I’m about to start back up on getting my Z06 turbo’ed and have a fuel pump question/problem that’s been bugging me. Currently I have a Lingenfelter 255lp pump with a Racetronics Hotwire installed. No boost a pump installed currently.

The current plan is to use an ECS fuel pump block (-8 feed connection) in addition to the pump/line set up I currently have. https://www.corvetteforum.com/forums...el-system.html

*** need to add a link to a post from another thread of mine that deals with part of the fuel system***
https://www.corvetteforum.com/forums...post1592222809

The thing that’s bugging me is the wiring aspect of the new pump. Haven’t fully decided on the pump itself yet but it will be a larger external pump. I would like the second pump to be activated with fuel pressure under 40psi and turns off above that, and then a second activation when I take pressure reaches 5psi. Figuring out how to wire that and which pressure switches to use to make it happen is the problem.

I know the intake pressure one is simply a 5psi Hobbs switch off the manifold to control the power relay to the 2nd pump. The 0-40psi switch is mainly the issue. I have skimmed “google” looking for a switch that fits but haven’t currently found it. On the wiring side, I believe I would need to wire the 2 pressure switches in parallel. Would/should I wire to a separate power relay or tie into the same power relay trigger as the intake pressure switch?

And a smaller question, with running a larger external pump, would installing a boost a pump even be worth doing?


I realize after typing that I will probably be asked why have the pump come on at 0-40 psi. I need it for fuel line priming as my current feed line is fairly large. -10 AN I should resize that but don’t want the added expense currently and feel by priming the system will be the most effective, least costly method. Extra pressure switch/relay/wiring verses new -8 line/filter adapters/hose ends.


Appreciate all of the knowledge of the board!

 

 

It does have issue priming. I have a check valve installed but possibly on the wrong end of the line. I will give a quick run down of the fuel setup below.


Out of the stock fuel hat, I have a GM to -6 fitting, into a gauge adapter*, then a -6 to -10 adapter, then the -10 check valve.
From the valve I have a -10 fuel line ran through the rocker to the drivers fender well where I have a -10 fuel filter with stainless mesh, then -10 to the rail.
At the rail I have a -10 to -8 tee fitting, 1 tee directly threaded to the rail, -8 cross over to the pass rail.
Rear of rails I have -8 ORB fittings to each side of the regulator, then -6 to the factory feed line.
Stock filter removed, and 2 GM line adaptors together to connect the factory feed to the factory return line to fill the fuel bucket.
*at the fuel gauge fitting off the fuel pump hat, I have an orfice fitting to a -6 fitting and hose to a GM line fitting connected to the factory siphone pump line.

I was thinking that the check valve was in the correct spot, as that’s where the factory valve is at, and it wouldn’t bled as much pressure back through the siphon system.

I should be able to move the check valve up to the fuel filter area to see if it will hold pressure better but I have my doubts. That’s why I was going to use the 2nd pump to help prime the lines.

 

Couldn't you run a hobbs switch to activate the pump above a set psi and then run an alternate path with a relay and dash switch so you can turn that pump on manually for start up?

 

I could but I’d rather have it “automated” and not have an unsightly switch. Plus if I let someone else drive the car or something, I’d rather not have to go through explaining how to “get it started.”

I want my cake and eat it too lol

 

 

I’ve let 2 friends drive it before, and my wife started it. I was in the car with the friends at the time.

 

Ok so next suggestion is to run two individual circuits with independent relays and hobbs switches. The first is a normally open switch that closes at say 5 psi and the second would be a normally closed switch that opens at 40 psi. The 5 psi switch would be vacuum/boost referenced and the 40 psi switch would be fuel pressure referenced. Then you could run your 12V constant to power each relay, signal wire from the OEM pump 12V wire, and then run the 12V output wire to each switch and then to the pump.

It works in my head but I may be missing something. Honeywell makes factory set and field adjustable switches that should work for this. I wish Bret would chime in with all his wiring knowledge.

 

 

I have to cycle nearly a dozen times for it to start to hit. Once it runs, if I turn it off, it will fire right up.