Posted on multiple forums for help because I'm loosing my mind lol.


Let me start with my truck and how this all started I have an

03 3500 srw 246,000 miles

Things I've done over the last 8 years

- Fass 150 Platinum (single filter)(6yrs ago)
- Aftermarket wastegate (6yrs ago)
- Smarty SP07 (7yrs ago)
- Fully built trans trq converter billet input,output, valve body, flex plate, upgraded electrics(6yrs ago)
- aftermarket intake (boost tube)(6yrs ago)
- K&N intake (8yrs ago)
- Solid 1 piece drive shaft with upgraded U joints no more center support bearing (2yrs ago)
- 5" turbo back stainless straight pipe (5yrs ago)
- Full gauges

my truck had a hard start issue for about 8 months. Went through all the cheap DIY fixes thinking it was a fuel delivery problem

- replaced rail pressure sensor
- put in high pressure relief valve block off
- pulled sending unit to verify I didn't have a blockage. (In the process knocked something loose because I no longer have a working fuel gauge... always empty lol)
- replaced all fuel lines from tank to fass to cp3 (old and dry)
- changed pre pump strainer and fass filter

Didnt solve it so I finally bit the bullet and took it to a local diesel shop that does some of thier own heavy equipment repairs the head mechanic is supposed to be a cummins guy so I took a chance figuring it was the injectors or the CP3 due to the mileage.

They looked at it and said my injectors were extremely worn why it was hard starting. Bought industrial injection +100s, Bosch connector tubes, and a high pressure rail with new sensor and relief valve and had them install them.They did the work following the torque procedure.

Called me saying it was ready to be picked up. Truck started right up 1/4 crank dont think it was ever that good. Left and noticed that it had no power.. ehh maybe it's the computer recalibrating..?.? Made it about 4min and noticed my rail pressure only got up to 6k.. then continued to drop till zero and the truck would starve for fuel and die. Would start right back up but wouldn't build pressure and just limp till it died again. Called the shop they said bring it right back.

They trouble shot it for a couple days... replaced a map sensor, Did a battery maintenance, used the smarty to bring it back to a stock tune (had been at lvl8 or 9 for 5yrs lol) called me back saying it was the cp3 failing. I was trying to save money at this point considering i just broke the bank on injectors, tubes, rail, and labor. The head mechanic said it was an easy swap and I could do it.

Limped the truck back to my driveway added an inline pressure gauge between the fass and the cp3 just to be sure (constant 18psi) and did a bucket test on the fass (150gph) to start eliminating possible faults in the fuel system. Everything checked out so I found a 30k mile cp3 from an 03 and replaced it in 0 degree Northern IL weather.

Excited that I might finally have my truck back after 2 months jumped in started right up (1/4 crank again YES!) Drove ok still a dog maybe this is stock. wow.. pressure built to 20k couple minutes only 6k... then 3k then 0.... ****. Died. Called the shop flipping out... *** man not the cp3. Get it back here I wont leave you hanging..

Limped it back to their shop -5 degrees died about 10 times until the batteries crapped out then I had it towed.
They trouble shot it for a couple days chasing wires, asked for my old cp3 to check the FCA, ohmed at 2.7 just like the new FCA did. Retorqued injectors/tubes checked lines for leaks. Had another mechanic come out with a more specialized engine/computer analyzer. Said it was my ECM.. the truck would run fine with full voltage at the FCA but then the voltage drops and so does the rail pressure. Mentioned it would drop to 1.2 amps then .9 then it would die. Get it home and have the ECM sent out.

Sick of just throwing parts at it I called SIA and talked to their technician that repairs cummins computers. Went through that book of history that I just typed he said that the FCA in communication with the rail pressure tells the ECM what voltage it needs, it's on at 2.6-4.6 volts. It would be the first computer that he has seen that failed in that manner but he would look at it if I wanted to send it in.... so here I sit with a broken truck lol

 

Wow, where to start . . .

Pre Injectors

Were any codes present prior to replacing the injectors?

You had a hard start issue for several months. Once it started, did it run OK? You didn't mention any power or smoking issues at that point.

Post Injectors

Are any codes present?

You mentioned "Full gauges". When you left the shop the first time, how much pressure was the Turbo putting out when running down the road and "noticed that it had no power"? Do you still have your original wastegate (for possible testing purposes)? Are your boost tubes all tight?

Looking at your voltage drop at the FCA, there were some trucks experiencing low voltage signal wiring that had the insulation rubbed through and grounding the signal voltage. This affected several systems IIRC. The place to look is behind the AC compressor for a small bundle of wires. No cost to you if you look for it. If you find worn insulation, simple electrical tape would give you a test to see if that was the issue. Either way, if you find worn insulation it needs to be repaired properly.

Good Luck. I loved my '03 when I had it.
Back to morning brew . . .

 

Pre injectors - no codes that I remember. Ran beautiful once started.
Took it on a trip over Thanksgiving to my fiance's parents in Missouri (about 400miles). Cruise control set at 75 rumning great then about halfway there loss of power look behind me entire Expressway is fogged in white smoke. Pull to the shoulder truck dies start it back up major white smoke and a loud injector knock . Limp it to the next exit and found a place to park it continued to Missouri for Thanksgiving. Came back to it 2 days later on the way back started right up brought it to a diesel shop there owner looked over it couldn't find anything wrong, coolant good, built to temp and held, injectors firing properly, sounded great.. limp it 200miles home was probably a "stuck" injector. Kept it under 65 and low boost just in case all the way home... ran perfect (got 24mpg by the way lmao). Took it to the shop that replaced the injectors after that.

- Post injectors.. I know they got a map sensor code why they replaced it. I can ask on others. As well as check tomorrow when I'm working on it. Boost tube(intake), wastegate have all been on there and working great for over 6yrs. Couldn't build boost because couldn't build fuel pressure or get the rpms up. Literally nothing past 1/8 a pedal once it starts doing this.

 

Ok worked on it this morning.

- Ran truck till loss of pressure and died no FCA click under hood.

- Bypassed Fass 150 ran straight from tank to CP3, unplugged electrical connection at the FASS. Started truck same problem idled till loss of pressure then died, no FCA click after stall.

- checked wires behind ac compressor all looms look to be decent no burn or cracked areas.

- Codes present after testing today

P0251 CP3 pump regulator control

P2509 powerdown data lost error

- Remanufactured injectors

- No abnormal smoke



Is ECM failure a possibility?

 

Firstly, I'm glad you got away with a stuck injector and didn't wreck the engine. It killed my 2003, and I had to adapt to a 2006.

I'm no expert on this aspect of the truck-but I have read some stuff when I was troubleshooting a no start condition.

Question: How quickly do you loose fuel pressure? My understanding is that if you disconnect the FCA connector, the fuel rail should default to max pressure-26k or so. The truck will sound a bit like a mechanically injected truck, but should run ok. If you do this and idle the truck does it maintain fuel pressure or die? Note: It's not great for the truck so don't do this for an EXTENDED period. If it still dies then you have isolated the ECM-FCA drive from being the problem. If it doesn't die-well maybe you're onto something. REALLY RARE though.

Also, I'm not sure if you tried this, but the FCA is supposed to rattle when you remove and shake it. Have you tried this quick/dirty test?

With the FCA disconnected, if it looses fuel pressure, I'd still suspect a low pressure fuel delivery issue or a CP3 issue, especially with new injectors, a blocked bypass, starts great, and no smoke out the back when it starts misbehaving.

You could easily monitor the 5V from the ECM at the time your fuel pressure is dying off as well...This would prove/eliminate the wire insulation idea, which is good suspect. I might check the battery connections, 12V ECM feeds and grounds also-make sure they are good and corrosion free.

Would you have any way to see the commanded rail pressure vs the actual rail pressure? Like a HP Tuners, or EFI live setup?

This is the challenge with diesels...trying to 'see' into the issue is very difficult. Certainly harder than a gasser.

If you have some time, you might want to check tighten the tubes-it's easy to make an error on the tube nut because of the shape of the head. Hard to believe that's it, but if one starts leaking you'd never know it except it'll bleed your rail pressure.




Chay

 

Have done alot in the last week and a half. Downloaded the manual to troubleshoot grounds, Connector diagrams for the ECM, pcm, fca. Tested batteries connected and not connected for voltage differences. Unplugged ECM and resistance tested power supply lines and grounds. While diagnosing unplugged fca while truck was running no change in fuel pressure stayed at 6k. Since it was only $100 bought a new Bosch FCA and installed it.. same thing no change when unplugged while running. Back to wire testing, finally today said screw it and sent out the ECM.