When I first started buying them they were dirt cheap. Now they are about $2k-up on the GM websites.
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Help please!! Cp4 issues
- Thread starter dylon333
- Start date
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Exactly. I used to pay 1650 for them. Now I pay little over 2000.
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At those prices it might not be such a bad idea to buy an LML that gets traded in cause owner doesn’t want to deal with it
In my experience, GM will raise prices on engine related parts over time as that particular model gets old enough to be out of any possible warranty
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Crazy rail pressure
The rail pressure is all over the place at idle and under load. Any where from 2k to 10k psi just sitting there. Truck “lopes” if you will. This was the original problem before cp4 decided to die. Got brand new gm pump on it and still has same issue. Thinking it’s almost got to be a rail pressure sensor. No fuel coming from regulator on the rail when truck is acting like this. Unplugging rail sensor it seems to run smoother.
The rail pressure is all over the place at idle and under load. Any where from 2k to 10k psi just sitting there. Truck “lopes” if you will. This was the original problem before cp4 decided to die. Got brand new gm pump on it and still has same issue. Thinking it’s almost got to be a rail pressure sensor. No fuel coming from regulator on the rail when truck is acting like this. Unplugging rail sensor it seems to run smoother.
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Thanks cocker got the pump and got it put on this weekend! Got the truck back up and running. Still having rough idle but started a new thread for that. Really appreciate you getting it shipped out so fast for me! Dissembled old pump and couldn’t Find any obvious failure.
Ive combined your threads. keep it together here since this is all running together under basically the same issue. keeps guys from asking the same questions in the other thread that were already answered here.
So I went ahead and put a rail pressure sensor in it on a guess because it was cheap. No go. I unplugged the number 2 regulator. The one on the drivers rail, truck died, restarted the truck, truck was in limp mode, but rail pressure was stable and truck ran smooth. I’m starting too think the 2 regulator is the issue, mainly because it’s the last piece of the system that hasn’t been replaced yet. Any other input?
What are you referring to as the #2 regulator? The return side?
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Fuel pressure regulator #2 was the culprit. (The one on the front of the drivers side rail).
So long story short when I pulled the number 1 regulator from the pump there must have been a piece of dirt drop into the pump and cause the pumps failure. But my original issue of the fluctuating rail pressure was caused by the #2 regulator. But now we have a brand new cp4, rail pressure sensor, and a new #2 regulator. All for less then 500 bucks.
So long story short when I pulled the number 1 regulator from the pump there must have been a piece of dirt drop into the pump and cause the pumps failure. But my original issue of the fluctuating rail pressure was caused by the #2 regulator. But now we have a brand new cp4, rail pressure sensor, and a new #2 regulator. All for less then 500 bucks.