Daihatsu hijet 1300 16 valve EFI dual fuel LPG problems

Hi i was driving on lpg and the engine warning light come on It shuddered  then stopped . I got it going on petrol  then when i put it back on  lpg it worked fine till i stopped .I would start it back up on petrol again and it would work fine .
Any way it seemed to sort it's self out and was running fine on lpg when I stopped it would not stall . Yesterday when I was driving and switched it on to Lpg it stalled again But got it going .. Today i was driving on Petrol  Put it on Lpg heard a pop and hiss and smelled gas  ? Now it will try on run on LPG but dies  and stops running ... Any ideas what wrong ?    .. Cheers