Quick fuel pump question

[Earley Motorsports]

What pressure do the mechanical pumps run and is there much difference between a Pegasus one and one from a local parts store like Advance or Autozone.
Thanks as always, Graham.

[DanW]

It's about what your carb wants - 2 to 4 PSIG for a weber DGV.

[Earley Motorsports]

Thanks Dan

[kea]

Weber carburetor settings are based on fuel pressures being no higher then 3.5 lbs.
Fuel pump volumn is the question, as one of my F/Ford customers found out at the Run-offs this year.

[Earley Motorsports]

Thanks Keith. Does 12 gph sound about right?
Graham.

[kea]

Sounds good to me but I'm not an engine builder.
Maybe you should make a call and ask yours.

[Earley Motorsports]

Thanks Keith

[Lee Follansbee]

OK, the less work the engine has to do to power subsystems, the more usable power is available to the Wheels. With an electric pump you can not only be very selective for pressure but also volume, as many options exist. Just like tuning a carb, just upstream a bit. And they are just as reliable as a mechanical pump.

So you are probably at a wash weight-wise, and yes the battery has a bit more load on it, but it doesn't care. And you get more HP at the wheels... Oh, and you can put lines in a more accessible place for assembly/disassembly. Not really any downside that I can see.

[Neil_Roberts]

Not really any downside that I can see.

With a mechanical pump, fuel flow stops when the engine stops. With an electric pump, fuel flow increases dramatically when a fuel hose is severed or a connection starts leaking. Indycars and Champ cars are required to use a mechanical fuel pump for exactly this reason.

[Steve Demeter]

When I ran elecrtic fuel pumps I ran an oil pressure switch that when the oil pressure went below 10 psi, it cut off power to the pumps. Had a toggle switch to bypass for atarting.

About 20 bucks from longacre.

[Earley Motorsports]

Thanks for the comments guys. I have an electric pump in my 7 which has an injected Toyota 20 valve in it. It has a switch built into the AFM so when the motor stops sucking air, the fuel pump stops. I have seen a video of a seven being raced and the guy crashes it and the pump just keeps on running then all of a sudden "poof" up she goes. The on board camera caught it all. The guy was already out of the car when it went up. Having some sort of a safety switch is a must.
Thanks again, Graham.