats as completed as my current system is. Are there any instructions?

This is what I think I need to do:

1. In tank fuel pump (obviously wire it...inertia shut of..etc)
2. run lines to where engine will be
3. Run a return line
4. Add adjustable fuel pressure regulator

Is that it?? I'm thinking Aeromotive fuel rail as well. FYI- a 302 will be receiving the fuel.

thx.
 
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Alright did this this summer so it is still pretty fresh. I bought a roll of 3/8 aluminum tubing, braided -6an stainless steel with hardline adapters, adapters for -6an to the stock Ford fuel rail (both return and pressure), Holley Red adjustable fuel regulator, fuel pump, and a brass NPT fitting for the return plug on the gas tank.

From here I ran the pressure up the passenger side and had it go into the engine bay inbetween the solenoid and battery. Used a hardline/-an coupler to start running the braided stainless attached the appropriate fitting and then used a -AN adapter to the stock fuel rail.

For the return, I had just done the fuel system in aluminum 2 years ago so it was fine. I only had to use the NPT fitting into the drain plug and then use the braided to extend the return to the fuel rail again using an -AN adapter to stock rail.

Also remember that if you are using any rubber line, it must be Fuel Injection rated.
 
95CobraStang said:
Hey everyone-

,,,, I have a new fuel tank, and thats as completed as my current system is ,,,,
This is what I think I need to do:

1. In tank fuel pump (obviously wire it...inertia shut of..etc)
,,,,
thx.

What kind of new tank do you have? Is it like the stock one?
 
Taranis said:
Question: When running the return line, does it have to be the same size as the pressure line or can it be smaller? 1/2" pressure line and a 3/8" return line?

from my experience running return lines on other EFI cars, you want your return line to be at least the same size, idealy it should be a little larger, I found that when I ran the same size return line as feed line on my turbo neon, when I let off the gas the exhaust would crackle and pop if you know what I mean, but that issue was fixed when I went with a larger return line, I'm pretty sure it has something to do the fuel pressure changing when you have a vacuum referenced FPR(IE the FPR sees either vacuum or boost and adjusts fuel pressure to compensate, then when you let off the throttle throttle suddenly it returns to a near nuetral condition, lowering the fuel pressure suddenly, so if there isnt enough volume in the return line the fuel backs up momentarily, causing a temporary rich condition, which causes exhaust popping and crackling) I dont think that this is really all that bad(other than being annoying) but its easiest just to run a slightly larger return line and be done with it


as far as what the best way to run the pump is, I am personally going to go inline...its easiest and works well for many cars NA or forced induction....though interstingly the Merkur XR4TI(turbocharged) uses both an in tank and and in line fuel pump, though I cant see any real advantage to that other than 1. having a backup pump if one goes out and 2. each pump only has to work at a 50% duty cycle...since the fuel flow will still only be as the highest flowing pump(say you have an in tank 155lph and an inline 255lph, you will only have a total 255lph flow, but with 2 pumps the inline pump will only have to work half as hard to flow its maximum amount of fuel....which isnt worth the cost, but is interesting)
 
My 2 cents, I have tried both types of fuel pump, enternal and external. the external was a T-Rex 255 it had a 10 micron filter before the pump, it was very noisy and the car seem to be lacking fuel, do not know if it was because of the filter,

On the other hand the internal pump came out of a 1991 Mustang 5.0L. I bent the fuel pump to look like the 66 seding unit from the side. It also had a 255 fuel pump. I had to resolder the metal bracket. The internal pump works great, you can barley hear the pump.. The only problem is the fuel sending gauge it don't have one,.... I was in the process of attaching it to the pump I will let u know how it comes out..

I did pick up an extra internal fuel pump bracket from a 1991 mustang at the junk yard for $25.00 so I can modify to fit a 66 and maybe attach the sending unit.


good luck