You need to be specific. Are you testing at the fuel pump relay? The automatic shutdown, (ASD) relay? If you are testing for voltage at the connector for the fuel pump, you had better not have twelve volts there unless the engine is rotating, (cranking or running). The exception is you should see twelve volts there for one second when you turn on the ignition switch. If you are able to hear the hum of the pump for that one second when you turn on the ignition switch, the pump circuit is working.
About ninety five percent of crank/no-starts that involve a dead fuel pump also include no spark. That is why I asked if you have spark. Too many people get hung up on the first thing they find missing, and overlook the rest of the symptoms. You could have a problem in just the fuel pump circuit, but those account for perhaps one or two percent of no-starts.
There is no kill switch. "Inertia" switches are a troublesome Ford thing. Some other manufacturers might use them, but I am not aware of them. Other than that initial one-second burst, the Engine Computer turns on the ASD relay when it sees signal pulses coming from the crankshaft position sensor and camshaft position sensor. The ASD relay sends current to the ignition coil(s), injectors, oxygen sensor heaters, and fuel pump, or a separate fuel pump relay. This way, if a fuel line is ruptured in a crash, there will be no fuel pressure in that line. With no pressure, the engine cannot run. There will be no signal pulses from the two sensors when the engine is stalled. The computer turns the ASD relay off when there is no sensor pulses. That stops the fuel pump from dumping raw fuel onto the ground where it would be a fire hazard.
Monday, April 10th, 2017 AT 4:20 PM