1996 Holden Commodore 96 Wagon That Dual Fuel Fitted Lpg Past Month Check

I have a 96 Commodore Wagon that has dual fuel fitted. When I use the LPG in the past month or so the Check Engine Light comes on (hence I don't use LPG). Yesterday the car wouldn't start at all on fuel. It will turn over but won't start on either fuel system. The Roadside Assistance person said that the problem is my fuel pump. Is is possible that is the case or would the problem be something else since it won't start on fuel or gas?