1995 Chevy 6.5 TD. I have been having problems with this truck for Months. Have taken it to the shop and have had no luck at all. Truck spits and sputters and sometimes almost dies and then keeps running. Most of the time it goes into limp mode and DTC 18 always comes up, 17 will come up half of the time and 35 once in a while.

I have searched the web and the forums and have done everything I can to it, with no luck.

I know these codes come back to the IP and the optic sensor.

I have done the following to truck.

1. Replaced IP with rebuilt one, same codes. Returned IP and got exchange still same codes.
2. New sending unit, removed sock and installed inline filter.
3. New fuel lines, both feed lines and return lines, from the tank to engine.
4. New filter in ffm. also new screen.
5. New orings in FFM.
6. Installed Feed the Beast Kit in FFM and 3/8" line to IP.
7. New optic sensor noise filter. Also tried it without optic sensor noise filter and ferrite cores.
8. Checked all wiring and cannot find anything wrong with wires or connections.
9. Cleaned all grounds and replaced some with new.
10. Added extra ground wires.
11. New PMD, relocated PMD.
12. Timed IP with gmtd scantech. tried timing at about .75 to 1.50
13. new lift pump and modified ops relay

I am sure I have done a few more things but can't think of them right now.

Anyone has any ideas on what I am missing here. Could I still have a bad IP, Could it be in my PCM. Is there anyway to test the optic sensor wiring.

Looking for some new ideas as I do not know what to try next.

 

I have no experience with the 95s but if i had to guess id say ecu computer. But thats a shot in the dark as i didnt have my 6.5 long enough to experience problems. Im sure racer 55 will chime in in the morning and have some answers good luck and dont sell it!

 

If it has an aftermarket CPS it could be contributing to the codes-AC Delco ONLY.

DTC 17 - High Resolution Circuit Fault
DTC 18 - Pump Cam Reference Pulse Error
DTC 35 - Injection Pulse Width Error (Time Short)

What shape was the IP harness in under the intake-rodents like to snack on the wiring under there?

Where is the IP/PMD harness ground fastened?

Have you tried grounding the PMD heatsink-some trucks seem to require that?

Have you replaced the IP return line with clear diesel rated line and looked for bubbles?
With an all new fuel system air should not be present but can also contribute to the codes you have?

Also note that fuel filters can not be removed and re-installed,once taken out they must be replaced because the O-ring deforms and will not properly seal.

 

Not sure what cps is in it, I ordered an ac delco cps and will go ahead and replace, just to make sure it is good.

IP harness was in great shape. IP ground is attached to IP.

Heatsink is grounded to Battery negative terminal. Have tried it grounded and not grounded.

Have clear line from return on FFM to return line and from pump to return line. No air in fuel.

new filter that has not been removed.

 

Got new ac delco cps installed and truck is still throwing dtc 18 all the time. Beginning to think I may have to try changing the pcm. any one have any other ideas on what may be wrong.

 

I would remove the OS noise filter and put the ferrite core back and try again.

Also put a call into the IP rebuilder and ask their thoughts on the code 18,could be a faulty OS?

have you run any alternative fuels through the IP,like waste oil?
If the color of the fuel is not almost clear it will affect the OS a lot.

 

will try ferrite core again.
have not run any alternative fuels at all. have had tank off and drained while removing sock. fresh fuel put back in.

 

Does your ip and ecm match? From my understanding 94's had 2 different ip if, for some reason, you have the wrong ip or ecm itll have the same issues. I had those same codes with my 94 because someone put an ecm out of a 95 in it thinking it was all the same.

 

Tried ferrite core again, still throwing codes. original pcm as far as I know, will check numbers on pump but pretty sure it is right one. Will contact rebuilder about codes. Looking at either another pmd a new pump or pcm.

 

I am encountering this issue i was wondering if you ever resolved it? I know its a little late, but i hope you know