I own a 1973 Nova that I am converting to fuel injection. The only snags I see so far are:

#1. The fuel system requires a return line. Instead of pluming a new line into the tank, would it be possible to run the return through the charcoal canister line back into the tank?

#2. I have a holley red electric pump in the back. I plan on running a high pressure pump in line up front, piggy backed behind the holley red. This should be safe as long as the holley red flows more volume than the high pressure pump, correct?

on the pump; hmmmm. I don't think I'd do this personally. Why not remove the holley red, install an inline FI pump instead and sell the holley? You will need a good return line. the canister line is too small and maybe not thick enough tubing.

I am pretty sure the canister line is the same size as the intake line ... 3/8". I just want to know if it's possible ... and why not piggyback the pumps? I think the mustangs do it.

Ok, my return line is a 5/16 line, I have two fuel pumps and I really doubt the chac. can line is too small. I could see the line getting to a few psi so I would inspect it and worm hose clamp any rubber section, replacing 1973 rubber. If the return line were to back up, wouldn't you see more fuel pressure?? Like an inverse fuel pressure regulator? Less psi under more throttle and thus more fuel usage?

Now, I think I would piggy the pumps. Since you are drawing fuel out of the tank, and this is more challenging than pushing, a bit of extra oomph couldn't hurt. Also, since a pump that goes 125 psi has tighter tolerances in which to trap dirt I am demanding a fuel filter.

As far as the red flowing more than the other pump. I think the addition of the other pump will increase the flow of the holley red and the red will increase the flow of the other and the other will be flow limited by the holley red. So I think as long as the holley red can feed the engine now than I think a more efficient engine (BSFC) and more flow on the holley b/c of the other pump will be even more adequate than it was before.

Tell ya what; I'll buy the left rear quarter panel of that '73.

I'll even be really nice and buy the rear bumper & trunklid.

Where does the canister line run after it is plumbed into the tank? Anyone have a picture?

The only concern I have with piggybacking the pumps is running the high pressure pump dry. If it is activated before the pump behind it, it will just end up pumping air. This is a good way to burn up pumps.

Why does it matter where the line runs? As long as it is above the fuel level correct? Since it is a vent I believe it is at the top.

I am assuming after the first initial priming of the HP pump fuel will stay in the line. Just have them come on at the same time.

I don't want to attempt to run fuel against some sort of internal gas tank charcoal canister check valve.