[indymanjoe]

Originally Posted by Shiny

Here's my pump. I don't see a brand so probably a generic short-can.

The filter was my band-aid to try and get the car running in spite of rust.

I bought a new carter high volume from butler at the Pontiac nationals 140 this past aug.

i put a robmc on instead 550hp version ( i forgot i had the robmc,bought from a member here) That pump made a huge difference at the track.
if you want the new one from butler 100shipped. lmk

[Schurkey]

Originally Posted by Formulabruce

The stock pump bypasses excess pressure to the return line to tank, leaving 4-5 psi to the Q jet.

No, it doesn't.

There is no "excess pressure" to return to the tank, because the pump is incapable of producing "excess" pressure. A pump with a vapor return that produces 5 psi at the carb, would maybe produce 6 psi if the vapor return was blocked.

The "return" is considered a "vapor return", readily passes fuel vapor, but is heavily restricted in terms of liquid fuel. The fitting in the pump probably has a .060 hole, or smaller, that the vapor squeezes through readily, but presents a restriction to the more-viscous liquid fuel. (Photo attached.) Internally, that "return" fitting probably has a stand-off tube that goes to the upper part of the fuel pump liquid chamber, where the vapor is more-likely to be (and the liquid fuel is less likely to be.) I saw photos of this stand-off tube in the last couple of months, but I don't remember which web site, or who posted 'em.

Originally Posted by Formulabruce

If a fuel pressure regulator adjustable from 4-7 psi Took the Place of the factory pump, and the electric pump left ON with key, will the SECOND output of the regulator ( has one in and Two out) act same as stock mechanical pump as a return line?
CARB engine, LOW fuel pressure..
Anyone tried this on a stock style engine?

You could do that...but the output of the regulator that feeds the vapor return tube would have to be restricted to .060 or less; matching the restriction built-into the engine-driven fuel pump. Otherwise all your fuel gets blown back to the tank.

What's more important is that it would be a waste of time, money, effort, and enthusiasm to bother with the restriction and the vapor return on a PUSHER electric fuel pump. The whole reason to have a vapor return is that the engine driven fuel pump is 1) hot, 2) "sucking" (reduced pressure) on the fuel tube going back to the tank, and 3) that fuel plumbing may be getting heated by the exhaust system. All of those promote fuel boiling in the suction (reduced pressure) plumbing. The vapor return is a crutch to get rid of the vapor and prevent vapor lock. The pusher pump runs cooler, and doesn't "suck" on the warmer parts of the fuel plumbing; and the warmer sections of the plumbing are under higher pressure--so there's no vapor and no vapor lock.

[Shiny]

Originally Posted by indymanjoe

I bought a new carter high volume from butler at the Pontiac nationals 140 this past aug.

i put a robmc on instead 550hp version ( i forgot i had the robmc,bought from a member here) That pump made a huge difference at the track.
if you want the new one from butler 100shipped. lmk

Thanks for the offer but I'm holding off on replacing my pump. I'm not sure there is any issue with the one I have and I don't need anything more than stock performance. I think the pump I installed ~15 yrs ago is an older style Airtex 40679 so probably nothing wrong with it.

Mike