Kubota RTV 500 Black smoke hard to start

[Flcracker13]

Good afternoon. I have a kubota rtv 500 efi that struggles to start and will puff black smoke out of the exhaust. Usually I can unplug the injector while cranking it and it will start then have to hurry and put the connector back on. At which point it will run half or full throttle but still puff black smoke. The plugs keep fouling. I suspected they may have mixed diesel into it being their older one was diesel. Drained the tank twice and filled with fresh gas. Still doing the same thing. I unplugged the map sensor and surprised it would sorta idle and run normal but still rich. Ordered a new map and the symptoms did not go away. I've disconnected the evap canister and have also searched a few different forms. Seems everyone has tried maps, ecms, iat, injector along with a list of other things but never got it fixed or didn't post it was fixed. Anyone have any experience with this? I'm going to check to see what the fuel pressure is either tomorrow or next week. Thanks

 

[Nicksacco]

Maybe a few guesses based on assumption diesel was run through it.

1. Check/replace fuel filter(s) - diesel will mess them up.
2. Quite possibly diesel mix still in fuel system - can you use air and blow everything out? Can you disconnect everything from tank into engine fuel system and flush and drain with something like carb cleaner?
3. Injectors could be clogged from diesel
4. Fuel pump messed up?

Maybe others have some more ideas

 

[GreensvilleJay]

Check engine oil...ANY 'gassy' smell ? Proper level or over full ?
'black smoke on gas engine' usually says 'rich' mixture

? how long have you run it ? It may have 'diesel' in the muffler, may take 15-20 mins to get muffler HOT and burn off any 'oil/'fuel' left in it.