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Discussion Starter · #1 ·
Repost from Ford Truck forum.
Hello, I bought a 2011 F250 6.7 powerstroke at auction. It is a really nice truck. When purchased I had a cylinder imbalance in #4. I parked the truck in the driveway and went through the M pinpoint test, I discovered it was the fuel injector. After pulling the injector I discovered the IQA wasn't programmed into the PCM. Since I had ordered the new injector, I just replaced it and programmed the IQA. Now the truck won't start giving me a P2291 injector control pressure to low - cranking. I double checked everything. It's good. The only thing I did different from the M test was I don't have the equipment to do a relative compression test. I pulled all the glow plugs and did a manual on all the cylinders using a starter auxiliary bypass switch. With the engine cold I was getting at least 300 PSI on all the cylinders. I don't know if the bypass switch may have killed something. Back the M pinpoint test, I am getting plenty of fuel from the low pressure fuel pump and it's clean. I can pull up the pids and control the F_PCV and F_VCV but I don't know what the lowest duty cycle or highest duty cycle is and I don't know how to observe fuel flow from the left hand fuel rail. How does one do that? What is the lowest duty cycle and highest duty cycle? I changed out the Pressure control valve because it was the easiest. Still P2291. I took the intakes off and looked at the VCV, the screen was clean. I checked all the fuses, they were good. At this point I'm down to two components the volume control valve or CP4 pump. Can a CP4 pump fail non catastrophically?
Any help is appreciated.
 

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I haven’t seen a CP4 fail in the manner which you describe. What is your actual cranking fuel pressure vs desired? What is the FRP pid KOEO?
 

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Discussion Starter · #3 ·
I haven’t seen a CP4 fail in the manner which you describe. What is your actual cranking fuel pressure vs desired? What is the FRP pid KOEO?
From the FRP pid starts out at 4359 (approximately) and when cranking goes to 8300+ . The low pressure I haven't measured but I can dump almost a gallon from after the engine fuel filter in the 30sec of KOEoff. I don't think low pressure is my problem and there is definitely no air in the system.
 

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Discussion Starter · #4 ·
I read the VCV is wide open (guessing low duty) at 0 volts. So logic would have at high duty I would have voltage and the valve would be slightly closed. If the PCV is the same low would open and high would be closed. To test my theory, I disconnected the line from the right fuel rail that supplies fuel. I hook a piece of hose to and ran it to a bucket. M test 16 says command the PCV to low duty cycle (open) and VCV at low (open) should observe fuel and high (closed) should not. That worked flawlessly. The VCV works as far as I can tell.
M test 15 says to command the VCV to low (open) and the PCV should flow fuel when at low (open) and stop when duty is high (closed). That did not work. I just put a new one of these on; however, I did buy it off Amazon, but the bag was sealed so... I could not convince myself the part was bad so I wanted to test the connection via multimeter. With the FPL_CMD on and VCV low, I cycle the PCV pid from 0 to 100 and always got approx 7.28 volts the whole time. This maybe one of those instance where you need an O scope since the valves are controlled by the PCM, but I would think I would get a steady voltage if I'm controlling the PID. I just don't know enough to say the wires are good going to the valve.
From that, does anyone have a suggestion?
 

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If you have 8300 on actual (matching desired) that is plenty to start, it needs 5000 psi to start. Is that 4300 ACTUAL KOEO? If so, you likely have a bad sensor or wiring.
 

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Discussion Starter · #8 ·
Just to clarify, what’s your ACTUAL vs DESIRED fuel pressure KOEO, and cranking?
I believe Key on Engine off FRP was 4300. When cranking started it jump to 8300+. I will need to put the intakes back on to verify that. I don't have time until Saturday afternoon. In the meantime, I just did a return to Amazon. When I get the intakes back on, I will verify and post.
And Thank you.
 

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The ECM has a fuel pressure that it commands. It usually is displayed by FRP_DSD.
But KOEO should be very close to if not zero for actual. 4300 is way too much. Check the wiring pigtail closely also
 

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Discussion Starter · #12 ·
So I put the intakes back on and looked a the PIDs. FRP_A_CMD sits at 4389 with KOEO and when cranking jumps to 5734+ but FRP_A reads 0 regardless. So I am still not building pressure. With the PCV not operating like the M test say it should, I will wait for a new one to arrive and see if that one cooperates before moving on unless there is something else I can check for.
 

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You should have more than 0 , low pressure fuel pressure should show up. Did you try unplugging the sensor and see if it would run?
 

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Just to clarify, your actual measured FRP KOEO and cranking is 0?

Also are you SURE your low pressure side is fully functional?
 
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