I have a 1997 Chevrolet Suburban with a 6.5 liter turbo diesel engine with 235k miles on it. Lately I've been having problems with it just dying-out on me, especially when I pick the kids up at school or on the way home from church. Examples over the past two months:

1) Hard to start. But once it starts, which is most of the time, it will idle for up to 20 seconds then just die on me. Other times it will run fine for up to 20 miles, then start "surging" on me in traffic, then it will completely die at a traffic light. Sometimes then I have to restart it several times, only to have it die on me as I push on the pedal... then it will run fine again. (the transmission runs fine, so I believe its not the problem).

I've had a mechanic student over here trying to help but its costing me a lot to find this problem! The first thing replaced was the fuel filter, which came out black and utterly filthy! ...I felt so happy to think that such a simple thing could fix my truck....but the next day I learned my problem was not solved!...Next he replaced a relay switch under the hood (located on the driver's side of the engine). The first thing I noticed is that the turbo once again began to work, but the darned vehicle started acting up again the very next day....Then a couple weeks later he decides its the in-line fuel pump/regulator thingie, and its replaced (Its the pump under the truck, along the frame rail, directly below the driver's seat).....But I'm still having a problem!

A few miserable days passed and I replaced the fuel cap at the recommendation of a neighbor...problem not fixed.... Today I checked for any cracks in the fuel line but didn't see or feel any. I've even checked the fuel relay fuse inside the fuse box. Anyone have suggestions?

I hope its not the injector pump which costs over 1k. It's a bit too expensive to buy right now. Thanks ahead of time for any help!

You need to take it to A Chevy Dealer and pay to have it check out (a lot cheaper then replaceing good parts) There is a problem with the ign switch on k trucks causing them to shut down but I dont think that would cause a diesel to shut off.
You said the fuel filter was very dirty ?? Run some diesel fuel cleaner in it because there might be a lot of dirt in the injector pump.
All the diesel problems I worked on had injector pump problems. I would try using a good aftermarket fuel cleaner (2 tanks full) and see what happens.
Not to many people know how to work on a diesel and I would still think about having a Pro looking at it.
Does it blow out a lot of black smoke on start up after it shuts down?? How is the air cleaner (very important in a diesel)

There are two things i would check out. I have exactly the same set up as you although mine is a 4x4 with 160k. When I removed the fuel filterI found sludge in my filter bowl also. I took the filter bowl out and found that the stand tube in it (this is the water fuel seperator) had rusted away. because of this the fuel wasn't getting filtered properly. I replaced it with a new one for around 100 bucks. I also replaced the pmd and mounted it remotely with a heat sink. for around 300 or 400. If you look around the 6.5 diesel web sites you'll see that that electronic gizmo is the nemisses of the engine. Hope this helps.Rich

FSD/PMD is a common problem.

So are bad grounds/connections, and ignition switches.

Visit www.thedieselpage.com.

Tons of information there.