CUCV II 6.5 "no start" nightmare solved

[NDT]

Wanted to document this as it applies to 6.2, 6.5 engines in both CUCVs and HMMWVs. After sitting for a few months, my 6.5 TD with DB4 electronic injection would crank but not start. As we know, these IDI engines need fuel, compression, and glow to start. I knew mechanically the engine is fine, the voltmeter was dipping during glow, so I assumed fuel. Started with the fuel filter, it was a bit nasty so I replaced it. Still no fire. Checked fuel pressure, good at 5 psi. Checked the fuel solenoid, clicking just fine. All the "online" 6.5 gurus tell you "did you replace the PMD" (pump mounted driver, only applies to H1 and CUCVII). So I did that. Still no fire. At this point I was starting to think the DB4 injection pump had died. Huge project to replace that, so I figured I better check more simple things first. Glow plugs, first one I checked was bad. Figured, one bad, others might be as well. Ordered a set of 60s. Upon installation, all the others were fine! What is going on here??? Jumped the glow plug relay with pliers, expecting a huge 80 amp spark. Nope just a weak spark. Uh-oh. Further digging revealed the nut on the glow plug solenoid was loose!! Very high resistance there was causing low ineffective glow. Fixed that and all is good. Picture shows the ring terminal leading to the glow plugs and the stud on the solenoid.
Lesson learned: Gotta have good hot glow to start a cold 6.2 6.5!!

Parts installed but not the cause: Fuel filter, Fuel pressure gauge, PMD, PMD extension cable, glow plugs. Ugh.

 

[Curtisje]

It costs like hell to go to school. Thanks for sharing.

 

[antennaclimber]

Clean, tight and reliable connections are essential for any high current applications. Even minor flaws will cause issues.

Glad to hear that your were able to solve the issue.