Low Rail Pressure

sweetdiesel

That's better
Aug 6, 2006
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Thailand
Check the plumbing on your CP3's and make sure you're not feeding one with the return of the other. It's an easy mistake to make. Both CP3's should feed from their metal .218" ID nipples (passenger side nipple), to a T, then to the fuel filter.


Ive done this:eek: Makes for some hard starting too, and would not hold rail at even 1800pw.....still ran a low 11 though:D
 

JD Dave

In way over my head
May 19, 2008
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Caledon, Ontario
Check the plumbing on your CP3's and make sure you're not feeding one with the return of the other. It's an easy mistake to make. Both CP3's should feed from their metal .218" ID nipples (passenger side nipple), to a T, then to the fuel filter.

I'll double check everything again but I have a lift pump and seperate line coming from the tank feeding each cp3. Thanks for everyones suggestions.
 

JD Dave

In way over my head
May 19, 2008
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Caledon, Ontario
thats so yesterday though....if ya aint making 1200 your just not dumping enough fuel now:D


are the lmm tips not smaller than LB7?


Dave can you run a tune with like 2700pw and see wwhat your rail is like?

The tips are smaller from what I've read. I ran a 2337 PW last year on the same setup with a stock turbo no twins and it held rail great. I tried some logs on the lower tunes and I'm having trouble holding a 2500 PW now. I'm kind of wondering if it's something in the tuning. What are your thought on putting a switch on the dual fuelers so I can go full pressure when on a wot run just to see what my log shows. If the dual fueler controller has no power do the pump go wide open. Or do I have to cut into the factory harness? I also have no ideas how to change pulse width in a tune but would like to learn.
 

JD Dave

In way over my head
May 19, 2008
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Caledon, Ontario
It would be easier lowering PW than shuting off voltage to CP3 Regulators.

Well I thought that also but I put a switch in the cab and took it for 2 wot runs and from that it's holding rail now. So wouldn't that be a tuning issue? You can see right on the log where I turned it on and off. I only did my second biggest tune because I'm a little worried about my trans because that will be the next thing to go with all of this street testing.
 

JD Dave

In way over my head
May 19, 2008
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Caledon, Ontario
duel cp3 controller? So you just turning it on or off? Sorry for the ignorance I don't understand what the switch is doing. and Just curious :eek:

I'm just shutting power off to the CP3 controller and that makes it go full power. At least that's what I think it's doing. You can tell in the logs where I turn the switch off as the pressure instantly spikes up to 29k and flat lines. I just did what Tony Burkhard told me to try. Tony is a great guy to deal with.
 

maine04max

New member
Dec 11, 2008
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the FPR on the pumps go full fuel when zero volts . its the reason alot of people test the FPR by unplugging it and checking if it goes full pressure