1996 6.5L Turbo
 

Does anyone know why engine might shut it self off while running or ideling, but some times will run fine? Also usually will not start again once it is warm?

I'm not sure. there are quite a few 6.5 guys here that know their stuff and hopefully they will chime in in a bit. i moved this to the 6.2 6.5 forum to help ya gain a little more exposure.

Could be the PMD. (Spam Removed)

Whats a PMD ?

Pump Mounted Driver. Also known as FSD. Its the little box that can be a pain in the butt!

Could be a bad electric lift pump on the frame rail but most likely the stated PMD.

Yes, as stated before, it sounds like a PMD (or some call it the FSD) failure. It could also, however, be something electrical...make sure you check your grounds...engine and chassis...or it could be related to fuel...make sure there's no leaks in all of your fuel lines, and as stated earlier, it could be your Lift Pump, or Oil Pressure Switch. The lift pump should be on the frame rail under the driver's seat...you should be able to hear, or at least feel, the pump running. If not, run a hot wire to it, and see if it comes on. If it does, then it's not the LP that's bad, it's your OPS. They are both common failures on the 6.5. The PMD is a small black box on the Drivers' Side of the Injector Pump. It is about the size of a deck of cards. In '94, GM went all electronic with their injector pumps. The PMD, because of it's location gets and stays too hot, and the diodes inside of it burn out, way before they're supposed to. If you simply replace the PMD in it's stock location, it is sure to fail within a year or 2. To fix the issue, most of us 6.5ers mount the PMD on a heat sink and somewhere outside of the engine compartment. Heath Diesel makes a pretty good one, and warrenties his for 7 years. Kennedy Diesel also sells one. I've never heard of one of his failing in that time period. Others (I, for one) decided to go a cheaper route and build our own heat sink, and only replace the PMD and get an extended wiring harness, also available from Heath or Kennedy.

If you take the truck to the dealer, chances are, they will diagnose it as a faulty injector pump, and charge you out the A$$ for a pump and install...save yourself some money and replace the PMD in a remote location...

I sent you a PM about another site to check out...it's FULL of 6.5 experience and information...

May also be a problem with the fuel injection pump. If there is an electrical problem witht he cold start system as soon as the engine is warm it may shut down or run rough. If the vehicle is being driven upon warm up when you come to a stop the engine may shut down. Another thing to think about is the fuel pick up tube in the tank being clogged. If this is clogged it will also cause the problems you are having.

....99 times out of 100...it's the PMD or OPS/Lift Pump on the 6.5 though...

Jimmy I had a 94 6.5 .2500

Did you try to read the codes?

Do that first it will tell ya whats going on.then you can get more help .....and find out for sure:)
It should be under your dash by your left knee. just put a wire or clamp in the two little hole on
the top, I think its the side by side two on the right of the square thing with all the little holes in it. lol (i dont know what the name of it is,, sorry..)
your "check engine" should flash... 1 2a few times then the next is your code,, 33 or 34 or whatever.. try that.

you just might have to unplug your battery wire and re plug it in also,, sometimes these trucks just have to be reset..

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Im sorry to be so vague..

But it looks like this,,,,
{_}F/E/D/C/B/A{_}
{_}G/H/J/K/L/M{_} <_<<<<<imagine a little box around that,,:)

ALDL is what is called, put your wire in A/B