Australian Car Repair Issues? Ask an Auto Mechanic for Answers ASAP
A very common problem with dual fuel Commodore.
How old is the petrol in the tank?
You could have a fuel pressure problem, ie: bad pump return valve or pressure regulator.
You could also have a larger than acceptable water content in the fuel.
If this only happens cold, try a squirt of carb cleaner in the throttle body prior to start up, to see if it makes any difference.
That is unfortunate if the system is turning off the injectors prior to switching to LPG.
No knowing which system you have, I would recommend you go to an LPG servicing centre who should be able to fix it for you.
If you would like to pay, although I am not really expecting anything, because I didn't fix your problem, you can send to Gary Rolfe,***** Everton Park, Brisbane QLD, 4053.
Thanks very much for your courtesy, you are welcome back any time.