Ideal lift pump pressures

[Wikid]

Hey guys, So if anyone has followed my project cracked piston build, I got it started up recently. It started without any issues warmed up and drove around fine.

Some background on the system.
Sump from the fuel tank to -8 to AD2-165 then -8 to 12mm cp3

The return is -6 from the cp3 to a return block with the injector returns then -6 back to the fuel cooler

the fuel rails have ported fittings, drivers side is .125 and the passengers is .062

This morning I started it up and it was about 20 degree colder than it had been every time it had been running. The issue was that on my EDGE CTS is listed the FRP at 23kpsi. So i pushed on the throttle a little hoping it would go down and it did until it reached what was being commanded.

When it warms up it idles about 1-2kpsi higher than what is being commanded.

long story short after researching and testing the cause is the lift pump(AD2 165). at the moment I am not sure what the pressure is in the line just that the pump is still at factory stock settings which should be 8-10psi. I have ordered a gauge so I can plumb it into the feed line and see what it is.

My question is when adjusting the lift pump what should I be looking for, obviously I dont want my new CP3 to be building 25kpsi at idle. Should I adjust the pressure down until the FRP matches the commanded FRP? but keep it high enough that it doesnt drop to 0 at WOT on the race tune?

Wikid

 

[Ne-max]

Sounds like a tuning issue. Or your fpr is not hooked up.

 

[Wikid]

Sounds like a tuning issue. Or your fpr is not hooked up.

FPR is connected that I did check, and already talked to Rob about the tuning. When i disconnect the lift pump the rail pressure matches what is being commanded. I found quite a few instances of people having the same issue where the lift pump was causing the higher rail pressure.

 

[wilsondiesel]

Hard to tell until you have a gauge to see what the lift pump is putting out. I work for Air Dog in the class 8 pump devision but when setting a pump up for basically a stock cp3 truck try to set them up around 8 psi. Though you're running a 12mm pump, I'd have to call Exergy and see what kind of psi they'd like to see up to it.

 

[Ne-max]

FPR is connected that I did check, and already talked to Rob about the tuning. When i disconnect the lift pump the rail pressure matches what is being commanded. I found quite a few instances of people having the same issue where the lift pump was causing the higher rail pressure.

That pump would have to be really cranked up to get to 27k.

 

[Ne-max]

Hard to tell until you have a gauge to see what the lift pump is putting out. I work for Air Dog in the class 8 pump devision but when setting a pump up for basically a stock cp3 truck try to set them up around 8 psi. Though you're running a 12mm pump, I'd have to call Exergy and see what kind of psi they'd like to see up to it.

Every raptor we hook up we have to turn all the way down. Always are around 16psi out the box.

 

[Wikid]

I already shot an email off to exergy asking but it was past closing time so I wont hear anything until monday anyway. And the gauge is going to take some time to get as well. I have a cheapish gauge I can screw into the line but its in the engine bay and wouldnt say there otherwise it would just die.

I think another thing is that I am not using the stock fuel lines from the tank to the CP3 I replaced all the steel hard line with -8An line and it goes straight into the CP3 no looping around where the filter used be type of stuff. So i am thinking its getting more fuel that it used to as well.

I figured the CP3s would be happier with more fuel but i guess they are not designed to be force fed.

 

[aashton1206]

We for the lb7 you want as close to 7psi as possible at idle based on my hardware.


2004 Silverado Cali lb7, Airdog ll 165, fresh sticks at 325k, custom tuning on v2 by Rick Fletes, 33x12.5 nittos at on 20 inch American steal wheels, modded factory air box, Profab Intake Horn, Batmo Wheel, Turbo port and polish, Full EGR Removed w/ fed belt, 3.5 inch MBRP Downpipe, Full five inch MBRP Exhaust, 10mm lbz cp3 pump, Dual Yellow Top Optimas, High Output Alternator, Cognito Pittman and idler w/ support kit, Cognito Contol arms, Drilled and Slotted Rotors on all four Corners, Custom Y Bridge.

 

[moparkxracer]

When you look at the cp3 pumps on their sight they call for 8-10 psi to ea cp3.

 

[gmduramax]

Unplug the air dog. Do you still have the same problem.

 

[Wikid]

Unplug the air dog. Do you still have the same problem.

As i stated in the OP , no the problem goes away once the AD is turned off and its just in pass-through. So i know the AD needs adjusted I was just trying to figure out what the best process is for setting the pressure.

should I just turn it down until the actual matches the commanded or is it normal for the actual to be slightly (couple hundred PSI over not KSPI lol) over the commanded with a lift pump.

I dont want to go so low that at full throttle the lift pump pressure is at 0.

 

[RickDLance]

We always ran the most lift pump pressure we could get away with. Too much and it would start loping at idle.

 

[Awenta]

^I agree with Rick. Just turn it down till it stops loping. 10psi or so will work. Shouldn't have a problem keeping up.


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[Wikid]

So ran to the auto parts store and picked up a cheapo fuel pressure gauge and threw it on my inline port fitting. it was sitting at 14psi. I backed the adjustment all the way out and it bounces between 9-10. The lope seems to be gone, you can still unplug the lift pump and it will make the engine and exhaust sound different. but not a heavy lope like it was.

My new sensor coming will tie into my EDGE so I can log what it does going down the track. I think it will be fine, I feel it had a lot to do with the fact that its got a straight shot to the CP3 now.

 

[aashton1206]

What year truck are you running


2004 Silverado Cali lb7, Airdog ll 165, fresh sticks at 325k, custom tuning on v2 by Rick Fletes, 33x12.5 nittos at on 20 inch American steal wheels, modded factory air box, Profab Intake Horn, Batmo Wheel, Turbo port and polish, Full EGR Removed w/ fed belt, 3.5 inch MBRP Downpipe, Full five inch MBRP Exhaust, 10mm lbz cp3 pump, Dual Yellow Top Optimas, High Output Alternator, Cognito Pittman and idler w/ support kit, Cognito Contol arms, Drilled and Slotted Rotors on all four Corners, Custom Y Bridge.

 

[Wikid]

What year truck are you running


2004 Silverado Cali lb7, Airdog ll 165, fresh sticks at 325k, custom tuning on v2 by Rick Fletes, 33x12.5 nittos at on 20 inch American steal wheels, modded factory air box, Profab Intake Horn, Batmo Wheel, Turbo port and polish, Full EGR Removed w/ fed belt, 3.5 inch MBRP Downpipe, Full five inch MBRP Exhaust, 10mm lbz cp3 pump, Dual Yellow Top Optimas, High Output Alternator, Cognito Pittman and idler w/ support kit, Cognito Contol arms, Drilled and Slotted Rotors on all four Corners, Custom Y Bridge.

06 Silverado 2500HD Ext cab LB

 

[aashton1206]

06 I usually set right at 10 psi. From the factory many lifter pumps are calibrated for 12, though I have seen some ad systems come at 14 from the factory and need to be calibrated. I use an air dog myself, fast, those are usually right at 10 but they are easy to adjust as well.


2004 Silverado Cali lb7, Airdog ll 165, fresh sticks at 325k, custom tuning on v2 by Rick Fletes, 33x12.5 nittos at on 20 inch American steal wheels, modded factory air box, Profab Intake Horn, Batmo Wheel, Turbo port and polish, Full EGR Removed w/ fed belt, 3.5 inch MBRP Downpipe, Full five inch MBRP Exhaust, 10mm lbz cp3 pump, Dual Yellow Top Optimas, High Output Alternator, Cognito Pittman and idler w/ support kit, Cognito Contol arms, Drilled and Slotted Rotors on all four Corners, Custom Y Bridge.