Smoky Startup

[Snowbird 6.5]

I bought this diesel a year ago and all was well. I hitched up to my 35 foot RV and headed to AZ. Cracked the block in CO, and installed a used motor which I didn’t know much about. Used my old IP and coolant sensor because it was a newer motor with the PMD style pump.
Hard starting and Serious grey smoke until it’s warmed up. It seems to be fine after it’s warm. Changed the glow plugs and no change. Am I missing something? Was there anything else I

All the research I’ve done leads me to believe I have a bad IP relating to the cold start portion of the IP. The coolant sensor activates a solenoid internal on the pump which reduces the output pressure to reduce fuel delivery until warm. Am I correct so far?

I got the truck at a real good price but have invested weeks and much money into this beast. This is my first diesel but it seems pretty straightforward without a lot of extra electronics and such.

I’m just looking for some reassurance that I’m barking up the right tree and not wasting time and money before I send the IP and injectors out for rebuilding and write another big check. TIA for any thoughts you may have!

[DmaxMaverick]

Welcome aboard!

HPCA = Housing Pressure Cold Advance. It is internal and controlled by the ECT sensor, and should be a green wire connected to the IP (pink wire is ESS = Engine Stop Solenoid, the cylinder on top). It advances timing for cold starts (not reduce fuel delivery, which would actually prevent a start). If my problem were ONLY the HPCA, I'd tolerate smoky startups a lot more than the cost of a new pump. Test the HPCA by disconnecting it immediately following a cold start (then reconnect it after a bit). The engine sound difference should be very noticeable. Check the connector for 12V if it isn't (suspect wire, connector, or sensor). The same voltage source operates the high idle solenoid that is at the throttle linkage (holds high idle once the key is on and you tap the throttle). If it isn't working either, suspect a wire, connector, or the sensor. It may also be a fuse, but I don't recall which or if on 93 models.

Could also be the base injection timing is off (retarded), or your glow plug cycle is too short.

[Yukon6.2]

My truck had smoky starts when i had a leak in the fuel system.