Year and engine??
Year will tell you if there is one or two fuel pumps.
12volt power for the fuel pump(s0 itself runs like this:
Battery----Fuel pump Fuse(30amp)------Fuel pump relay(green base)-----inertia switch------fuel pump(s)
Fuel pump(s) ground is often near the inertia switch but can be at the frame rail by the tank.
Remove fuel pump relay there will be 4 connections in the socket, key off, test for 12volts at each contact, if not found fuel pump fuse is blown.
If found that is the fuel pump power from the battery, NOT relay power.
Turn key on, test for 12v again, second 12v contact is the Relay power that comes from the EEC relay(brown base).
One of the two remaining contacts runs to inertia switch and the other to the computer.
With key on the relay has 12volts but no ground so relay is OFF and not passing the 12v power to the fuel pump(s).
The computer controls the Ground for the relay.
When key is first turned to on, computer starts, and it grounds the fuel pump relay for 2 seconds, and then fuel pump will stay off until engine starts OR you turn the key off and then on again.
The inertia switch is in the passenger foot well or kick panel, it is a simple IN/OUT switch with a reset button on the top.
It has a weight inside and if the vehicle ever stops suddenly(accident), or rolls over, this weight will trip the switch and cut power to fuel pump(s).
If you hook up a test light/volt meter to a good ground and either contact on the inertia switch, then when key is turned on you should see voltage there for 2 seconds.
If so relay and fuse are good.
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