fuel injection return

[bear]

What size return line should I have put into my fuel tank? I am working on a 2.4l fi system?

[tekenaar]

Originally posted by bear What size return line should I have put into my fuel tank? I am working on a 2.4l fi system?

The single MOST IMPORTANT thing to remember about return fuel lines is that they should ALWAYS be sized so that they give no restriction to fuel flowing back to the tank. The reason for this is simple, if you restrict return fuel flow in any way, it becomes part of your fuel pressure regulation system! You DON'T want this!

That said, general recommendations are to have return lines sized at least 75% of the injection pressure line size. Racers play it safe and use the same size for both . . . not a bad idea.

[tekenaar]

Oh yeah, make sure that the tank "nipple" to which you attach the return fuel line does not restrict return fuel either!

[bear]

thanks for the info, just to clairify, I should make the return as big as the feed line? Also where should I have the return put? The tank has a "tit" on the passengerside rear. There is a hole in the floor of the car at that same spot if I am not mistaken.

[tekenaar]

Originally posted by bear thanks for the info, just to clairify, I should make the return as big as the feed line? Also where should I have the return put? The tank has a "tit" on the passengerside rear. There is a hole in the floor of the car at that same spot if I am not mistaken.

Yes.

The only problem with using one of the existing vent nipples on a gas tank other than the '75 tank (designed for FI and won't fit GT) is that you will have noise (splashing sound) from the returning gas. Since the vents are at the top of the tank, the more empty the tank, the louder (echo) the noise is.

A word of warning about the '73 GT tank: Under NO circumstance use the tank's "vapor return" nipple (smaller line from the fuel filter back to tank on the '73 models only) for reason already explained!

A lot of people make up a new "T" for the filler neck hose with the nipple welded in it. Sound will be isolated from tank because it does not directly "splash" into it.