Functional glow plugs "required" to start truck?

[scraph]

I am trying to diagnose an issue where my truck will crank but not start. It is not CPS. When I turn the key to RUN I know it will _not_ start if the CEL and glow plug lights stay on and the Water in Fuel light doesn't come on. If the Water in Fuel light comes on (and clears) and the glow plug light extinguishes normally then the engine _will_ start.

It is not a cold starting problem... the weather is 75-85 degrees and _no_ fuel is being delivered when it won't start. I replaced the glow plug relay today and the issue seems to have gone away... will any of the possible failures of the GPR cause the computer to cut fuel? Does the computer require a functional GPR to deliver fuel?

[elibenson]

Is the fuel pump running while all this is going on? What is the fuel pressure read?
You shouldn't strictly need a GPR or an IAH relay attached to fire up your truck. I disconnect my glow plug relay if I plan on using ether to make a truck fire. I don't do that very often. I prefer gasoline fumes to start a cranky diesel.

It sounds to me like you have either a fuel pressure problem (either low or not at all), or a computer problem (computer is screwing up and not signaling the IDM to inject fuel).

[Jerryjust]

Try Gasoline to start,pour some on a rag and hold it at turbo in till it fires.Then check your codes while running. Works for me.

jerryjust

[scraph]

I'm beginning to believe its a computer problem or a wiring to computer problem... when it won't start and the CEL is on, a code reader cannot connect to the computer. :-/ Any insight on diagnosing between computer and wiring before I go throw a PCM at it?

[elibenson]

If your code reader is not connecting to the computer, the OBD2 port may not be getting any power. Check the fuse that runs the cigarette lighter. It also powers the OBD2 port. That fuse is easy to burn out with cell phone chargers, inverters, etc.