Mechanical fuel pump to in-line electric fuel pump

[robsim111]

Is it possible to use mechanical Holley 90gph fuel pump to bolster pressure to a fuel injection electric fuel pump? I made a post previously about an in-line pump wining, and I believe it's because it's having to pull too hard from the tank. Would using mechanical to pull from the tank to feed to an electric starve the electric and fuel injection?

I'm running stock 302 (~240hpi) with a fitech setup.

 

[Skiddy]

yeah think it would starve the pump. where is your electric pump mounted? the are more of a pusher not a puller. closer to the tank the better.

 

[AZ73]

Look at the LPH (liters per hour) or GPH (gallons per hour) ratings. PSI isn't as important as flow. I run a Carter electric back by the tank to pull from the tank, then to a Bosch high pressure electric. The Carter will move more LPH and bypasses the fuel if it's not taken up by the Bosch. For example, the edelbrock mechanical fuel pump for a 302 moves 416 liters per hour at 6 psi. That's plenty for the the Bosch which produces 80 PSI @ 255 liters per hour. My Carter produces 378 LPH @ 6 PSI more than enough for the Bosch which need 255 lph. A stock Ford mechanical pump produces about 300 lph. More than enough for a high pressure electric pump.

 

[rjlougee]

My thoughts, and I'm sure there will be dissenters...

If the mechanical fuel pump could keep a decent 302 feed with fuel, why couln't it also feed a 5.0??

In which case, it should keep the HP pump filled with enough fuel to work, just maybe not so much on the return side of the equation.

I'd say give it a try and let us know how it works, or doesn't.

And it's a FITECH, pretty much the same thing as an '85 Capri 5.0 setup.

The other half of the equation, is the whining fuel pump. I'll look for that thread and reply there.

My $.02, worth exactly what you paid for it...
Joe

 

[Jluck]

Add an expansion tank?

 

[Broncobowsher]

Mechanical pump is engine speed dependant. Electric is always full speed. At idle the flow of a mechanical pump won't keep up with the electric.

 

[Rustytruck]

Does an electric fuel pump in a fuel injection system run full duty all the time at idle or does it cycle on and off as pressure is needed?

 

[blubuckaroo]

All the electric fuel pumps I've had have had a pressure switch that would shut it off when there's no demand.
But what's being described is something like the FITech Command Center.
It lets the car's normal fuel pump fill a reservoir containing a needle valve/float setup as long with a fuel injection pump.

 

[Broncobowsher]

EFI pumps run full speed all the time. Never turn off. On some stuff, really new OEM, they might throttle back a little for evaporative emissions reasons. But never turn off unless the engine is stopped.

 

[Eoth]

Fitech will run the electric pump depending on needs. It runs less at idle and will increase as you require more fuel for higher RPMs.

 

[Jluck]

https://www.tomsbroncoparts.com/product/6698GS

 

[73azbronco]

Mechanical pump is engine speed dependant. Electric is always full speed. At idle the flow of a mechanical pump won't keep up with the electric.

Yes it will feed just fine, but I wouldn't do it that way. Remember an electric high pressure just wants flow to feed it. I think a sound electric pump should work fine all by itself, BMWs did for years with an external HP pump feeding the rails. If you feel you need the low pressure high volume feed to the high pressure low volume pump, I'd do what others suggest, a LP carter feeding the EFI pump, with an accumulator between the two and a return to the tank with a low psi check valve.

 

[ntsqd]

......

WHOA!!
Hey Joe, got any spare zip-ties? ;D

I have read of some late model systems using what suspiciously sounds like a PWM circuit to regulate fuel pressure in a dead-headed system, but I don't think the aftermarket is there. Yet.