Basic run down on the situation

Purchase forklift from the auctions , ran and drove fine got delivered to my sisters house and driven off the tilt tray , she drove it and parked it up , was low on fuel and topped up , tried starting again and nothing, I came down and tried starting it no luck , checked all basic stuff to make sure wasn't safety lockout and no luck.

Checked it has spark and cleaned the spark plugs

Removed injectors and had bit **** on them and cleaned them out

Fuel getting to injector rail when cranking

Drained the fuel tank and pulled pickup out and was clean as.

Can run it on starter fluid but won't continue to run

Connected it to lpg gas and still no luck

My concern it's something ecu related as not opening injectors to fire , when cranking over can see engine lights on and spanner come on , I'm trying to work out how to clear codes without a scan tool or even read them to diagnose , any help would be awesome cheers.