Efi Fuel System In A 68


Jul 16, 2011
I got the wiring done in my 68 fastback thanks to you guys on stangnet, and now im working on a fuel system that isnt 500$. I have looked at a few websites online, but will like help. Any pics would be appriciated and inventory of parts used. I have a stock except for a e303 cam,1991 mustang motor going into my 68. I want to keep it simple.
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i just ran another fuel line right down the side of my original for the return line.
i then drilled my filler tube and fish hooked a piece of metal fuel line in so it extended down in the tank and brazed it in ,out side of the car of course .i attached the new line to it using fuel injection hose that came up through the rear trunk brace so it ran down the side of the filler tube through the floor .i used a Holley fuel injection electric fuel pump just after the fuel tank ,mounted to the frame rail and attached it to the old fuel line .the front was simply hooking the fuel line and return line to the correct line ,once again using fuel injection fuel line . did it in just a few hours. this was in a Mustang for a friend,i did a Ford truck the same way ,simple and worked great.
The fuel pressure regulator is that vacuum can-looking thing on your '91 fuel rails, probably on the passenger side. It is referenced to manifold pressure and ensures that fuel pressure across the injectors doesn't change. It regulates that pressure by varying a bleed that sends fuel back to the tank, hence the return line. Newer systems use "dead head" systems and various electronic means to control pressure now, but the state of technology 25 years ago didn't make it practical then.

I have been trying to decide what to do for the EFI fuel system in my own '68. I'd like to just run a return line and plumb it simply, but I also hear that the old tanks and pickups can suck air under hard cornering, thus needing a different tank or a separate surge tank/"swirl pot."
After two grueling months, finally heard the engine roar. Thanks guys for all your input. Still have to clean up the electrical and a few things here and there.


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