EFI Return Fuel Line - Trying to shake the ignorance

[Dray]

Hello,

I am dropping an EFI 426 into the challenger in a couple of weekends  and while I have most of the parts, it has occurred to me that I need to set up a return fuel line.  So my questions are as follows:

1) Where does the return line hook into so I know how big a length of fuel line to purchase?
2) On the return line, does the size matter that much?  ie 5/16th or 3/8th?
3) I am assuming buying the fuel line from NAPA or some equivalent local auto parts company is sufficient?

Cheers,
dray

[Chryco Psycho]

at the end of the rails you need a pressure regulator from there you need a steel line from the end of the rail all the way back into the fuel tank
 As far as size 1/4 " should work but over kill cannnot hurt so I would use 5/16
 you can get a roll of steel tube from Greggs dist or a local parts store like Dash for cheap & bend it to fit

[moper]

The size depends more on the regulator and pump assembly. If the pump has an internal return, you can run a small line. If it doesnt, and the regulator is the only return source, you should run at leas tthe same size return line as feed line. It will give a steadier supply of fuel at the right pressure, and keep the pump cooler on the street and under light throttle or cruise conditions. That can be a big deal on a high pressure system. I use braided hose at minimum. Not 10' of rubber hose, or steel line with rubber clamped sections of rubber. The pressures you are dealing with will be 4-10 times as high as a typical carbureted setup. So plan accordingly.

[matt63]

Not to hijack this thread but what kind of connections are acceptable for the higher pressures of EFI fuel pumps?  For example, I have a low pressure electric fuel pump that is connected to steel fuel line via a short piece of the blue rubber hp hose.  It is just pushed on and clamped.  Is this suitable for EFI service?
I was going to flare the end of the tubing but there wasn't enough room to get the flaring tool in otherwise I would of had to remove the whole line.

[Dray]

Thanx CP and Moper.

I am not sure if Tim sent me the regulator with the weldon fuel pump and dial-a-flow controller.  Hmmm, since the parts are at my dad's I think will have to wait until the weekend before I can find out.   

Cheers,
dray

[Chryco Psycho]

Factory style connections are O ringed & locked together AN fittings are probably the best aftermarket solution
 you may get by with double clamps & & flared line , I would not trust an unflared line at 55 psi

[moper]

Factory style connections are O ringed & locked together AN fittings are probably the best aftermarket solution
 you may get by with double clamps & & flared line , I would not trust an unflared line at 55 psi

I'll add, get full wrap EFI hose clamps. They dont pinch the hose, and can hold much higher tension. Definately have to put some kind of flare on it...

[Autophile]

I recommend a return line diameter that is the same as the feed line diameter. The EFI system will be hard to tune or may not run at all if there is too much fuel system back pressure. Let the regulator determine the system pressure.