LB7: Help Pinpoint 1093 issue

[Csibbs]

Hello all,

Been battling this issue for a week or so now, and slowly going crazy.

Truck has been throwing a 1093 for quite some time now. Been slowly chipping away at it to pinpoint the issue, with no luck so far.

Truck has 250k on it.
2002 Silverado 2500hd
Edge cs2 but has since been removed to find the issue.
Smokes every once in a while at idle through the pcv. White smoke. Not a lot

Symptoms I'm having
Truck is very slow, can not get out of it's own way.
Not a lot of black smoke at WOT
When the truck is colder, under half throttle it commands around 18kpsi but will reach about 13kpsi.

When the truck is warmed up, it will command 23kpsi under throttle but no matter what the pedal position is, it never goes above 10kpsi, give or take.

CEL does not illuminate for these codes.
P1093
P1094
And last night for the first time a U1800 code that hasn't come back yet.


Here is what has been done:
Replaced collapsing rubber fuel lines.
Changed fuel filter
Checked injector balance rates.
Checked vacuum at idle, and under WOT.
Idle vaccum reads 4"
WOT vaccum reads 8-9"

Checked wiring to FPR and FICM

Attempted to command max rail pressure last night using a snapon solus, the truck did not react to this at all. Just stayed at 35mpa when 160mpa was being commanded.

Using the scanner with the truck running, I turned the FPR relay on and off. Which just shut the truck down.

However, with the truck off and the relay energized, the FPR seemed to have an electricial hum, almost similair to a tattoo machine. Like an energized coul but very spring like sounding.

This is as far as I've gotten. My brake line blew out last night so that is first on my list.

I'm going to dig down into the valley this week and check for voltage drop to the FPR.

There is also a return line from the cp3 in the valley that appears to be starting to collapse. I will replace that as well.

Thinking about just replacing the FPR if voltage is good to the sensor, being that I'm already going to have to tear into the truck.

Any reason why it wouldn't react to the scanner when rail pressure was commanded?

 

[ZeroGravity58]

Being that the truck has 250k its probably due for injectors, a cp3 or both at this point. I don't think your problem is in the wiring. If you unplugged the FPR it should max out the rail pressure if the cp3 and injectors are healthy.

 

[DAVe3283]

Sometimes scanners don't play as nice with the 2001-2002 trucks as later trucks. The early OSes were picky. Since the scanner doesn't want to work, just unplug the FPR. That will result in max pressure. If it can't hit 160 MPa at idle with it unplugged, you have a mechanical problem. Usually a bad FPR just causes surging and delayed pressure, not low pressure. So it is probably a CP3 or major fuel leak.


That's where I'd start.

 

[clrussell]

I’d borderline put money on it being then cp3. Unless the injectors are just trashed

 

[Csibbs]

I’d borderline put money on it being then cp3. Unless the injectors are just trashed

In all honesty, I think it's the cp3 as well. Just doing all that I can before tearing into it.

I know that balance rates don't tell you much when dealing with rail pressure unless I do a return test but here's the balance rates at idle

Inj 1 -0.9 Inj 2 0.4

Inj 3 -2.6 Inj 4 0.2

Inj 5 0.0 Inj 6 1.3

Inj 7 1.8 Inj 8 0.3

 

[clrussell]

Is it hazing out the exhaust? Making oil? Mileage On injectors?

If no, no, non originals injectors. Stick a cp3 on it. It’s due

 

[Csibbs]

Is it hazing out the exhaust? Making oil? Mileage On injectors?

If no, no, non originals injectors. Stick a cp3 on it. It’s due

Not making oil, oil doesn't smell like diesel either. No Haze out the exhaust either.


Still on original injectors as well
.my issue is that I really can't shell out the type of money for both. Even if I were to do that myself. So at this point I would rather pinpoint the issue and take care of that. Although it seems particularly hard to do

 

[GMC-ya!]

I had the 1093 code for quite a while and it wouldn’t reach max psi. Put a new cp3 on and it made a huge difference. Truck in my signature and I replaced the cp3 around 200-220k miles if I remember right.

 

[ZeroGravity58]

You can pick up a used cp3 and swap it in for a couple hundred bucks. See if that fixes some of your problem if it won't hold rail pressure. Look around the for sale section there was a few in there. If you do injectors, only put in GM or LDS rebuilds. Don't go with the cheap places or you will be doing the twice

 

[Csibbs]

You can pick up a used cp3 and swap it in for a couple hundred bucks. See if that fixes some of your problem if it won't hold rail pressure. Look around the for sale section there was a few in there. If you do injectors, only put in GM or LDS rebuilds. Don't go with the cheap places or you will be doing the twice

Good idea on the used cp3. Just afraid of getting a bad one and being out a few hundred bucks.

Either way, does anyone know the part numbers for the gaskets I need?
I believe there's a gasket on the housing of the cp3
The gaskets on the coolant crossover for the thermostats
And the intake horn gasket

 

[clrussell]

Good idea on the used cp3. Just afraid of getting a bad one and being out a few hundred bucks.

Either way, does anyone know the part numbers for the gaskets I need?
I believe there's a gasket on the housing of the cp3
The gaskets on the coolant crossover for the thermostats
And the intake horn gasket

The gaskets are reuseable as long as they aren’t trashed in removal. Minus the intake horn gasket, it’ll likely tear.

 

[Csibbs]

Ended up buying a used working cp3 and regulator. Going to install it next Saturday. I will post an update. Can't tell you how many threads I came across that had me wondering what fixed their issue

 

[N2BRK]

too bad I didn't see this sooner. My buddy bought a used 12mm from this forum and his is perfect - just going to upgrade fuel and turbo. You could have swapped right here at my house into a known good stocker.

 

[Csibbs]

Welp. Swapped a used cp3 into the truck and it fixed my issue. Now time to install a lift pump. Too cold out to do that tonight but I'll get around to it