Why is fuel pump relay getting no power?

the operation of most fuel pumps is controlled by the fuel pressure regulator
when the fuel pump gets to set pressure , the pump is switched of by the ECM at the relay level
maybe nothing wrong with your system just the system working as designed
if you have pressure in the fuel manifold when you turn the ignition on then the pump will not run but will if there is a fuel leak somewhere and the pressure drops off

There is an emergency fuel pump safety shutoff in case of an accident that will automatically shut fuel pump off so fuel does not keep pumping out at the scene of a crash. The reset button is usually in the trunk depending on what vehicle you have. Your manual will identify location for you.

The oil pressure sensor only keeps the pump running after the vehicle is started. If you turn key to on, the computer should signal to the fuel pump relay, turning the pump on for a couple of seconds to pressurize the fuel system. Then the computer signal stops. When the key is turned to start-cranking the engine- the computer again energizes the fuel pump relay, keeping the pump running until the engine starts.
If you have a voltmeter or test light, pull the relay out and check the relay terminals. One should be hot at all times-the power feed for the pump. The computer signal will be on the coil side of the relay-will have power for 2 or 3 seconds after key is turned to on. Or it will have a constant signal when the engine is cranking. If you can find both hot terminals at the relay, then start looking for a bad wire from relay to pump, or a bad ground for the pump, or a bad ground for the relay's coil side. Post back if unclear or other questions. When you pull the relay out, the diagram for it will be on the side of the relay-telling you which is the power feed and the terminal to the pump, and the coil side of relay, both the coil power side and the coil ground terminal.

Is the fuel pump relay getting power from the EEC relay when you turn the key on ? And then is the fuel pump relay sending power to the pump ?

It sounds like the pump is failing. That or sometimes not getting electricity. To check which it is, you could use a voltmeter or test light at the gas tank's electrical plug in. You need to check for power on the fuel pump wire when the engine is being cranked for starting. Do this when turning the key to on does not cause the pump to turn on for 2 seconds as it should. The fuel pump has power for those 2 seconds when key is turned to on, and again has power when the engine is cranked. You might miss the two second signal, so check for power when car won't start-when pump won't turn on-and with the engine cranking. If you have a signal then and still no pump coming on, then you must have a failing pump.
But if you have NO power to fuel pump wire with engine cranking, then it is a problem elsewhere-probably the pump relay (try a new relay if you haven't already). That relay is signaled by the engine computer when key is turned to on or when engine cranks . so you could do some testing at the relay if needed.

Did you reset the inertia switch that shuts pump down in case of collision?

Voltage drop test the electrical circuit , do know how to do automotive electrical testing . Lose connection , resistance in the circuit , lose ground Mastering Voltage Drop Testing with Pete Meier and Jerry Truglia Testing Electric Fuel Pump Problems with Voltage Drop Test

I'd have to test when problem is ongoing. When you first turn on key, no crank, you should hear the pump run for a few seconds then stop. For initial prime, the computer doesn't need rpm signal. Engine cranking, the computer needs to see rpm signal or it won't ground the fuel pump relay. W/o rpm signal, no spark at the plugs and no fuel injector pulse. I know your talking about fuel, but, when problem is ongoing, check spark and fuel injector pulse, engine cranking.
Intermittent problems are a pain, have to test when problem is ongoing.

Not guessing as to what the problem is , testing for voltage drop problems with a volt meter . posted a video on youtube yesterday . If your still looking for guesses forget it , no one on here could say for sure without testing the circuit an hooking up a scan tool to see if PCM is energizing the relay . Do yourself a favor an take it to a qualified repair shop . Fuel Pump Electrical Circuits Description and Operation If you can't learn how to test from this guy , better take to a repair shop .

No noise from fuel pump when you turn over the car .First thing get voltage at fuel pump relay checked, is there 12 volt to the relay.If no, then problem is again the relay.--------- To reconfirm the problem, try other test, that is remove the relay and by pass the relay terminals with a jumper wire .Then with 12 volt external battery give power to fuel pump connector and see, if the fuel pump starts, then its clear that fuel pump relay is faulty.----------- Also other problem can be fuel pump inertia switch.If the inertia switch is faulty then also fuel pump will not start.-------- The fuel pump relay on a 1995 Ford Explorer is in the power distribution
box, in the engine compartment, driver's side near the firewall.----------
The fuel pump inertia switch is in the right front passenger area
it is below the dash but above the carpet in the right hand corner.--------
Its a push button type inertia switch.
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Fuel Pump Activation
When ignition switch is turned to START position, PCM operates fuel pump relay to provide fuel for starting engine. PCM senses engine speed and shuts off fuel pump by opening ground circuit to fuel pump relay when engine stops or engine speed drops to less than 120 RPM. When ignition switch is in ON position, EEC power relay is energized (contacts closed). Power is provided to fuel pump relay and timer in PCM. Fuel pump receives power through fuel pump relay contacts.
Inertia Fuel Shutoff (IFS) Switch
All models use an electrical interrupt switch in fuel system. During a collision or vehicle rollover, electrical contacts within inertia switch open, shutting off fuel supply to electric fuel pump. Fuel supply is interrupted even when engine is running.
A reset button is located on switch assembly. If electrical circuit trips, vehicle will not restart until switch is reset. Fuel system should be inspected before resetting switch.
IFS switch is located under instrument panel, near right side of transmission hump. ----------- If the fuel pump relay, the inertia switch and fuel pump all checked ok, and fuel pump is working with direct 12 volt source to fuel pump.Then problem relates to computer.The computer (power control module, PCM) is faulty and has to be replaced.--------- This will help.Thanks.Helpmech.