Yikes, looks like the DS4 IP was dismantled as well? Be sure to clean that as thoroughly as possible before re-assembling. And check in with us here before ordering a "new" one and getting ripped off by a place like Pensacola Diesel. Bad news is the DS4 was discontinued in 2020 and good running ones are only going to get more rare as there is no aftermarket support known as of this writing.
Use a piece of clear tubing to connect the IP return fitting at the front of the pump to the "T" hard metal return line. This is an essential diagnostic tool for determining if there is air in fuel or if fuel is making its way to/ through the IP at all.
If it was me, I'd take the supposedly good engine from the '94 and put it in the '93. Or convert the '94 to mechanical using parts from the '93. Save yourself the hassle of electronics on borrowed time. You're already ahead of the game if you have a transmission matched to the mechanical engine.
The same overheating problems that you had on the '93 will follow you to the '94. Do some searching/ reading around on here about the cooling upgrades for this engine. The basics are:
21" plastic duramax fan
Upgraded/ modified fan clutch to kick in at lower temp OR Electro-viscous fan clutch
Clean radiator and core support cooling stack (lots of space in there for debris to gather) or new radiator if your budget can swing it
High output balanced flow water pump from year 2000 or later. Many upgrade to the spin on fan clutch with the spin on water pump as opposed to 4 bolt
Upgrade oil cooler lines if you haven't already. Factory setup is disaster waiting to happen and when fail will seize engine in seconds
Some say upgrade to dual tstat, others contend single block off style is better. I'd personally recommend staying with the single stat so you have an easier time with clearance if converting to mechanical IP, and if you do a lot of towing/ are worried about heat just put in a lower temp stat.
Get the 97+ K47 air box and pull in cool outside air through the fender instead of sucking in hot underhood air
The above is a MINIMUM for keeping the engine alive. The following is getting more involved with funds but also IMO essential to long term life
Bigger & better turbo. Best thing you can do in addition to the bare minimum listed above. The stock turbo is undersized and a restriction that creates tons of backpressure that helps kill the engine
Upgrade exhaust to 3" downpipe and 4" after that
An EGT gauge is a must if doing any towing. Drill & tap the exhaust manifold under the turbo pedestal so you are reading temps PRE- turbo, not post- turbo
Boost gauge is also recommended for setting a mechanical wastegate and for any regular heavy towing
If you didn't already know, the factory cluster temp gauge is misleading as 210* is the max temp you want to run, if it hits 220* pull over and keep the engine running to let it cool down
I'm sure there's a few other things I'm forgetting, so look at some other introduction posts and see what others have recommended. Everything I know about the 6.5 I've learned from either my own stuff grenading on me and from this forum. Welcome to the loony bin
