So here's MY story. I've got an 02 with 175k. Injectors replaced under the warranty at about 105k. I now have a truck that is pretty low on power, and has a "miss" when under load. I threw the Mac scanner on it and shows decent balances on the injectors, but only about 12k of the required 28k of line pressure. Stealership is telling me that the injectors are fine and that the FPR is bad, got that replaced still no different. They NOW tell me the injector pump is bad....I've bever heard of a pump "going bad" but only pumps the straight up "FAIL". Anyone have any insight?

I have never heard of a CP3 just up and failing, not pumping any fuel to the common rail. However, many people, including myself have had a CP3 slowly loose its ability to maintain commanded rail pressure. I replaced mine just a couple of months ago after throwing a p1093 (low rail pressure) code for over a year. What all do you have done to the truck? A big tune without a lift pump will mirror the problems you have here. Fill out your signature and we can help even more.

At what point did you see the low fuel rail pressure? Was this at idle or when you were hammered down on a 100% throttle run?

We did it both at an idle as well as at WOT. The highest we saw was just over 13k and it's sportin about 10.5k at an idle. Hopefully the new info in my signature is enough to help you help me.

That sounds high for idle and low for WOT. My rail pressure is only around 4 or 5k at idle. It could be a bad connection with the FPR, if that connector isnt seated correctly or becomes disconnected the pump faults out to max pressure. With only getting 13k rail pressure though, I would say its a prime candidate for a weak pump, because I highly doubt the edge is draining the rail.

If the connector on the pump was bad, wouldn't it command full rail pressure? If so, I would say it is possible you have a weak pump.

It might have only been 4 or 5k at idle, I could very well be mistaken. So you guys are saying that the high pressure injector pump is weak then? I've found one for $665 in Oregon but I didn't want to replace it if I didn't have to. I just still find it hard to believe that I have a pump that is starting to get weak.

Well if your only seeing 13k rail pressure max at WOT, something is wrong. Did you replace the FPR or the dealer? I would check the connector to the FPR just to rule that out. I know it seems senseless to replace the pump after replacing the FPR, but its the best route to go, money wise. About the only other thing that could cause the low rail pressure is the injectors. Have you been able to pull any codes off from the truck? Usually bad injectors will throw both the p1093 and p1094 codes, where if the pump is weak it should just throw a p1093. A lot of guys on here have went down this road, and its just a hard problem to diagnose because of all the parts that could cause the codes and poor performance.

THe dealer replaced the regulator, I will gladly check the connection though to eliminate one thing. Where is it located? LOL
I pulled codes, I remember p1093 for sure, but I didn't/don't have a 1094 code.

A good pump can pump enough fuel to cover up a weak injector so that is not always a cut and dry way of diagnosing the problem.

If I was you, I would go back on the dealer for fixing a part/issue on your truck and not being correct. You paid them to fix a problem and their solution didn't work, get your money back and tell them to pound sand.

I've heard of bad injectors causing the CP3 to show low pressure. An injector could have high return rates that why you can't command it to 160 Mpa since it would be bleeding off pressure.

I've taken it to both stealerships here in town and they've told me the same thing, "your injectors are good, it's your high pressure pump that needs replaced." THe way I see it, I really don't have much of a choice but to replace the pump and see what it does then. Right? I guess if that doesn't work, I will go back to Chevy and tell them that my injectors are bad so they can replace them AND reimburse me the cash I've got into it b/c they've told me it was bad.

I've taken it to both stealerships here in town and they've told me the same thing, "your injectors are good, it's your high pressure pump that needs replaced." THe way I see it, I really don't have much of a choice but to replace the pump and see what it does then. Right? I guess if that doesn't work, I will go back to Chevy and tell them that my injectors are bad so they can replace them AND reimburse me the cash I've got into it b/c they've told me it was bad.

You are in the same boat as my friend, they told him the same thing. I would almost bet you that once they replace your injection pump you will get a call saying your injectors are bad. I could be wrong as this is only a "hunch".

Good luck getting a dealer to give you money back for a misdiagnosed condition...my buddy is getting ram rodded as we speak because of the mistake.

Have they done a injector return rate test? This is not something that can be done by a computer or scanner so my guess would be no...

I guess I'll go forward with buying/replacing the injector pump and just see what happens. Anyone replace on of these themselves?
Anyone heard any negative about http://www.o-f-i.com/index.php?pid=14 or have a source for a better deal?

I guess I'll go forward with buying/replacing the injector pump and just see what happens. Anyone replace on of these themselves?
Anyone heard any negative about http://www.o-f-i.com/index.php?pid=14 or have a source for a better deal?

Replacing one isn't that tough, just takes time. You won't need any real "special tools" IMO.

As for a source, contact Tony Burkhart who is a vendor here. His company is All Season Sales and Service. He has a source for take off engine parts and I know people who have bought pumps off him before and always got a good product.