its an ef v8 stock, when i start it on petrol it shakes and turns off, start it again rev it it stays on, you drive it it revs out changes a lil harshly but doesnt go far at all, the gear box drops gears normally but the car moves real slow and occasionaly back fires, flick it onto gas and its fine, thought i might not have petrol in it, pumped $30 premium in it (thats all i always put in) still same thing.

becuse it runs fine on gas ive narrowed it down to either fuel pump injectors or dodgy fuel (only drove for about 2kms after putting more fuel in it)

could it be anything else? very strange as its driven on fuel for about 40kms atleast once a week too..

im gonna go with the fuel pump champ, get into that boot and check it out

Do the fuel filter first, then do a pressure test on the pump delivery. If you use LPG all the time, it could be your injectors.

^^^ as stated check the fuel pump, but before hand just change the fuel filter too, its under the rear passenger side door, just infront of the rear wheel. $15 max for a fuel filter and 10 mins to change, also should give an indication how clean the fuel system is (or isnt).

i'd say injectors! as others have said though, start with the cheapest items first.

when you turn the key to ignition, can you hear the fuel pump prime?

Aahhh if you only knew what it was...

That stupid round breather thing attached to the side of the air inlet, it was loose and just sitting there disconnected! unbeleviable how such a small thing could make such a big difference, i put it back in and titghtened the clamp good as new again.

Whats really strange though is that i though gas depended alot on air compression, so technically it should be worse on gas with this thing off then on petrol.

Anyway no questions asked problem solved, glad it cost me nothing to fix.

Thanks guys