help please

[bumgas]

i have a ford explora 4l v6 runs on lpg the bigas system but it will not run on gas just hunts and spits and then stops but if you rev it it runs badly was told it was the rail that injects the gas but as far as i can tell it is all o.k ie gas comes out of each one and comes on and off any help would be great thanks( runs fine on petrol)

[lpgelite]

Has it ever run properly on Gas ?

If so, you need to think back to any event that has taken place since it last ran properly.

Has the battery been disconnected or run dead flat?

If so it may have lost its calibration.