I have an XG ute on LPG. It has always run well on gas but was rough on petrol. This has steadily gotten worse until now it misfires all the time. Today I put in a new fuel filter which made no difference so I pulled the fuel rail and checked the injectors. Turning over the motor, injectors 2, 4 and 6 were not working. I swapped over 1 and 2 with the same result. I know this is a batch type injection system so it appears that one "batch" is not working.
Am I right in assuming this and what could be the cause.
Basically, I need a list of things to check before I take it to the mechanic
Cheers