P0192 and air in fuel head HELP

ericg88 · **Joined:** Wed Apr 03, 2019 8:34 pm **Posts:** 16

The Jeep is showing code P0192 "Fuel Rail Pressure Sensor A Low" and I have been experiencing intermittent power loss that feels like a quasi limp-mode of some sort.

It is still drive-able and starts up quickly, but power and acceleration is extremely bad after 45-50 miles an hour, though I can still get up to highway speeds eventually. It seems reluctant to go above 2000 RPM, but it will slowly creep above as I gain speed. If I try to give it full throttle the RPMs will shoot up to around 3000 RPM but will not delivery any more power at all. Also, when the symptoms are showing, when in park or neutral the engine "lopes" or "surges" and it seems like it's barely able to stay running, though it seems to stay running indefinitely in this state.

This doesn't happen all the time, sometimes I can drive as much as 25 miles to work without any symptoms, but it is happening frequently.

I checked the connections to all the sensors/solenoids I could find on the rail and couldn't find anything that looked burnt or damaged. From what I've read, if it is a bad electronic, it should be the Fuel Pressure Sensor, as a faulty solenoid wouldn't allow any pressure at all to build in the rail.

I am able to get pressure with the manual primer pump on the fuel head (old style fuel head), but I haven't seen any diesel seeping from the head or any of the lines while it's under pressure. It doesn't seem to stay pressurized very long, maybe a minute or two. Is this normal or should it hold pressure?

When I bleed the head I do have air coming out for the first 2 or 3 bleeds, then it's all fuel. But when I drive the jeep/let it idle for a few minutes and bleed again I get the same amount of air as before.

I put on a new UFI fuel filter (made sure to remove old gaskets), didn't see any cracks on the fuel head, and the fuel heater plug doesn't seem to be burnt or melted.

These symptoms started after I installed the upgraded Thermostat Housing from Hot Diesel Solutions. The Thermostat seems to be operating perfectly, and I don't know why this would affect the fuel system, but maybe I tore a wire or cracked a plug somehow?

I know these jeeps are notorious for Air-in-fuel issues and I've had a hard time finding detailed info about P0192. I saw one post by GRE that said this means an open circuit on the Rail Pressure Sensor. The contacts look normal but I'm not quite sure how to test if the sensor is working or not. Is there an easy way to test this sensor before I buy a new one, or before I try a lift pump of some kind?

flash7210 · **Posted:** Mon Mar 09, 2020 7:17 pm

When checking the connectors on the fuel filter head, you won’t see cracks or anything burnt/melted. What you will see is a slight hint of wetness on the tip of the plug. That indicates a leak.

If you are still using the old style fuel filter head, replacing it would be a good place to start.
Also consider adding some sort of electric fuel pump.

A few years back I had a difficult time with a p0193 code.
After testing or replacing nearly every fuel system component, I discovered that the problem was with the connector at the fuel rail pressure sensor.

So, start up the engine and let it run at idle.
Then wiggle the pressure sensor connector.
If the engine sputters or stumbles you’ve found the problem.

ericg88 · **Joined:** Wed Apr 03, 2019 8:34 pm **Posts:** 16

Thanks for the response, flash.

I tried wiggling the wires to the Fuel Pressure Sensor and didn't see any effect.

I double checked the connectors for the Fuel Temp Sensor and Fuel Heater... Yeah.. The Fuel Heater connector is a little wet. And Actually I got some sputtering from the engine when I wiggled it while plugged in.

I spliced in some clear tubing coming in and out of the filter. Initially I saw a small but steady stream of air bubbles coming from the tank side, but after a minute or two this subsided and I only saw an occasional air bubble passing through. It looked free of air going from the filter to the CP3 the entire time, though. I expected to see air going to the CP3... especially if it's leaking from the heater plug or some part of the filter head.

I am going to order new filter head, as I think this one might be the original. I bought the jeep last year with only 55k miles on it, but even with low miles that plastic head won't last forever in southern heat.

Is it worth upgrading to a Racor or does the updated head function well?

WWDiesel · **Posted:** Tue Mar 10, 2020 2:26 pm

If you want to end all air in fuel issues for good, install an intank fuel pump as many owners have done.
Any leaks anywhere will be self evident very quickly once you install an intank fuel pump since it will leak fuel out of the leak instead of sucking air into the fuel system.
The intank pump puts the entire fuel system under pressure from inside the fuel tank all the way to the back of the CP3 injection pump.
Many have reported their engine seems to idle smoother after installing the intank fuel pump, an added benifit.
Your Jeep CRD is already wired all the way to under the rear seat and has relay and control logic in the ECM for an intank fuel pump from the factory.
See this:> http://www.auerbach.ca/kj/lift_pump/

:SOMBRERO:

ericg88 · **Joined:** Wed Apr 03, 2019 8:34 pm **Posts:** 16

Hey WWDiesel,

Do you think the air in the line is what is tripping my P0192 code? I am planning on getting an in-tank pump sooner than later, as almost everyone seems to have air-in-fuel problems sooner or later, but I want to figure out and fix whatever is tripping this code first. It just bugs me that the symptoms started after I installed a new thermostat. I dunno how that could affect the fuel system but maybe I bumped a sensor or tugged a wire too hard. The jeep also sat for a month during this same time, so maybe air just crept into the system. Never had any of these symptoms before that.

From what I've read on here, most of the time this code is associated with the Fuel Pressure Sensor. I've wiggled the harness and connector and it doesn't seem to have any effect. I haven't looked at the ECU end yet. Is there a way I could test the FPS to see if it's working properly?

flash7210 · **Posted:** Tue Mar 10, 2020 9:19 pm

The best way to test the fuel rail pressure sensor is with a OBD scan tool that can read fuel rail pressure.
I use a ELM327 Bluetooth adapter with my Android tablet running torquepro app.

WWDiesel · **Posted:** Wed Mar 11, 2020 4:19 am

ericg88 wrote:

Hey WWDiesel,
Do you think the air in the line is what is tripping my P0192 code? I am planning on getting an in-tank pump sooner than later, as almost everyone seems to have air-in-fuel problems sooner or later, but I want to figure out and fix whatever is tripping this code first. It just bugs me that the symptoms started after I installed a new thermostat. I dunno how that could affect the fuel system but maybe I bumped a sensor or tugged a wire too hard. The jeep also sat for a month during this same time, so maybe air just crept into the system. Never had any of these symptoms before that.
From what I've read on here, most of the time this code is associated with the Fuel Pressure Sensor. I've wiggled the harness and connector and it doesn't seem to have any effect. I haven't looked at the ECU end yet. Is there a way I could test the FPS to see if it's working properly?

Have you checked all the grounds? I would also check the wiring very closely especially where the harness runs behind the alternator and over the top of the engine. There has been one or two reports of some rubbed wires bare and shorted out in this area.

I would defer any questions about fuel rail sensor issues to Flash or Gordnado.
Gordnado has a post that covers everything about the fuel system sensors if you can find it.

this one covers it a little:
viewtopic.php?p=925357&sid=1e26dbd9e7713da1e03f44702a7c5284#p925357

ericg88 · **Joined:** Wed Apr 03, 2019 8:34 pm **Posts:** 16

Thanks a lot for the help, fellas.

I ordered the updated OEM fuel filter/wiring kit last night, should be here in a couple days.

I will check the grounds & reexamine all the wiring closely some time this week when I get the chance to do it properly.

I'm also going to go ahead and order a Carter lift pump and try to rewire my original harness as soon as I can find the right terminal parts. I found the part numbers for Jameco on another LOST thread but the female piece seems to be unavailable. I'm going to call Jameco today and find out which piece they recommend as a replacement.

WWDiesel are you still selling brackets/kits for the secondary filter setup? I plan on installing a secondary filter after I get the lift pump installed.

Thanks again for all the advice!

WWDiesel · **Posted:** Wed Mar 11, 2020 11:26 am

ericg88 wrote:

Thanks a lot for the help, fellas.
I ordered the updated OEM fuel filter/wiring kit last night, should be here in a couple days.
I will check the grounds & reexamine all the wiring closely some time this week when I get the chance to do it properly.
I'm also going to go ahead and order a Carter lift pump and try to rewire my original harness as soon as I can find the right terminal parts. I found the part numbers for Jameco on another LOST thread but the female piece seems to be unavailable. I'm going to call Jameco today and find out which piece they recommend as a replacement.
WWDiesel are you still selling brackets/kits for the secondary filter setup? I plan on installing a secondary filter after I get the lift pump installed.
Thanks again for all the advice!

Yes, I still have a couple of the *secondary fuel filter mounting brackets in stock or I can supply you with the complete kit to install a *secondary fuel filter & gauge.
(*Must have a lift pump installed)

As to the wire terminals, Mouser Electronics has all the wire terminals:
Wire Terminals: APEX 2.8MM
male, 14-16 gauge wire
female, 14-16 gauge wire

https://www.mouser.com/Connectors/Autom ... bwZ1z1414h

or
you can order a new OEM gasser wiring harness or go to a bone yard and get one off a gasser Liberty, that goes from under the rear seat connector to the top of the fuel tank. (May have to rearange the pins a little on the gasser connector?)
Sasquatch Parts also sells the complete intank kit or just the wiring harness.
https://shop.sasquatchparts.com/product ... y-28l-crd/
https://shop.sasquatchparts.com/product ... berty-crd/
05 & 06's are different so be sure and get the correct year model for your vehicle.

TKB4 · **Posted:** Wed Mar 11, 2020 12:20 pm

Sounds like you have a good plan to eliminate all the air in fuel possibilities as well as provide better filtration of fuel. The thermostat is not related to the problem unless the wiring sensor involved not the thermostat itself. If the older style Fuel filter head in place it needs to be changed anyway for fire protection etc and u will need the wiring connector too unless you live in warmer climate ( the only difference is for the heater element connector). Maybe the fuel head change will correct the problem till you get a convenient time to do the rest. Congrats on researching the problem here before you even asked for suggestions. Even when I am pretty sure I know what to do it helps my confidence tremendously to have other viewpoints .

ericg88 · **Joined:** Wed Apr 03, 2019 8:34 pm **Posts:** 16

WWDiesel wrote:

As to the wire terminals, Mouser Electronics has all the wire terminals:
Wire Terminals: APEX 2.8MM
male, 14-16 gauge wire
female, 14-16 gauge wire

https://www.mouser.com/Connectors/Autom ... bwZ1z1414h

I ordered the male and female terminal pins (and some extras) and the extractor tool a couple hours ago, total it was just under $30. And I just placed the order for the Carter lift pump from Amazon for $115.

WWDiesel wrote:

Yes, I still have a couple of the *secondary fuel filter mounting brackets in stock or I can supply you with the complete kit to install a *secondary fuel filter & gauge.
(*Must have a lift pump installed)

I would love to place an order for the kit. Just lemme know what I need to do.

TKB4 wrote:

Sounds like you have a good plan to eliminate all the air in fuel possibilities as well as provide better filtration of fuel. The thermostat is not related to the problem unless the wiring sensor involved not the thermostat itself. If the older style Fuel filter head in place it needs to be changed anyway for fire protection etc and u will need the wiring connector too unless you live in warmer climate ( the only difference is for the heater element connector). Maybe the fuel head change will correct the problem till you get a convenient time to do the rest. Congrats on researching the problem here before you even asked for suggestions. Even when I am pretty sure I know what to do it helps my confidence tremendously to have other viewpoints .

I really want to do as much preventative maintenance/upgrades that I can reasonably afford to increase the longevity of the engine. I got this thing with only 55k miles from an old lady who had all the service records from the dealership she bought it from. It was a grocery getter. It does have the F37 TCU flash (written under the hood on service tag) but other than that I think it is bone stock. Seems like a pretty decent specimen for these rare CRDs and I would like to give her the respect she deserves.

I have very little experience working on/repairing vehicles (been driving a Honda most of my life and she never seemed to need anything from me), so reading this forum is a must for me. But I am actively trying to learn auto mechanics, and it seems like this Jeep has plenty of quirks (flaws) that need to be fixed before she's up to par so seems like a good vehicle to learn on.

Right now the plan is to:
1) install updated filter head
2) install lift pump
3) install WWDiesel's secondary filter kit
4) Load a tune from LOST onto the ECU
5) Install a Euro/Suncoast torque converter with SunCoast pre-F37 TCU flash. This is low priority for me, should it be?

I am DEFINITELY going to need some guidance about choosing and installing the proper flash when I'm done with the fuel system upgrades. I'm more concerned about fuel economy than extra power but none of the flashes are described as being focused around fuel economy. I know Yeti is the go-to man on this subject but I don't want to bother him until I've done some more reading and closer to flash time.

Thanks again, everyone. This is a wonderful community of extremely knowledgeable people.

TKB4 · **Posted:** Thu Mar 12, 2020 12:03 pm

Upgrading the torque converter is not a priority and may not even need to be done if you use a lower powered basic tune or continue with the f37.

You can unplug the MAF (mass air flow ssensor right now if you haven't already also know as the off road mod ORM) and that alone may well increase your fuel mileage 1-2 mpg. It also disables the electronic control of EGR . This ORM will trigger a CEL but you can use a yeti tune that disables this and in meantime you can plug it back in every once in a while to make sure another cause of light or read the codes through the OBD port. You can generally "drive around" the torque converter shudder its not that hard to do . Basically if its not actually shuddering its not causing potential damage to the transmission. I would change the trans fluid though if you haven't.

WWDiesel · **Posted:** Thu Mar 12, 2020 4:01 pm

ericg88 wrote:

WWDiesel wrote:

Yes, I still have a couple of the *secondary fuel filter mounting brackets in stock or I can supply you with the complete kit to install a *secondary fuel filter & gauge.
(*Must have a lift pump installed)

I would love to place an order for the kit. Just lemme know what I need to do.
Thanks again, everyone. This is a wonderful community of extremely knowledgeable people.

Sent you a PM and a email.
or
You can send me an email

ericg88 · **Joined:** Wed Apr 03, 2019 8:34 pm **Posts:** 16

Just to update, I installed the new filter head today and drove around to see if that solved it. Tripped limp mode in about 20 minutes. It kinda seems to go into limp mode when I come to a stop after going highway speeds for a while, like slowdowns in traffic or a red light after an exit. I'm going to install the lift pump tomorrow and hopefully solve the problem or find the diesel leak(s) that were air leaks.

I'm still not 100% sure how to do the wiring, a lot of the pictures in the guides were blurred out. Looks like you just run a power wire from pin #2 (ten pin connector) to pin #4 (4 pin connector) and then run a ground from the 4 pin connector to the grounding bolt?

If the code still trips after the lift pump I guess it's back to the wiring and then on to replacing sensors.

TKB4 · **Posted:** Sun Mar 15, 2020 1:33 pm

I don't know what pin to use I spliced into wire under passenger side back seat. No big deal but its usually referred to as Limp mode not safe mode although I think the manual somewhere calls safe mode when engine power/ fuel cutoff initiates from overheating. We definitely know what you mean or at least I do. I am sure others will answer the pin number soon. Way to get serious on getting to the bottom of this and putting in the work.

WWDiesel · **Posted:** Sun Mar 15, 2020 3:29 pm

I believe this covers it pretty well:
Link> http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?p=328862#p328862
Plenty of pictures

Sample:

flash7210 · **Posted:** Sun Mar 15, 2020 5:57 pm

One easy electrical test to try is:
1. clear the codes
2. disconnect the fuel rail pressure sensor
3. read codes again
4. if you get a code that IS NOT p0192, then it might actually be a bad sensor

ericg88 · **Joined:** Wed Apr 03, 2019 8:34 pm **Posts:** 16

I got the tank and harness pulled today. Started taking apart the loom. I'll add the wires, install the pump, and try to get everything put back together tomorrow. I see why everyone hates those quick connects so much. They had so much grime around the seals I'm surprised my fuel system isn't full of silt and sand.

The job has been easier than I expected so far, thanks to the excellent guides and advice from this forum. The clamp that holds the fuel lines up would most definitely have been broken in a rage if it weren't for the guide, and I managed to pop the quick connects easily using a small pair of channel locks.

flash7210 wrote:

One easy electrical test to try is:
1. clear the codes
2. disconnect the fuel rail pressure sensor
3. read codes again
4. if you get a code that IS NOT p0192, then it might actually be a bad sensor

I will try that as soon as I get everything put back together.

ericg88 · **Joined:** Wed Apr 03, 2019 8:34 pm **Posts:** 16

Update: Got the wiring harness wired and reinstalled yesterday. Plugged in the pump to test it and we're are all good.

BUT...

As I was looking at the pump I noticed it didn't have the same stickers as the ones I have seen online. The only sticker it had was a small oval sticker that said "Carter". I checked the box and it said "Made in China" on the bottom, but it does say P76148M on the box.

The only numbers I see on the actual pump are "6148BC" and below that "19339".

I really didn't want to install an incorrect pump, so I called Carter and got ahold of a tech rep. He said they do manufacture pumps in China and that this is the correct pump. I don't know why it says 6148BC instead of 71648M. The BC scares me but he said it's the same pump.

I went ahead and installed the pump in the tank but didn't have the time to finish getting the tank reinstalled. I didn't swap the fuel arm from the old unit because they looked identical to each other. The only way to get either arm in the exact same position as the previous unit would be to slightly bend it. I decided not to bend it and see what happens.

Hopefully the next update will be about a victory lap in a happy CRD.

WWDiesel · **Posted:** Tue Mar 17, 2020 1:00 pm

These are the part numbers I have on file:
In-tank lift pump
Mopar: 5143160AB
CARTER P76148M
AIRTEX E7181M
DCJ (P)52121447AD

This was the numbers on top of the last in tank pump I installed:
CARTER P76148M

P0192 and air in fuel head HELP

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