Electric fuel pump

[Superbirddoug]

When adding an electric fuel pump can you leave the mechanical fuel pump on? Meaning the electric pumps thru the mechanical and the mechanical pulls thru the electric. If either quits you still have fuel.

Thanks in advance

[cudabob496]

Seriously doubt it.  Unless maybe you gut the mechanical.

[Skunkworks Challenger]

When adding an electric fuel pump can you leave the mechanical fuel pump on? Meaning the electric pumps thru the mechanical and the mechanical pulls thru the electric. If either quits you still have fuel.

Yes, it will work that way.  I have three vehicles plumbed like that including my 70 Challenger.  I do find that in heavy throttle the mechanical pump does not keep up with the demand when pulling through the electric pump when it it is turned off.    When this happens I flip on the switch for the electric and all is good. 

[CudamanTom]

Yes, it will work that way.  I have three vehicles plumbed like that including my 70 Challenger.  I do find that in heavy throttle the mechanical pump does not keep up with the demand when pulling through the electric pump when it it is turned off.    When this happens I flip on the switch for the electric and all is good.

Just curious, why don't you leave the electric fuel pump on? 
I mean I wouldn't want failure during performing a heavy throttle.

Besides, I can't help but think an "off" electric fuel pump might restrict flow anyway. But that's just IMHO.

[cudabob496]

Oh, you want both working at same time? Dang, might
give you some seriously high fuel pressures.
Holleys only need 5 to 6.5 psi.
But, maybe you can plumb in a regulator somewhere.

How about running the mechanical, then if it quits, flip a switch, and the electric comes on?

[Skunkworks Challenger]

When purchasing your electric check the output pressure for compatibility with a carburater, which should be no more than about 7.5 psi.