Did you check return flow from fuel rail ? rev up engine to max rpm fuel must come out ,force of pressure should open it

Wish I could say that I made more progress but...

Here is what I did today:
I put the original fuel pressure sensor back in and limp mode went away (briefly).
Monitored things using TorquePro and fuel pressure (as taken from the rail pressure regulator) looked normal. Going up and down with engine speed. The P0193 code promptly cam back.

Then I did this...



... which was stupid because I didn't plug that return hose. So I wound up dumping about a half gallon of fuel on the floor.
So I corrected my mistake and did the test again (BTW, 5/16 hose works better) and a tiny amount of fuel came out and into the bottle. And while monitoring TorquePro, fuel pressure at idle was about 5000 psi

Next, I did the injector return flow test.
At this point, the P0190 code came back along with limp mode.
TorquePro showed a idle fuel pressure of 25600 psi.
Fuel from the injector return lines filled their individual bottles at a slow trickle. But the bottles filled somewhat evenly with #2 being slightly more than the others.

So I dont know whats going on here.
It appears that the fuel pressure sensor was not the problem.
The rail pressure regulator appears to be working like it should.
And the injectors return flow seems good.

So what is left to do here?
Is it possible that the injection pump is allowing too much fuel out the return line and not sending enough to the fuel rail? And if so, how can that be fixed?

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U.S. Army Retired

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'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

well at this point you need a wire diagram to check it properly, possibly bad connection ? ecm harness sensor harness ? loose or damaged wire ? continuity test ? i know takes time to trace wires , good luck

I had one where the pin for the sensor was toasty at the CPU. And, if it's an 06, you know about the wire pinching problems behind the fuel head. Just a thought, I haven't got back through this thread yet, but maybe inspect the pins, and clean them with the 93%+ (I forgot the exact concentration) alcohol and a tiny brush if you think it could be the problem.

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05 CRD: H.D.S2 stat,WW Ironrock trilink&LCA's, OX rear,ARB front, 4.10's, ARB bumper, Suncoast,OME 3.5, JBA UCA,rock rails, Moabs&265/75 Duratracs, GDE tunes ,FFD fan,ARP's, 2 micron fuel, new valves,sasquatch battery tray & grid heater, tensioner relocated
Mech fan, VH & AC delete

Because the fuel pressure sensor is pretty much the same as on a Duramax and Cummins, I started searching for P0193 code solutions for those engines.

Apparently, on the D max, its common for the wiring harness connection to have loose or broken wires.
So, I checked that first and all three wires seems good.

Then I found some troubleshooting documentation for the Cummins.
Verified the 5 volt supply voltage to the sensor.
Performed resistance checks on the fuel pressure sensor and the sensor tests good.
Some of the other troubleshooting steps required the DRBIII, which I dont have, and may indicate a bad ECM.

If anyone can help me find the troubleshooting documentation and wiring diagrams for the CRD I would greatly appreciated it.

I'd also like to know how to test actual rail pressure. I'm sure there is some sort of special gauge for it but I dont know where to look.

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U.S. Army Retired

_________________
'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

Flash, I know you worked recently at your cyl head, so you took all those connectors apart, I wonder if some of the rubber dust seals those connectors have, among with some normal corrosion on the contactor pins, won't create the code. Try and take the dust covers away for a test, since this is very easy and not time consuming... On my jeep, I am running w/o electric dust seal to an injector connector and my cp3 sensor, had some random codes every now and then and took them away, never had the codes since.

Another question, when you accelerate, it throws 0193 no matter how hard/easy you go on the pedal? I wonder if the code is triggered by more engine vibrations versus being triggered by fuel demand.

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2005 kj CRD, samco, suncoast tc, provent, Kennedy lift pump, GDE ECO full torque, 2nd gen filter head, 245/70/16 a/t tires, mopar light bar, fumoto oil valve, OEM Skid Plates, ARB Front bumper and HD OME, tru cool LPD47391 40k GVW tranny cooler (stock cooler delete), FF Dynamics e-fan and shroud, rocker arms replaced, HDS2 190F thermostat.

thanks
I already had to 05 manual and it was useless.
The 06 manual had troubleshooting info for a P0190 code but not a P0193.

_________________
U.S. Army Retired

Where is the CP3 sensor?

I pulled the dust seal out of the fuel pressure sensor connector and it didn't make a difference.

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U.S. Army Retired

Don't think this is related to your issue though but the cp3 sensor, I think it's some sort of pressure regulator, is mounted on the back of the cp3 pump, I believe it's the only electric sensor the pump has.

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2005 kj CRD, samco, suncoast tc, provent, Kennedy lift pump, GDE ECO full torque, 2nd gen filter head, 245/70/16 a/t tires, mopar light bar, fumoto oil valve, OEM Skid Plates, ARB Front bumper and HD OME, tru cool LPD47391 40k GVW tranny cooler (stock cooler delete), FF Dynamics e-fan and shroud, rocker arms replaced, HDS2 190F thermostat.

hey Flash ,after all you need to go back to low pressure side (eng starving for fuel under load) hear is why , ecm is demanding high pressure to fead injectors ,but actually rail pressure is low and goes in limp mode, thats why high press code is just opposite, remove filter head off the jeep , remove all rubber hoses from fuel tank to cp3 pump check for internal collapsed fuel hoses under fuel tank .remove fuel cap blow shop air back to tank .possibly restricted in tank sending unit, or you may put fuel container on passenger floor and hook up the hose to filter head and go around the block , this is what i would do without special diagnosing tool gages etc .

I guess it cant hurt to to check.
I can also test flow by just letting the lift pump flow into a bucket.

The very first thing I did when trying to fix this was replace the rubber fuel line that feeds into the filter head. It had been rubbing against a bracket and had a deep groove cut into it. Not quite leaking but almost there.

_________________
U.S. Army Retired

With a cheap vacuum gauge you can also check the suction on the low pressure size by holding a tappered/cone shaped adapter into the line while someone cranks the engine. If you did this all the way back at the tank, maybe it will tell you about any problems in between? I did this after the filter to verify good suction of a suspect CP3. In the end, it ended up being that pin at the CPU. It was so charred that I had to scrub it with a tiny piece of sand paper and SLIGHTLY bend the pin to make it make contact as the receiving side was damaged by the heat as well. Oh, I put a tiny bit of contact goop on it, and I mean tiny.

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05 CRD: H.D.S2 stat,WW Ironrock trilink&LCA's, OX rear,ARB front, 4.10's, ARB bumper, Suncoast,OME 3.5, JBA UCA,rock rails, Moabs&265/75 Duratracs, GDE tunes ,FFD fan,ARP's, 2 micron fuel, new valves,sasquatch battery tray & grid heater, tensioner relocated
Mech fan, VH & AC delete

i can't wait to see results , when you put fuel can on passenger floor and go for test drive

_________________
'05 CRD Limited
Pricol EGT, Boost
GDE Hot '11; EDGE Trail switched
SEGR; Provent; Magnaflow;
Suncoast T\C, Transgo Tow'n'Go switch;
Cummins LP module, Fleetguard filter, Filterminder
2.5" Daystar f, OME r; Ranchos; K80767's, Al's lifted uppers
Rubicons, 2.55 Goodyears
Four in a row really makes it go

hi Flash did you get any luck with fixing your jeep ?

Not yet.
Here is what I've got so far...

Low pressure side looks good.
I let the lift pump pump from tank through main filter and into a bucket. Flow was strong and steady with no bubbles.

Pressure sensor tests good and so does the rail pressure solenoid.
Did continuity checks from both to the ECM and the wiring is good.

So I think I have narrowed it down to:
1. The fuel quantity solenoid on the CP3
2. The CP3 itself.
3. The ECM.

It just seems to me that the CP3 is sending too much fuel out the return and not enough to the rail. But its hard to know for sure without proper gauges.
I just want to know exactly what the problem is before I start throwing parts at it.

_________________
U.S. Army Retired

ok ,good ,go with step 1 (replace prop valve)

Extremely good writeup GMCTD, I have saved it for future information if ever needed which I hope not...

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Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited
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Yeti StgIV Hot Tune
Week's BatteryTray
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2mic.Sec.Fuel Filter
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