JT 3.0 Diesel with ongoing P2635 Error

[JT_RHINO]

Hey JT Diesel fans...

Hoping to document this issue for anyone else that may experience. If this already has a thread and you see please loop this in.

First off...love my 21' JT EcoD. I really do. I've been a Jeep fan for a long time...owned multiple Jeep Cherokee Classics and Wranglers over the years and alway dreamed of the day they'd make one with a diesel. The JT added "truck" capability is basically "perfect" for what I wanted.

Picked it up with 21K (currently 37K and counting) from a dealer with 35's, winch, etc and all the recalls done (HPFP, axle)...
Fast forward to 35K and one cold am the auto-start stopped after a few min with the P2635 code.

Raw code: 2635
ECU: Engine control unit
Status: Confirmed
Fuel pump (FP) A - low flow/performance problem

I cleared to see if it was related to the cold (-5) and it returned a day or so later and has continued to show up sporadically since, sometimes daily but never more than once in a day even with multiple uses. The cold hasn't subsided but has ranged from -13 to 40 during this time.

I took it in to a local dealer for investigation and after having it for a week came back with no ideas or root cause. They wanted to change the filter but I opted not to as I was only 4-5k into a new one. Charged me for diagnostic time which was frustrating as I have a warranty ( Certified pre-owned) - apparently a loop hole since nothing was determined to be wrong as they could not duplicate, even though they claimed to have started multiple times and taken for a 45 min drive.
They did update the ECM.
I took home and the next day it threw the code during warmup startup.
I called dealer and let them know but informed them I'm not bringing back to pay for more diagnostic work to come up empty.
I started keeping a log of the error and would clear and drive (nothing super apparently obvious as far as performance - I don't drive it hard and with the snow /weather it was uncertain if the MPG dipping occasionally to 18.x from 20-22 in the summer has anything to do with it.

I eventually decided to have the fuel filter changed out (just in case) after the error continuing to show up every other day and for a week every day at least once, sometimes at first start of day and sometimes the later start (school drop-off and pickup 40-min/each way). I had a Mopar filter put in at the dealer (ouch) - (was using Doc Diesel and work done at respectable local mechanic for previous - don't have a garage to use). Went 2 days (-13F and 5F) with no issue and then the code came back while driving (less common case - only 3 times out of prob 16) on the 3rd day.

So now...at a loss.

1. Dealer has claimed to have sent my log of error codes to a Engineering rep for some help but not holding my breath.
2. I did speak with Green Diesel Engineering about their ECM flash as an option and they seemed to think the code is not related to the HPFP (super knowledgeable and helpful btw). I was looking at flashing to improve the engine /trans efficiency and operation and may still do that, just hesitant at the moment in the event the dealership gets back o me.

I am hoping to get it figured out as I truly love this Jeep....and from all my research this EcoDiesel motor/transmission combo is pretty decent and should be pretty dependable. (Even more so without the EPA crap - but that's another thread....)

Will post back as I navigate this frustrating issue.

-M

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[JTdiRtyD]

First off, are you running any fuel additives? Specifically anything with an anti-gel?

Second, mpg decrease in the winter is normal because of winter blend fuel.

 

[JT_RHINO]

Hey Wes..thanks for the response!
I didn't think about the winter blend efficiency...good point.
I had read a bunch of threads about the CP4 pump and lubricity issues etc,... so I as a precaution was using HotShots EDT (no noticeable change in performance) for a bit and the LX4 lubricity (until it froze in the bottle - which made me concerned about what is happening in the tank/filter - it's a small amount but might not be helping on cold days) - I then switched over to Howes which I used to run in my 7.3 Powerstoke. I have since stopped using any additives since I know the pumps are on the winter blend and after talking with some Green Diesel (GDE) guys. In conversation I had asked them is they used or preferred anything and the said no, they don't run anything in their diesels.

I will say since having swapped the filter and cutting the use of anything for additives I have only had the CIL pop once while driving in the last 5 days - 4 days of driving and auto-starts at temps of 5, -13, 5 and 30 this am. Oddly, my MPG has seemingly gone up almost 2mpg since the filter change as well...which is strange. Wondering if there was something there. Either way...I will be keep on recording what i run into and share what I find out.

 

[RandyP111]

Hey JT Diesel fans...

Hoping to document this issue for anyone else that may experience. If this already has a thread and you see please loop this in.

First off...love my 21' JT EcoD. I really do. I've been a Jeep fan for a long time...owned multiple Jeep Cherokee Classics and Wranglers over the years and alway dreamed of the day they'd make one with a diesel. The JT added "truck" capability is basically "perfect" for what I wanted.

Picked it up with 21K (currently 37K and counting) from a dealer with 35's, winch, etc and all the recalls done (HPFP, axle)...
Fast forward to 35K and one cold am the auto-start stopped after a few min with the P2635 code.

Raw code: 2635
ECU: Engine control unit
Status: Confirmed
Fuel pump (FP) A - low flow/performance problem

I cleared to see if it was related to the cold (-5) and it returned a day or so later and has continued to show up sporadically since, sometimes daily but never more than once in a day even with multiple uses. The cold hasn't subsided but has ranged from -13 to 40 during this time.

I took it in to a local dealer for investigation and after having it for a week came back with no ideas or root cause. They wanted to change the filter but I opted not to as I was only 4-5k into a new one. Charged me for diagnostic time which was frustrating as I have a warranty ( Certified pre-owned) - apparently a loop hole since nothing was determined to be wrong as they could not duplicate, even though they claimed to have started multiple times and taken for a 45 min drive.
They did update the ECM.
I took home and the next day it threw the code during warmup startup.
I called dealer and let them know but informed them I'm not bringing back to pay for more diagnostic work to come up empty.
I started keeping a log of the error and would clear and drive (nothing super apparently obvious as far as performance - I don't drive it hard and with the snow /weather it was uncertain if the MPG dipping occasionally to 18.x from 20-22 in the summer has anything to do with it.

I eventually decided to have the fuel filter changed out (just in case) after the error continuing to show up every other day and for a week every day at least once, sometimes at first start of day and sometimes the later start (school drop-off and pickup 40-min/each way). I had a Mopar filter put in at the dealer (ouch) - (was using Doc Diesel and work done at respectable local mechanic for previous - don't have a garage to use). Went 2 days (-13F and 5F) with no issue and then the code came back while driving (less common case - only 3 times out of prob 16) on the 3rd day.

So now...at a loss.

1. Dealer has claimed to have sent my log of error codes to a Engineering rep for some help but not holding my breath.
2. I did speak with Green Diesel Engineering about their ECM flash as an option and they seemed to think the code is not related to the HPFP (super knowledgeable and helpful btw). I was looking at flashing to improve the engine /trans efficiency and operation and may still do that, just hesitant at the moment in the event the dealership gets back o me.

I am hoping to get it figured out as I truly love this Jeep....and from all my research this EcoDiesel motor/transmission combo is pretty decent and should be pretty dependable. (Even more so without the EPA crap - but that's another thread....)

Will post back as I navigate this frustrating issue.

-M

Need to ask you...do you park on an uphill grade? I have detected this code, and cel on my 2022 ecodiesel gladiator quite a few times and it is nearly always due to a grade, parked overnight. When I park on an uphill grade, I do several non start priming cycles to pressurize the low pressure (from fuel tank) side of the fuel system before normal ignition on brake pedal pressed start. It does not happen if primed. There are low pressure problems with the fuel system as well as the more publicized HPFP problems. This priming is like what you do when you change the fuel filter before starting the engine. Hope this helps.

 

[JTdiRtyD]

Has this all been filling up from the same station? My initial thoughts are maybe you're starting to see some gelling at those cold temps from bad fuel, or possibly water in the fuel. I've had some strange fueling issues with my BMW diesel while out in Idaho from bad fuel.

Otherwise what RandyP111 stated sounds possible as well.


Check this thread out regarding additives. The original video post is a good watch (have to watch on youtube), but theres another one a few posts down regarding anti-gel.

https://www.jeepgladiatorforum.com/forum/threads/diesel-engine-additives-test.89196/

 

[JT_RHINO]

Need to ask you...do you park on an uphill grade? I have detected this code, and cel on my 2022 ecodiesel gladiator quite a few times and it is nearly always due to a grade, parked overnight. When I park on an uphill grade, I do several non start priming cycles to pressurize the low pressure (from fuel tank) side of the fuel system before normal ignition on brake pedal pressed start. It does not happen if primed. There are low pressure problems with the fuel system as well as the more publicized HPFP problems. This priming is like what you do when you change the fuel filter before starting the engine. Hope this helps.

Thx Lance! I do park on a slight grade (guessing 10% or less but sideways....I had thought about the priming option - kinda unfortunate to have to walk across the road where i park and do that on cold am's - seems that shouldn't have to be the case. I haven't heard of low pressure issues so thanks for sharing, what you stated makes sense if it slowly depressurized due to an elevated angle. I will be consistent on which way I park for the next few weeks and alternate...see if I notice any particular pattern. I think that's the hard part so far...finding a pattern. LOL.
Appreciate the feedback.

 

[JT_RHINO]

Has this all been filling up from the same station? My initial thoughts are maybe you're starting to see some gelling at those cold temps from bad fuel, or possibly water in the fuel. I've had some strange fueling issues with my BMW diesel while out in Idaho from bad fuel.

Otherwise what RandyP111 stated sounds possible as well.


Check this thread out regarding additives. The original video post is a good watch (have to watch on youtube), but theres another one a few posts down regarding anti-gel.

https://www.jeepgladiatorforum.com/forum/threads/diesel-engine-additives-test.89196/

Good point on fuel...I read a few horror stories on this forum and some other RAM EcoD threads with water etc.....I generally try to stay consistent with where I get fuel and try to use Truck stations, etc that have a lot of use. Currently use a Citgo truck station with a lot of traffic and a local Mobil which has the least expensive diesel around - relatively new and frequented by most of the construction / plow guys in the area. I have a pretty set route pattern so I may try to use just one for a bit and then switch up and see if I notice a pattern. I usually try to keep the tank above the 3/8 mark as general principle. I'll check out the vid/link on additives... Thx!

 

[nanook12]

Well I hope you are preheating that engine at -13! Run an anti-gel and fuel lubricator. I use Kleen white bottle and 2 cycle oil for lube. You may be dealing with a non winter weight fuel problem

 

[CrazyCooter]

Well I hope you are preheating that engine at -13! Run an anti-gel and fuel lubricator. I use Kleen white bottle and 2 cycle oil for lube. You may be dealing with a non winter weight fuel problem

Preheat with external help?

I don't believe in idling to reach operating temp. I will start and wait long for things to get flowing and happy, but begin driving in short order because idling is generally just washing unburned fuel down the cylinder walls past the rings. I'd rather warm up under light loads while driving.

 

[JT_RHINO]

Well I hope you are preheating that engine at -13! Run an anti-gel and fuel lubricator. I use Kleen white bottle and 2 cycle oil for lube. You may be dealing with a non winter weight fuel problem

Nanook12...thx for response. Amazingly...she has started right up without heater block in the latest string of cold temps. My older 7.3 back in the day would never have started. Had to run a block heater for temps under 20F. Diesels have come a long way! I have opted to run nothing for additives since the last fuel filter change. So far only one CEL in the last 8 days ... go figure. I'm starting to wonder...

 

[Nobody]

I’ve had the same problems with CEL and similar codes. I think it’s the same one but can’t remember it exactly. The truck would pop the code sometimes right away after starting or after driving for 30-40 minutes (highway). I started by draining the filter at the little drain valve. That helped cut down the frequency of how often the code was CEL was popping up. Then I stopped using additives. Then I ended up changing the filter. Haven’t had one in several months. I think all these additives are really for the older diesels and older fuel pumps. But here don’t need them. Just my opinion. Kinda like older cars needed the lead additive when leaded gas went away. Full disclosure I have used additives the last few fill ups for winter temperatures purposes (CO Rockies) and yes my MPG has taken a hit of about 3-5 MPG.

 

[JT_RHINO]

I’ve had the same problems with CEL and similar codes. I think it’s the same one but can’t remember it exactly. The truck would pop the code sometimes right away after starting or after driving for 30-40 minutes (highway). I started by draining the filter at the little drain valve. That helped cut down the frequency of how often the code was CEL was popping up. Then I stopped using additives. Then I ended up changing the filter. Haven’t had one in several months. I think all these additives are really for the older diesels and older fuel pumps. But here don’t need them. Just my opinion. Kinda like older cars needed the lead additive when leaded gas went away. Full disclosure I have used additives the last few fill ups for winter temperatures purposes (CO Rockies) and yes my MPG has taken a hit of about 3-5 MPG.

Bob - thx for sharing! I leaning in the same direction of not running any unless absolutely needed and typically here in VT, temps like -13 to 2F are not the norm for extended periods of time.

On a side note, I did come across an interesting article that points to the real issues with HPFP pump failures due to design being susceptible to damage from aeration BECAUSE air (and water ) are especially problematic for the CP4.2 pump. It's a good read:

"With its ultra-tight tolerances, the CP4.2 does not tolerate anything other than diesel fuel very well. But which unwanted contaminant is most common? Air. That’s right, aeration is the number one killer of these pumps. Whether it be from lack of maintenance, running the truck out of fuel, improper fuel filter installation, or not allowing the fuel system to properly prime after a filter change, nine times out of 10 this is what takes out the CP4.2"

https://www.dieselworldmag.com/diesel-technology/cp4-2-fuel-pump/

There is also an design upgrade to the CP4.2 pump called the CPx from RCD ...seems to address the atomic failure issue and redirects debris back to tank vs. fuel lines etc. I think I will prob upgrade to this once I'm out of warranty.

Thanks for sharing Bob

 

[JT_RHINO]

Posting back...

Since the filter change (1/29) ...today is 2/21... I've had far less CEL errors, 3 to date - all after a successful remote start - usually within the first few miles of driving. I pullover when convenient and reset and error does not return (usually a 80 mile trip). The temps have been below 10F on average.

I have not been using any additives any more.

A this point I'm going to continue to monitor.

A GDE tune is planned in the next month.
WIll post after after and when we get into warmer months.

-M

 

[Vtur]

Factory or aftermarket fuel filter?

 

[JT_RHINO]

Factory or aftermarket fuel filter?

I was running a Doc's diesel filter initially, Mopar on the change - had about 5k miles on Doc's before issues started. I was running additives in my tank which on review may have been over supplemented. Not sure if that was contributing. in addition i noticed the Lubricity additive was frozen in my truck when the cold hit VT where I live and it hasn't left - still averaging 10F.

At this point a new Mopar filter and 0 additives is better than previous.

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