I need some help diagnosing a problem. I have a standard F150 that I supercharged. I just added the Lightning fuel hat and Y to my truck. I'm using a Boost-a-Pump to power the second pump. Both are new 255 lph pumps. The second pump runs full time on the BAP but increases pressure at 4 psi.

Under normal idle conditions I have about 50psi now. When I give it light throttle it drops to about 45 psi. Then under WOT, it drops to 40 psi where it will stay.

I can't figure out why I have approx 50 psi at idle, which shows the second pump has added more pressure. But then it acts like the regulator never adjusts to increase the pressure at WOT. With the BAP kicking in at 4 psi, the pressure should go way up, but it never does, it just stays at 40 psi.

Is it because one pump is possibly over powering the other and forcing the fuel back through it? I have confirmed they are both working by unplugging each one. 1 pump alone shows about 20 psi due to fuel being forced back through it when the other is unplugged.

Any ideas?

 

Derrick - I am assuming that you have the Aeromotive adjustable fpr?
I still look at the mixed voltages as a probable cause. The flow of the pump which has the bap over-driving it has 70% (?) more flow at the full voltage of 17v. I could only see ~11v to my pump without the bap, a known issue with the stock wiring.
I would try bypassing the bap to that pump and set the adj fpr to the 39.5 psi at idle with both pumps working, then check at cruise and wot, carefully.

 

I bought a dual pump boost a pump today.
Hopefully this remedies the problem. But I still want to try to test a few things to see if that is without a doubt the cause of the issue.

 

Are you running returnless or full mechanical return fuel system?

 

As of now the system is stock after the pumps. Stock rails and stock regulator with 42lb injectors.

 

Ok, so it's a returnless system. Are you referring your stock regulator as the FRPS (Fuel Rail Pressure Sensor)?

How do you actually have your 2nd pump wired? Anyway you could draw a diagram and scan it or take a picture and post up?

 

The 2002 is a return style system.
Currently I'm still using the stock regulator set at stock psi.
One pump is currently running off of the stock wiring. The second pump is operating off of the boost a pump that is triggered by the fuel pump relay. So when the stock pump kicks on, the boost a pump engages at a normal 12v to run the second pump. Then at 4 psi it goes to about 15 volts at which point I"m thinking it overpowers the stock wired pump.

 

I'm officially stumped......I added the twin BAP this weekend and am now running both pumps off the BAP. Still no more fuel pressure. It stays at 40 under throttle. Why is it making 50 at idle but no more than 40 under throttle?
At idle it sits at about 50 psi, and I can activate the BAP manually and it will spike to about 60 so I know the BAP is working and you can hear the pumps increase.
Why is the fuel pressure not going up under throttle?

 

Hey Derrick,
I heard from onelowf that you might have a set of 42 lb injectors you might want sell?
I am interested for a 1998 4.6.
Thnaks, martinpasqualone at comcast dot net.

 

take it to PM's, stop hijacking the thread

 

how do the pumps merge into the fuel line??


I have a Y and both my 255's full tilt all the time but I honestly need to check the FP

 

Have mine the same. I'm thinking the Y is restricting the flow. That's the only thing I can come up with. I'm about to remove it and got two -6an lines to a Aeromotive filter then -8 line all the way to the rails.