Have you tried just priming the heck out of it before you attempt the first cold start? Just on plain diesel fuel, prime it like crazy, then try starting. The only other thing I can think of is air leaks in the system. Then when that doesn't work, replace the IP..

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'79 300D, Ivory "Gunther" ......going
'81 300SD, Metallic Blue Silver, The Grey Ghost.....going
'87 300D Turbo ...gone
'05 CDI.... gone