Hello! New here, as i'm at my whits end.

History... Got this truck for free 2 years ago from a farmer due to the break system/front suspension being shot.
Its a 1997, 6.5 TurboDiesel, GMC K2500 Extended cab.
He had the IP rebuilt, and he had the famous module re-allocation to the driverside fender, with the aluminum heatsink yadayada. But thats about all he had done to it.


I fixed the above issues, and drove it for 3 years without a problem. It was a daily work truck for landscaping, and a band-truck for gigging around B.C. Canada.

Never gave an issue.

Untill one day, after sitting for a while I whent to run it alittle, turned the key, the WTS light came on for a brief moment, and when out.

Of course, i figured it wouldnt start without a propper glo-plug burn, but tried anyways. Two outof Eight cylanders seemed to fire, and it whent to a dead-cranking sound.
I turned the key again, and heard the usual click of the gloplug relay, and the stutter noise i always hear ( fuel pump?) And this time the gloplugs stayed on longer. But the same thing happened! A little kick, or sputter, or whatever you want to call it, But no start, and back onto the starter, dead cranking.
I tried again, this time the gloplug light stayed on for 3 seconds, and it BARELY ignited in ONE cylinder, before falling back onto the starter with not even a partial "engine wants to start" sound like most cranky diesels make.
I of course tried this over and over for 15 mins untill the batteries were dead.


I put it on charge over night, feeling alittle defeated.
The next day, it fired RIGHT up, after the gloplugs ( WTS light) were on the usual 10 seconds or so.
As if nothing had been wrong.

Some weeks whent by, i licensed it, started driving it for work. started flawlessly for weeks.
Randomly one early morning, i noticed the WTS whent out a little quick... and i remembered. Sure enough, same little Kicks, but no start, and back to dead cranking.
This time, i tried triggering the gloplugs on and off with the key aslong as they would go, several times in a row before cranking... But the same 1 or 2 cylanders fired, no start, back to a dead crank.
I didnt even put it on charge, though i tried untill i heard some battery droop.
Next day, it fired up, even on low batteries, first try, no problem.


I have just had a long day, because it decided to do this to me after work.
Ater multiple good sameritans burned through their batteries jumping it, and a whole HOUR of this same symptom, even after using a crescent wrench to jump the glo-plug relay terminals and observing the engine-compartment light dim every time, showing voltage draw from the gloplugs....
i had to leave it and hitch a ride.
I know, im gonna walk up to it tomorrow, and the basterd is gonna start right up like nothing ever happened, bringing around that gaslit-feeling. As if im the crazy one!

Could this be the mysterious glo-plug controller?

Ignition key?

Anyone ever even had this happen?

thanks.. Thomas.

 

That engine is all computerized, so the first thing to do is check for codes. Since it works fine when it works, I'd say it does sound like an intermittent electronic problem. There's not really anything in the mechanical systems that could do that.

 

Have you tried a new pmd?

There's a 6.5 diagnostics checklist that might help you out.

https://www.google.com/search?q=6.5+...obile&ie=UTF-8

 

You can try a known to be good PMD.

Do not try a PMD that is not mounted to a heat. Sink. They fry in a hurry.

Only buy made in the USA PMD extension cables. The Chinese cables are crap and just as likely to cause an issue as fix it.

It could also be a ground - there's several.

The engine wiring harness, the injection pump harness,

I had a truck that had a pin suddenly lose connection.