If you test the fuel pump wires for continuity across the fuel pump terminal, it must show continuity.
Fuel pressure dropping to 0 when ignition switch is turned off means there is a pressure leak and it could be the fuel pressure regulator or intank or even the fuel pump itself as the check valves are leacking. This explains the difficulty in starting.
At fuel pressure regulator return hose, clamp it to prevent fuel from returning and if pressure holds, the pressure regulator is bad. If pressure still does not hold, you would need to check the fuel pump. Quite often the hose between the fuel pump and housing ruptures resulting in pressure leaks and bing in-tank, you would not notice any fuel leaks.
Saturday, October 27th, 2012 AT 7:34 PM