ICE requires 3 things fuel/air mix, Compression, and Spark. ECM is doing its thing (+12 at both inputs and dual GND(s) AND pick up coil timing pulse) and fuel injector pulsing fuel.......wet plugs.
CORRECT fuel/air mixture. Some of the Hisun engines have a "spit" fuel injector which I believe to have been the 2 hole......find new 3 holers to get fuel/air mix to the magic 14:1 ratio.
DO a compression test....low compression can be due to:
!. Rings worn and scoured (fuel wash down of oil) cylinder wall. Some oil squirt in the spark plug hole will help seal rings and raise compression.
2. Old engine (sitter???) carbon flake gets under and/or between the valve and valve seat....usually the Exhaust....will have excessive valve clearance if not adjusted after carbon capture. Low compression but no real danger to valve. Multi-cyl engine, the running cyl(s) will drag along the dead cyl and then do a hot gas jet cut to the valve face. V cut notch.
3. Worn chain/weak tensioner....gives valve timing JUMPED. Pull lid and TDC the crank and check timing marks. Off a few teeth, poor run or not at all. Way off and the piston has a late night date with one of the valves.....bent valve cannot close....no compression...no run.
T/S as follows: Do the above checks.
1, Remove the air filter to TB plumbing......free unrestricted air flow and no possibility of gas fumes from air filter and air filter box.
2. Disconnect the fuel pump connector under pass seat.......no more injector dump fuel.
3. Dry plugs or better yet new spark plugs. Can always use old as spares.
4. Blow shop air into plug hole to dry the cylinder out........drop in the new plug.
5. Starter fluid is now the only source of fuel......carefully give a squirt while cranking over engine......IF lights off, give several semi-auto squirts for a longer run.
6. Engine is OK. Reconnect the air box plumbing. Remove air box lid and be sure air filter is clean and not slop oil soaked.
7. Feed the air filter a 1 sec squirt on the filter body. Restarts and with say a now 5 sec. run and die.
8. Reconnect the fuel pump connector. Back to stock. should start and run if fuel system is OK. If it goes back to it's old ways, injector is a spitter OR
9. Other inputs to ECM is making a rich mixture: IAT-----open and the ECM thinks the air temperature is at the South Pole.
MAP combo sensor.......engine load "signal" located in the intake plumbing at the throttle body. It also determined the
actual fuel delivery above the internal ECM map and dumps extra fuel....just lick the IAT functions as a "CHOKE".
May the T/S Genie be with you BEN