Cat 308E2 CR SB Code 1239-1

[Pete w]

Serial# FJX00221
Good morning Ladies and Gents,
Machine has had this issue for a couple months. Operator would complain that it would start beeping and saying shut down engine safely and de-rate. Shut off and restart and it would be fine the rest of the day. Each time i went out i could not replicate and there were no logged codes. Issue became more and more frequent to the point we are now. Typically when you start it and let it idle to warm up it will throw the error and de-rate. Turn it off and right back on and throttle all the way up and it runs fine no issues. While its beeping it throws active event 1239-1.
Unit was on its way to another job literally passing cat so i had the driver stop by and have them hook up to it and see what they said. They told me it needed injectors. Adamant that is the common problem with these engines. Fair enough. Ordered and replaced the next day as well as the fuel filters. Same problem. removed all the lines and blew everything out to verify no blockages. Checked the filter head and fittings. Nothing. Replaced the low pressure fuel pump to rule out. No change. Fuel seems clean.No contamination to note.
Fuel rail pressure seems to be reading normal although i do not know what the ratings are supposed to be at with what throttle position. Full throttle its showing 14,700-15,230 PSI Idles around 6,200 PSI.
Talked to Cat again and they seemed stumped and said that i may need a new fuel rail since the pressure sensor is not serviceable and is apart of the rail. And a new high pressure pump. Im not into throwing parts at it playing a guessing game. Ive seen other posts on here regarding this code and it seemed they had blockages or contamination. Nothing like my issue.
Impart your wisdom on me!

 

[Chrisso]

They told me it needed injectors. Adamant that is the common problem with these engines.

Dirty fuel or water in the fuel does cause 90% of problems that lead to seeing this code. It's not the injector's fault.

I see parts replaced but no pressure checking of the low pressure fuel system in the above. Also check the little transfer pump is getting 12 volts. No time here to look deeper and give a detailed reply but hopefully someone will be along soon with troubleshooting procedures and fuel pressure specs. Does this fuel system have a little pressure reducing valve that reduces pressure from 10ish psi to 1-2 psi? If so I'd throw one of those at it. I'll check tonight unless someone beats me to it.

For a problem so hard to replicate I'd be inclined to hook up an inline pressure gauge to the low pressure side of the fuel system. If the pressure remains constant when the next 1239-1 code displays, only then would I look into the high pressure (expensive) side of the fuel system.

 

[Nige]

A mentor of mine opined many years ago - "When starting to diagnose either fuel or hydraulic system problems, start from the same point that the fluid starts its journey - the tank." Wise words.

To the OP. When was the last time water and sediment was drained from the tank.? The procedure will be right there in your O&M Manual. You know - the one that nobody ever reads............

This sort of problem is typical of smaller machines that tend to get filled up from jerry cans or similar rather than from a fuel bowser. Unless someone pays attention to keeping the containers clean all the contamination ends up in the tank.

 

[heymccall]

For the 1G-7206, did you change it?
If so, was a genuine Caterpillar part?

I ask because if you use a cellulose type filter (like a Fram G1), they are not compatible with diesel. That "filter" is actually a screen element.

 

[Chrisso]

Does this fuel system have a little pressure reducing valve that reduces pressure from 10ish psi to 1-2 psi?

To answer my own question, no it doesn't. That little transfer pump (#7 in Heymccall's post) provides your 1-2 psi. No 10ish psi to speak of in the low pressure side. My advice still stands regarding hooking up a pressure gauge inline, but to do it you'll need to tee into the low side and run a proper test hose to a gauge in/near the cab. If you make the fuel travel 'in-line' all the way to the cab and back you'll loose the 1-2 psi in resistance alone at those low pressures due to the distance the fuel has to travel. You'll need a 0-20 psi gauge at best to measure it accurately.

Another thing I would do before touching the high pressure side is to thoroughly inspect the engine harness. Wiggle it in every accessible location with engine running to see if you can bring on the 1239-1 event. There's a million sensors in that harness.

Please let us know what you find.

 

[Pete w]

A mentor of mine opined many years ago - "When starting to diagnose either fuel or hydraulic system problems, start from the same point that the fluid starts its journey - the tank." Wise words.

To the OP. When was the last time water and sediment was drained from the tank.? The procedure will be right there in your O&M Manual. You know - the one that nobody ever reads............

This sort of problem is typical of smaller machines that tend to get filled up from jerry cans or similar rather than from a fuel bowser. Unless someone pays attention to keeping the containers clean all the contamination ends up in the tank.

I did attempt to drain the bottom of the tank, plugged up. Ive always been a big proponent in draining off the bottom of the tanks. Drove a wire through the shut off and then blew with air. I was getting air through but no fuel. Will have to dig deeper when i get another chance.
As it pertains to re-fueling, we use no jerry cans or anything like that. the smallest type tanks we use are fuel transfer tanks in the back of the foreman's trucks that are filtered. But typically we have large fuel tanks on the job for refueling. Not to say that contamination couldn't still occur but it would be pretty minimal.

 

[Pete w]

For the 1G-7206, did you change it?
If so, was a genuine Caterpillar part?

I ask because if you use a cellulose type filter (like a Fram G1), they are not compatible with diesel. That "filter" is actually a screen element. View attachment 300105

Replaced with Cat.

 

[Pete w]

To answer my own question, no it doesn't. That little transfer pump (#7 in Heymccall's post) provides your 1-2 psi. No 10ish psi to speak of in the low pressure side. My advice still stands regarding hooking up a pressure gauge inline, but to do it you'll need to tee into the low side and run a proper test hose to a gauge in/near the cab. If you make the fuel travel 'in-line' all the way to the cab and back you'll loose the 1-2 psi in resistance alone at those low pressures due to the distance the fuel has to travel. You'll need a 0-20 psi gauge at best to measure it accurately.

Another thing I would do before touching the high pressure side is to thoroughly inspect the engine harness. Wiggle it in every accessible location with engine running to see if you can bring on the 1239-1 event. There's a million sensors in that harness.

Please let us know what you find.

It'll be tough given that this is low pressure hose and barb fittings. I have a kit but only for high pressure stuff so illl have to try and rig something. Harness looked good with no rubs or anything concerning. I had most of it off and unplugged to do the injectors. I also focused on the pressure sensor harness as well.
There is an IPR valve on the high pressure pump that could be a culprit, but given its electronically controlled i figured that would come with its own set of codes and symptoms.

 

[Nige]

I did attempt to drain the bottom of the tank, plugged up. Ive always been a big proponent in draining off the bottom of the tanks. Drove a wire through the shut off and then blew with air. I was getting air through but no fuel. Will have to dig deeper when i get another chance.

That’s worrying that you can get nothing out of the drain. It means that something somewhere is full of sh1t. I suggest that needs to be attended to as priority #1.

Back to the subject of the engine wiring harness as mentioned above. A bit more digging revealed service documentation that these harnesses are known to fail because they are very tightly wrapped around the engine and wires can fail in those tight bends. It appears as though the best way to identify a suspect harness is to subject it to the “pull test” while the engine is running and see if it throws the Code you have been getting.

 

[Nige]

Having thought more about it I am of the opinion that, after attending to the tank drain and removing whatever crud there is in there, you ought to spend a fair amount of time "testing" the engine harness because potentially you are in for some large purchases if you go down the replacement of the HP pump/fuel rail route with no guarantee of fixing the problem.

 

[Pete w]

Had a few more minutes with this unit to try a hair brained idea i had while on the job the other day. I didn't have long so i removed the line from the tank pick up tube. inserted a barb and ran a hose directly into the top of the tank to by pass any possible contamination on the bottom of the tank. bled the air out and tested....same issue.
Job just finished and unit was dropped at CAT per boss mans request given they had given us the initial diagnoses. I will update when i have more info.

 

[Pete w]

So Cat is worthless. They spent "3 hours" diagnosing. Highly doubtful. To say that my sensor in the fuel rail was indeed bad. Need a new rail. Told them to go ahead and install one, that way if that was just a guess it would go back on them. Part was ordered and supposed to be in next day....3 days later. nothing. Couldnt wait any more. picked up the unit again and put the rail on myself (they "lost" the part). Same issue...Called service, they are dumbfounded saying the tested the harness and all and that had to be the issue. They call back a few minutes later to inform me that the only other issues is could be is the suction control valve or the main wiring harness. To which i replied "great, your telling me you have no idea and you've been throwing parts at it from the start. Something i wanted to avoid in the first place and anyone with half a brain could do"
Replaced the control valve, nothing. Replaced the harness. fixed. Literally replaced every component it could be and of course it was the last thing. They swear up and down the harness was tested and ohmed correctly with no issues. All this to say that like every other dealer out there Cat has become worthless and of little help. Spent a lot of time and money to avoid throwing parts at the thing and thats exactly what Cat did.
If you end up having this as a persistent code. Good luck. Its a generic code that could mean an issue with: Injectors, fuel rail pressure sensor, low pressure fuel pump, fuel restriction in the tank or lines, suction control valve, or engine wiring harness. Start with fuel delivery and then test your sensors and harness for high resistance or opens. I was sure it wasnt any sensors as i was able to see all my live readings with no significant changes in pressures. Cat said otherwise. What do i know? I shook everything down and wiggled all my connectors. Looked over my old harness and seen no abrasions, cuts, rubs, corrosion, nothing. At the time i didnt have access to a wiring diagram to test from the ECM to the connector ends. I hope this helps someone down the line.

 

[Chrisso]

And... if you're going to throw parts at it, at least do it in a logical way. Throwing injectors at it = not logical. Throwing a harness at it (when these harnesses are 'known' to fail) = logical. Can't be that hard.

 

[Pete w]

Agreed. Trusted Cat had further capabilities to hone in on the issue than i did. Obviously not. They apparently like to work backwards (not surprising) throw the most expensive parts at it and go from there, charging as much as possible...