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Discussion Starter #1
ok guys here is the back story.

2009 LMM Duramax

Came to us with a DPF delete and an Edge module. We replaced the problematic edge with a minimaxx. soon the owner wanted an mp-8, despite our warnings. soon enough he had no fuel delivery and the dreaded ENGINE REDUCED POWER mode

so we ported the rails, put a FASS 150 on it, BHD fprv, Industrial Injection 42% CP3 and a Garret Powermax Stage 2 Turbo, fuly deleted all of the EGR components (not just block off plates...)

It fired right up but actually gave us a FRP too high code as it was idling around 15000 psi. so we regulated the fuel delivery down to 8psi or so and it became very happy. the owner test drove it and under full boost it blew the stupid intake horn off. we pulled the truck back in and got it re attached and clamped down. when we fired the truck back up it shot up to 28,900 PSI at idle on the rail and sticks there under any throttle amount. we swapped the fuel pressure regulator from the II CP3and his stock CP3 with zero change.

we plugged the MP-8 in and when we turn it up the rail pressure drops to 24k at idle.

the only code we see now is 0090 (two of them) Fuel Pressure Regulator.

could something electronic be telling the FPR to stick wide open?

when we fired the truck back up i noticed one of the main engine cotrol harnesses wasnt atched completely closed. could that have shorted a circuit in the system?

We figured this would solve our
 

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oh also, on inspection there is a tiny nick in one of the wires coming out of the plug into the CP3. the wire isnt severed by any means, just some of the copper wire is exposed. could this throw off the volt/amp signal enough to just stick the CP3 on full pressure at idle?
 

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voltage test on both wires going to the CP3 (at the cp3 pig tail connection) yielded no signal.


sound like an FICM malfunction?
 

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could something electronic be telling the FPR to stick wide open?

when we fired the truck back up i noticed one of the main engine cotrol harnesses wasnt atched completely closed. could that have shorted a circuit in the system?

I think yes, definitely something is telling the ECM to ramp up fuel pressure.

Sounds like the wiring to either the FPR or the fuel pressure sensor (more likely) was damaged during the test drive.
I'd inspect all the wiring very carefully and test the sensor for resistance.
 
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