One way to find a bad injector, one that is not delivering fuel or as much fuel, is with a laser thermometer. Point it at the exhast manifold where each cylinder's exhaust output would be. A cooler exhaust temp on one cylinder as compared to the others on that side would indicate a bad injector for that cylinder.

 

Well I haven't put in the new o-rings yet but thats because the truck shut off on me completely and wont start back up. I had to have it towed in. It'll turn over but no fire at all. Before it did that it kept blowing one fuse under the dash, not sure what it was for but it was the farthest bottom right fuse.

 

I'm reading a few ICP codes, maybe thats why the truck wont start? Should I start with replacing that sensor then work from there? I've also read that the HPOP may cause this as well?

 

This may be your fuel bowl heater fuse. I understand if it's blown, engine won't start. You can unplug the heater at the bowl, change the fuse, then try to start. Let us know what you find.

 

What year is the truck? What chip are you running? Other mods?

These trucks aren't all that complicated to get started in stock form, but critical items are:

1) Fuel pressure at the filter bowl, about 50 psi or more.

2) Sufficient amount of the proper oil, which, besides lubrication provides the hydraulic power to drive the injectors.

3) Sufficient voltage while cranking: at least 10.5 volts

4) At least 100 RPM while cranking

5) Good electrical connections among the PCM, IDM, injectors and a few of the sensors and actuators.

Assuming oil and CPS are OK, I have to agree that it sounds like an electrical problem that was causing your initial problem of suddenly cutting out.

Remove the chip/tuner and any associated wiring for the moment to eliminate that set of variables from the problem(s).

Like Les says, disconnect the fuel bowl heater and replace the fuse 'cause that same fuse powers the PCM. This is a pretty common failure.

Clean ALL your battery terminals real well and get the batts load tested. Replace both if either one is marginal. BTW: What kind of shape is your starter in after all this cranking? Still turn the motor over pretty strong?

And, as others have suggested, get your injector o-rings right and make sure your UVCH connectors are well seated while you're under there. Also a good time to see if your injectors are all spitting oil while you crank the engine. Check the harnesses AGAIN for chafe from the UVCH back to the components they connect to. Also check the injector wires under the valve covers. These have been known to chafe against pushrods.

I've been spoiled by my scanner, 'cause at this point, I'd start to monitor ICP and IPR duty cycle while cranking. Lacking access to a scanner, I'd unplug the ICP and see if that helps to start it.

If you do get it to crank, you might also want to do a blowby test to see if that starter fluid has aggravated things. Just set your oil filler cap upside down on the top of the filler tube and see if it stays there while the engine is running. But that test may be down the road a bit. Good luck!