HP fuel pump on Universal M35

[pzmaria]

I'm still struggling with the engine and just don't know where to look for problems.
Previous problem with electrical pump was solved and running now.
Now my suspicion is HP fuel pump and need some opinion from members/owners.
Right now engine starts really hard and puffs quite a bit of white/dark mix of smoke for a minute until engine starts to warm up, after that there is no smoke. RPM is not steady as it goes up and down a bit. Engine runs to the point of reaching operating temperature and then slowly lowers RPM until it stops.
I need to mention that disassembling the engine for small rebuild noticed that water pump was seized to the point that the connecting notch on water pump was twisted. This Sherwood water pump is run by the cam shaft driving HP fuel pump. Just wondering if that might do something to fuel pump as for me it doesn't push enough fuel. With disconnected lines to injectors fuel pump just trickle fuel instead of squirting it high.
Any observations and pointers are greatly appreciated.

[two-rocks]

Catalina 36 MK3 does not exist....

Not sure what a "small rebuild" is and what parts were changed or why? Hours on the engine?

Sherwood water pumps suck, change it to Oberdorfer. Must have been a seriously neglected pump to seize enough to bend the drive parts.

Smoke: black is usually too much fuel (but burnt fuel), white can be unburnt fuel. Do your glow plugs work and are you using them? White smoke can also be confused with
steam, and that's bad.

How neglected are the fuel filters? fuel lines? Fuel tank?

[FPNC]

Connect the engine directly to a clean jug of fuel. Prime it, start it, and see if the problem goes away.

Make sure the valves are adjusted correctly.

Check compression.

Pull the injection pump to inspect the slide and the rotating cams that control plunger depth.

If compression is good and the cams are rotating as they should, send the injectors and pump to a shop for inspection.