I've got a TJ wagon with a parnell LPG system fitted. The car has stopped starting and running on petrol but runs fine on Gas. I've drained the petrol tank, replaced the fuel filter and tested the fuel Pump. the fuel pump seems to engage when you turn it over on petrol. The starter motor will turn over fine on both petrol and Gas modes but doesn't start on petrol.

I don't believe the problem is the immobiliser or otherwise it wouldn't start on Gas. The car did start on petrol once I replaced the filter for about ten minutes and then died again. This leads me to believe its not a problem with the injectors but somehow with the engine management system. Can someone give me some ideas of where to look now.

I am reasonably good with a multimeter so if there are any tests i can do to figure out the problem i would appreciate the suggestions.

do you drive it on petrol much??? you might have dried out and blocked up fuel lines and injectors...

we were driving it on petrol once a week on average but strangely it stopped working after driving it for a solid week on petrol to give it a good run.

how do i test if the lines and injectors are blocked

Whilst you're driving on LPG, can you switch it to petrol & drive it?

Is the system a vapor injection type setup that automatically changes from petrol to gas at 1500 rpm once the cooling system reaches a pre set temperature?