Yanmar YSB8 - Sputtering but won't start!

[Sailor_Grant]

Having issues with my Yanmar YSB8. Was running just fine, and suddenly died. Determined it was likely the fuel injection system.

Replaced fuel injection pump and injector, and when turned over, got the injector to pop and spray in the open air. After installing the injector, when cranking the engine over with decompression lever, then popping the lever to start, was able to get it to sputter a bit, felt like it was about to start, but could never get it to run steady state. Some white smoke was coming out of air intake when this was happening.

There is plenty of fuel getting to injector pump, and injector. Bled it dozens of times; that does not seem to be the issue (clean fuel coming out everywhere). Two thoughts: 1) could it be injector timing 2) could it be valve clearences?

Given it died suddently, I strongly doubt it is compression related, hence why I am not adjusted valves yet.

Any ideas on what this could be?