I own a 1998 GMC 3500 sierra (cube truck) with a 6.5 diesel. A couple of weeks ago it died all the sudden, then would not start until it cooled down (about 2 hrs) I got it to the closest dealership and they said it had a bad injector pump, I had them replace it, when I left, I drove it about 12 miles and it died again. I was low on fuel, but I knew it still had some left (1/8 tank on guage). I called and they towed it back. The next day they said it was empty, and from it running dry it had distroyed my fuel lift pump, they said it showed it was at 1 pound pressure. They wanted to replace it for 400.00, I called around and found it for 69.00 and easy to install. I started it up and took it home (ran fine with only 1 lb pressure). I replaced the fuel pump and left for work. went to breakfast and tried to start it, it would not start. I called a tow, but by the time they arrived, it turned over. I took it back and now they say it is the ECM. I have dropped over 2K on the injector pump and now the say the ECM. Could it have been the ECM all the time and that gave them bad readings on the Injector pump??
Thanks for the replies
B.

No expert here but try this. While the truck is idleing open the water drain valve. If the truck stalls and the lift pump is new, I'd suspect the oil pressure switch. The lift pump runs off the OP switch. You can show oil pressure on the guage and still not be running the lift pump.

You could also jump around the relay and see if it runs better and starts on time. Just a little test to check it out too.

Another testament as to why I don't ever want to take my truch to a dealer. And if I have to I want to be right there for every test and decision. I just have felt that they don't really know more about my truck than I do. And since my truck is long out of warrenty, they don't have to do the work.

Let me put it this way, Dealer policy is to replace the IP, ECM and fuel system at the drop of a hat on your dime if possible. They don't train their guys to know which part is failing and why, just take out the old parts and put the new ones in. In that respect, reading this forum gives you more insight to the workings of the IP than the avg. GM service guy had access to. His material was geared to show him what to replace and any suspected part on the pump (PMD) means replace the entire assembly. It's your job to fix your truck on the cheap.
Now that I think of it, A-1's whole niche is a reciprical of GM and their lacksadasical approach to fixing it.

What's your milage,Gm should cover replacement 'till 120,000 miles

Thanks for all the replys, I have 134K miles, the injector pump was replaced at 46K under warrenty, so this pump has approx. 90K on it.

90K is about the lifetime of a DS-4, not that they can't go longer.
How's it running now?
Having 1 psi on the LP maens there's a good chance you have a restriction in the fuel filter housing. Do you drain the water T often? How old's the fuel filter?
I find that back flushing the filter bowl and out the drain T with compressed air will dislodge crap you can't otherwise access.

There might be some lucky ones out there as far as finding a mechanic for the 6.5, but I be better off bringing my truck to the local kindergarden than to the local dealers for service. If you want to own a 6.5 or probably any light duty diesel(for that matter) you'd better learn how to work on it yourself, or open your wallet and prepare to CRY!

The lift pump runs off the OP switch.Not on a '98 mitch. ECM controls operation of lift pump, but you might try replacing the relay in the fuse panel under the hood that operates the pump, cheap and does give fits sometimes.

Replacing the fuel filter is a good place to start, they're a bit of a pain on the vans because they're under the drivers seat, next to the supply pump.
Oh, and that pump your got for $69, I wouldn't use that, I'll bet the box says either Master or Carter and they're both crap! OEM ones are good, but pricey, Delphi's are as good or better and a little cheaper.
Really need a scanner to figure out what the problem is for sure...

Actually the power for the lift pump stills has a path through the OPS once PCM does it's thing, so OPS is still a possibility, but problem suspiciously sounds like PMD. In the FAQs there is a thread link to stumbling & dying troubleshooting start there for more things before 100% condemning PMD, if & when you find the PMD to be at fault best bet IMO is the Bill Heath remote kit.

Moderator rant time again, directed at old timers here, suggest/cajole, etc that new members read Welcome Notes and FAQS in sticky's above; please do not continue to contribute to making the site get boring by answering a new arrivals questions without directing them to the info we collectively have already addressed time & time again

New arrivals I'm not trying to be a hard case with this, but after you have been here a while or have visited other sites you will understand why I'm a PITA about this point.

Rant over

Thanks for all the great replies, well I got the truck back yeaterday and it seems to be working great. I got the final low down on what they did. When I brought it in the last time, they found that the ECM was bad, they put in a new ECM and it failed again, they said it was due to a bad solinoid relay on the injector pump. this shorted out solinoid caused my original ECM to fail, and also the new one they put on. They replaced the solinoid valve and they checked the new ECM, they said it did not ruin the new ECM. Well they refunded the $200.00 tow when they said I ran out of fuel and distroyed the lift pump. They also did not charge me for the ECM ot the time it took them to repair the problems. So my final tally was to poay te 2K for the injector pump. So far the truck has turnrd on and off 4 times, thats 3 times more than normal lately!!