I have a 2002 ford taurus that loses rail pressure. After about three hours I have no pressure at all. The car will also stall when I put it into gear unless it runs for about 5 minutes. There is no fuel odor. I can crimp the line ahead of the fuel tank and it still looses pressure. It dont find a return line to check. I have replaced the rail pressure sensor and it did nothing. Could this be a stuck injector or is it most likely a pump?
Loss of rail pressure
It can be: leaking injector, injector circuit, fuel pressure regulator, check valve in fuel pump. Try a noid light, it might reveal an issue with one or more injectors. Fuel injection test kits are not cheap, but they can reveal problems that may exist in the circuit that can cause an injector to hang open. Typically tho a fuel rail that loses pressure quickly is caused by a fuel pump and not an injector.