The lift pump only supplies fuel to the ip inlet. After that the lift pump has no bearing on pressure or injection pulses. If the lp is running, it's good enough for at least idle and purging air.

I'd advise you make sure the shut off is working rather than a click. It probably is working right if it's new and is making a click noise.

Other than that, you're down to a pmd failure, ip failure or it could be air in the ip.

If the lift pump has positive pressure at the inlet you should be able to purge enough air out for it to run with a couple crank cycles.

If not, pmd or ip failure.

Something like a crank sensor or optical sensor would set a dtc code, although weirder things have happened.

Ip and pmd can fail with no codes.

Have you cleaned the passenger rear manifold ground wire yet? That's the PCM ground and if this has corrosion under it will cause a no start/stalling condition. It has to do with increased resistance so it doesn't take a lot of corrosion/schmutz.

Gm 6.5 diesel trucks are weird that way.....


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