I'm running dual 450lph pumps with a 8an feed and 6an return thru an Aeromotive regulator. The second pump is set to come on at around 5 psi with a pressure switch. The regulator also has the boost reference hose connected.

How would I go about adjusting the base fuel pressure that I need (58psi) on this setup? Do I need both pumps on?

 

I run same pumps, same regulator, same fuel line sizes, on my E85 fueled car, fwiw.
210# injectors.

Although, i run both pumps on, full time, and see absolutely no negatives doing so.
My fuel pressure would spike, when 2nd pump was boost referenced. Mine is and was easier to dial in with both pumps on, full time

I had heard, or read, that the Walbro 450's didn't like higher pressures, so I run my base fuel pressure at 45psi.

Setting fuel pressure should be done with the vacuum/reference hose removed.

 

Yeah Chris1313, who's pump assy I'm using said it's fine to run both full time so I think I'm gonna do that. Car is also a non DD anyways. Thanks for the heads up on the base pressure, I will try that when we get ready to retune it.

 

Thats where my pump setup came from as well.
Some say the fuel gets overheated with both pumps on. That is not what I have experienced.

 

I have staged pumps on a Hobbs. I dry tested it by turning on the main pump, set pressure, then manually activate the second pump by shorting across the Hobbs switch while observing pressure. It jumps one psi. Which when under load during a pass becomes invisible.

Also should note I’m -8 feed and return.

Maybe think of it this way. Double the flow, all that fuel needs to bypass into a smaller fuel line. The pressure spike is caused by the smaller return line. I learned that 30 years ago when I built the fuel system on my car when it had an NA rat motor in it.

With the exception of much larger pumps now, the system is still the same.

Ron

 

Haha lots of coincidence! Yeah this car is mostly a weekend car and I occasionally do cruises with it so its never on the road more than an hour or two at a time... should be ok I think.

 

I would never run two 450s full time especially if it's driven on the road for more than 30 minutes at a time. With a good regulator you won't even see the pressure spike when the 2nd one turns on.

 

This is very true! I turned on the second pump while it was idling at 58 psi with the primary / first pump and it went up maybe 1 psi or less. So I think I'm gonna leave it the way it is I'm using an Aeromotive fpr btw...