This is my first post, so I hope that I can make sense.
After looking at all of the FAQ and other posts, I think that I have diagnosed my problem.
I have a 03 K2500 that I pull a 5th wheel with. I can't shut it off after pulling because it is so hard to start.
I would like to replace the injector pump as a DIY project. I have plenty of tools but would probably have to learn to retime the pump.
I know it is difficult to answer because everyone has different levels of ability. Before I spend the bucks, it would be nice to know if there is some hidden trap that lurks in there.
I am used to working with the 71 series GM in marine applications, so I have some experience with the monsters.

Thanks
GLEE

03 K2500?

Is it a 6.5 turbo diesel?

You may have made a typo, or may be better served in the Duramax forum, anyhow welcome

It was a typo
I make lots of those even when I proofread
It is a Turbo 6.5 in a 93 K2500

have you checked the lift pump?

I just put a new one on. The old one was shot.
I thought that was the problem.
It helped a little but that is not the solution. Even thought about repacing the oil pressure switch just to be on the safe side. I can hear snd feel the pump run.

Luke warm/room temperature water over the IP after hot-no-start will verify bad head/rotor failure on the DB2 pump.

Welcome to the 'Place, GLEE ..............

Hard hot-start is a definite symptom of worn DB2-4911 Inj Pump - check with any of several vendors here for rebuilt replacement - Huckstorff, Heath, etc

Absolutely, DB2 pumps are more wear prone than DS4, especially when exposed to Ultra Low Sulfur D-2 (notice my user name there).:rolleyes:

DB2's are no more wear-prone than the DS4, as they are essentially the same rotary distributor type IP - some DB2-4911's were built with excess head\rotor clearances, which have been causing hard hot-start since ca'93, long before anyone even thought about ULSD - Stanadyne upgrades consisted of new head\rotor replacement with closer adherance to spec'ed tolerances - still seems to be a lot of those bad DB2's on the road, even after all these years - and, I suspect some IP shops did not replace the head\rotors if they passed basic flow-bench testing, which does not take into account elevated temperature failures - worn starter motors, bad or unequal output batteries, poor cable connections could give same symptoms with a good IP.

Agreed, but ULSD aggravates the situation where DS4's, esp. 5521's, were modified to tolerate it. I don't want to start an argument here, but those pumps are not as similar as you think they are, especially where metering control is concerned. Don't get me wrong, your opinions are truly respected.

Any rotary distributor pump - Stanadyne DB and DS series, Bosch VP series, etc - where the fuel is the sole lubricant is susceptible to excessive wear from low lubricity fuels - this includes kerosene, JP fuels, ULSD, etc.

The DB2-4911 had built-in problem from the factory, with excessive head\rotor clearance - these have been prone to hard hot-start failures since 1992 with normal viscosity fuels, D1 and D2 - the lower viscosity ULSD will exacerbate the problem with excess clearance, but generates no more wear in the upgraded DB2 than in the DS4 - camring\rollers, pumping plungers, head\rotor clearances sealing, etc.

However, we have always advocated using ashless 2-stroke motor oil as lubricity-enhancer since those first DS4's began cratering due to steel camring roller disintegration - both series IP's were upgraded to include ceramic rollers at that time, along with the head\rotor upgrade in the -4911 - this also improves fuel viscosity, but will not cure the original head-rotor problem .

If a quart of 2-stroke added to 1/4tank fuel improves hot-start, you definitely need a replacement DB2-4911 - even good rotary pumps wear past serviceability over a period of years.

And, as stated, ULSD ain't helping, none, in either case, as the recent rash of DS4 failures have shown.

Fully agree, just that my point of reference was an existing DB2 that hadn't been upgraded vs late ceramic roller DS4. Nuff sed.

Early 4911 have a design flaw. Stanadyne even extended the warranty to 50,000 miles. Most made it out of warranty by a little. Other DB2 heads made in that era had problems as well. Stanadyne won't reveal the problem. Heads look like new when taken apart. I actually tested one on the truck. The engine was hot and I poured water on it a little at a time to see at what temp it would crank. Once it got below 105F it would start. Wear was not a factor. Believe it has to do with pieces that are pressed together in the head.
Tips you won't find on the net, except here.

Very interesting. My line of thought was: this being a 14 yr. old vehicle, a factory defect would have shown up a long time ago. Something that has made it this far, I think more of wear. I should have asked how long it has had this symptom.