What will cause my car not to start. I'm getting a 1720 code

Hello, if you have a loss of fuel pressure at the engine, it is likely you could have a fuel pump issue or something in the wiring to the pump. Keep in mind that the sending unit that makes the gauge work is associated with the fuel pump in the tank. Also keep in mind that this vehicle has 2 pumps - one in each side of the tank. They work to keep fuel balanced in the fuel tank, as well as provide fuel to the engine. One or both could have wiring or internal issues. The P1720 code indicates a problem in the networking of the vehicle, but could be due to low battery voltage from cranking it so much. Good testing is needed on this car to diagnose the concern.