My jeep wrangler TJ 4.0 ltre has recently been converted to run on lpg injection or petrol, automatic switching.A problem arose after about 250 kms when it would not switch from petrol to lpg, took it back to the installer who recified the problem in minutes, app 500 kms later the jeep would not start I thought because it was now switched to lpg, starts on petrol, had it taken to an lpg installer explained the problem he had the problem sorted in minutes, but would not show me the problem.My jeep now will not start, had the original installer back to look at the problem, he says it is the jeep's ecu, no signal to the injectors, removed the ecu, part number 286AC, fitted an alternative ,not the same part number, jeep started, saying this is not suitable as it will not operate the air con & other functions, need to have the original repaired. I have taken my original ecu to be repaired, they say the ecu is not likely to be the problem as they are not like for like, not a proper comparison, they will run a scan but perlimonary checks appear to be ok. Also To get the system to change from petrol to lpg I often had to rev the engine.My gut feeling is it is a lpg system problem.How can I discover the problem & rectify the situation.Help Ian

remove power supply to LPG system, should be a fuse close to battery, or possibly behind glovebox. Run original ecu on petrol. If everything ok now, go see lpg installer and show him it runs fine when lpg disconnected