Military 6.5T Pickup

[Seabee15]

Ok, Here in Japan, We have a 97' GMC 6.5 Turbo 4x4, 4dr long bed 2500 pick up. It has a huge problem that has been leaving my guys stranded in the middle of no where.

The problem is that it will be running for 20min, then start to cut out. It will eventually die, and will sometimes start back up when put in neutral. It would start up for about 20-30seconds, then die out. It will run long if left out of gear, just parked.

We have replaced the fuel solenoid a few months ago, and thats the only issue we had with the truck after we releaved the off going command.

any suggestions for my motorpool guys?

I'm a gas engine lover, all it needs it fuel, air and spark and we will be on our way.

[Avec]

Sounds like a classic PMD / FSD failure. Even though you replaced it a couple months ago, I suggest starting there. Another common culprit is corroded grounds. There are a couple of them in the engine compartment going from the intake manifold on each side down to the frame. Clean and tighten those.

Start there.

[Seabee15]

PMD/FSD? what is that??? (please dont mind my diesel ignorance!)

but i will remind them to check the grounds...

[Avec]

Originally Posted by Seabee15

PMD/FSD? what is that??? (please dont mind my diesel ignorance!)

but i will remind them to check the grounds...

The PMD/FSD is the pump mounted driver or fuel solenoid driver. It is a black, deck of cards size box in the valley under the intake manifold. They go bad and cause unexplained shutoff like you are experiencing. To replace, you need to take the intake off. When it starts to go bad, it typically occurs when engine is warm or hot. It will start fine cold, and sometimes restart right away, but will shutoff at any throttle position and with no warning at all.

Check here
http://thedieselpageforums.com/tdpfo...ead.php?t=2938
Lots of info on the 6.5 and there are many contributors that are way, way beyond expert with the 6.2/6.5

For reference, I was driving my 6.5 to the hardware store and it quit like I had turned off the key. Restarted with no problems. About two weeks later, same thing, but this time no restart until next morning. Replaced the PMD and no problems. This was actually the second time I had to replace mine in the last 6 years, so I was probably past due.

[Redneck Rebel]

Wow even the US Navy turns to FSC for help.

[fortplainman]

rochester ny? i just noticed that in your info. im not sure if ive seen your truck around.

[crossy's son]

Yea, sounds like a PMD failure.

Replace it and buy the extended PMD wiring harness and move the PMD behind the bumper so it stays cool. www.heathdiesel.com

The PMD HATES heat and Detroit/GM put it down in the engine valley...wow

Replace and Relocate!!

[GM Guy 1]

what he said, and he referenced you to the proper place too. Heath diesels kit is the only one I'll put in my truck. plus, if you buy the heath kit, no need to pull the intake, just get skillful with some screwdrivers and pop the plug off.

[99-2door]

Originally Posted by GM Guy 1

what he said, and he referenced you to the proper place too. Heath diesels kit is the only one I'll put in my truck. plus, if you buy the heath kit, no need to pull the intake, just get skillful with some screwdrivers and pop the plug off.

This is true....replaced the one in my dad's 97 without removing anything. Reach down in and grabbed the plug and moved the ground wire.

[Seabee15]

Thanks everyone for your input!! This is Very helpful! And yes, even the US NAVY can use a little help here and there...and we all appreciate it!

Now just hopefully I can get funding approved for Heath diesel! I'll tell you how it goes..

[mr_goodwrench_0]

I thought all milspec 6.5's were DB2... If so, there is no PMD.

Bill

[red suburban]

depends on which vehicle the motor is in, if its a regular pickup (aka blue fleet) then its whatever was offered from the factory. if the motor is going in a military vehicle such as a humvee then its a DB2 pump.

[mr_goodwrench_0]

Ahhh, Ok. I'd vote PMD as well then.

Bill

[Seabee15]

Ok, just got back from the MotorPool shop, the guys say it just recently had a PMD installed, as well as a relocator bracket installed. They checked the grounds, and they checked out good. They say it may be a wiring harness.

And the truck will start, turn over a few times, and then just quit out.

Any other suggestions??

[mr_goodwrench_0]

Try getting them to unplug the optical sensor. You could be getting air bubbles in the fuel and the optical sensor is killing the engine because of it.

Bill

[oldred95]

I was told that when it comes to the 6.5 no matter what it needs a pump, that is on the 94+ models. IIRC 93 was still mechanical injection.

[Avec]

If it starts quickly, then dies, it is not the injection pump, but may be the lift pump, fuel filter or, as someone suggested, the optical sensor.

You can try to open an injector line and crank to see if you are getting fuel. It sounds like you are, then are not.

[mr_goodwrench_0]

All the 6.5s will run with a bad lift pump. It's just hard on the IP.

Bill

[crossy's son]

Originally Posted by mr_goodwrench_0

All the 6.5s will run with a bad lift pump. It's just hard on the IP.

Bill

Holy $hit you have an OBS 5spd suburban ??? i did not know that existed... that'd be awesome if it was a 454 haha.

[mr_goodwrench_0]

LOL I prefer the 6.5 to a 454, but thanks for the props. :) It's an NV4500. It seems that NOONE has seen an OBS standard 'Burb. This one has full leather interior, power everything and real oak trim pieces around the rear HVAC etc.

Bill