I have a 2004 Hyundai H-1, 2.5 diesel, with a weird issue. Its currently at 170k KM.
The car will start by rolling it and letting the clutch out, or by starter and introducing a tiny amount of starting fluid to the intake. However, just cranking it alone will not start it, no matter what. Doesnt matter if the engine is hot or cold. The car runs just fine as long as it starts.

I replaced the map sensor and the crank sensor. Fuel filters are good, glow plugs and relay is good, starter is good, and plenty fuel reaches the injection pump. Compression is also good. No error codes in OBD scan.

When I crank the engine it doesnt seem like it has any intention of starting. Its like a gas engine with no spark plugs. I suspect the injection pump is at fault here? I dont have much experience with these electrically controlled pumps. I assume there is some sort of a "start" mode to build pressure before engine start, and that doesnt work? There are some various humming noises coming from the injection pump when the ignition is on, but they are not consistent.

Anyone else experienced an issue like this?
The pump is marked;

33105-42600
104700-9071

Please let me know if you think anything else is causing this. It would be great to know before replacing the pump, as they are quite expensive
Thanks in advance.