I have a 1994 chevy k2500 6.5 diesel an when I drive it the motor randomally cuts out i have replaced the PMD an relocated it behind the bumper an everything but the problem didn't become solved the service throttle soon light comes on an it runs really rough if it restarts but if you let it sit until it's completely cold It'll restart like nothing happened an run for like 6 to 7 hours then it'll die again or if i go into the store an come back out the glow plug light will not come on an it won't start I'm getting fuel all my grounds are completely clean new glow plug relay as well I'm so lost somebody told me it could the PCM but I don't know help me please!!!

 

Also I've now noticed that when this happens I have no lift pump an it occurs a lot more often I put a scanner on the PMD to check it because I know it's possible to get a bad part but it's doing good everybody keeps telling me to look into the ECM but when they go it's at random not run then die then run again correct me if I'm wrong but I don't think that's it but I can't think of anything else :/

 

I suspect your Fuel Heater is shortening out internally and temporarily disabling the ECM, GP and LP circuits in the process so hard start, no start is par for the course..
Take note of the ambient temps when it occurs. If its near 45°F, the self regulating fuel heater may activate to preheat the fuel before it passes through the dual stage filter element. Because its self regulating unit, it only needs power supply thats provided by piggy backing the GPs ignition (switch) circuit. It doesnt communicate, isnt monitor'd by nor controlled by the PCM in any way..
It common for aging fuel heaters internal circuitry to work fine but the heating element itself to short out internally..

It wont necessarily blow any fuse(s) initially either. As the fuel heater malfunctions and backfeeds 12vts back throughout the system (shared grounds) it momentarily trips the PCM's internal circuit breaker(s) disabling that component(s).. You may also notice the WTS and WIF lamps flickering and/or fading "ON" and "OFF" randomly.
The PCM is made up of a processor ('puter) thats extremely sensitive to the slightest power fluctuations, where talking milliohms (why its so important to thoroughly inspect, clean grounds and the batteries are fully charged) so inorder to switch most 12vt or 5vt components "ON" or "OFF" as necessary, the PCM employees multiple quad drivers. Quad drivers function much as the name implies, it "drives" (switches) 4 components, 3 if said components can set DTCs. Its those internal circuit breakers that makes the PCM pretty robust component..
Because all of these quad drivers have their own protected circuit but often work in tandum with other quad drivers, "input information has an interrelation to more than one output, therefore, if one or more input failed it could effect more than one systems operation."
I know, alot of techno mumbo jumbo that I still dont fully understand yet but were working on it. Hard to learn about it when much of it is considered proprietary.. Just trying to connect some of the dots for you....


Check your ECM1 and ECMB fuses too, fact check them all..

Attached several diagnostic aids..
NOTE about the Fuel Pump Relay Cirrcuit Diagnosis. On '94 models, the DLC's "Fuel Pump Test Terminal" is "G," not "F" as indicated (for '95 OBD1 models)


If you discover the Fuel Heater is faulty, you can unplug it temporarily BUT if your exposed to freezing temps on a regular basis, I would reccommend it be replaced asap.
IIRC, rockauto[dot]com has fully assembled ready to drop in OEM FFM for @ $140.00, far less than what the stealerships want for the fuel heater alone....



Good Luck

 

I should mention that repeated "tripping" of PCM internal circuit breakers can damage the PCM. Much like a house 20amp circuit breaker thats trip'd repeatedly may damage the circuit breaker so its no longer able to function properly or power up the new device its intended to drive once the repair and/or replacement is made.
Thats why you shouldn't ignore the SES lamp.

Make any sense to ya?

 

Well after replacing the ECM 3 days ago an it dieing on me everyday I also noticed when it got warm outside she wouldn't start once again no glow plug light or service throttle soon light so I took it to a diesel shop an they have yet to give me any info on it I'm hoping it's a simple fix I've replaced a lot an have a lot into it if it's a big problem such as the injector pump I'll lose my head I've got $1400 into it as it is

 

Hopefully the shop knows 6.5 diesels. You may want to ask.

There are a lot of diesel shops that do not know these vehicles. One of the local shops just starts swapping parts. One truck they could not figure out anymore parts to swap, so they made it into a mechanical IP - Not a bad idea anyway.

That is also the same shop that told me I could have issues by running AC Delco 60G glow plugs because that is not what the vehicle had originally. I wonder if they think the same about the old PMD's? Actually I had my best longevity with the original PMD's in the original location.

But it is much easier to replace them in the front bumper

There is a line between how much you want to pay a shop to do the diagnostics or just replace parts til they get it right. Sometimes when you are paying somebody the big bucks, it is cheaper to just throw parts at it. It may take as much money for them to diagnose some parts as it would to just change the part

 

Well after spending $800 at the shop we figured out that it was the chip that is plugged into the ECM this had a high performance chip in and it shorted out replaced it and it's been running for about 2 weeks without a hesitation or stall when before I couldn't go this long at all thanks for all your help guys