You will not have power to the inertia switch or pumps if the engine is not running. When the ignition switch is first turned on, you should have power for a couple of seconds to prime the fuel system. You should be able to hear the pumps running for this short period of time. The computer then shuts off the pumps waiting for ignition pulses from the distributor.
If you can locate the self test connector you can keep power to the pumps for diagnosis. The connector is on the pass side of the truck between the fender and the firewall. It looks like an unplugged electrical connector in the shape of a house when looking at the front of the connector. The top slopes on each side, and it has six slots for connections, two on top and four on the bottom.
To keep power to the pump, of the four slots on the bottom of the connector, run a ground wire from the slot on the lower right of the connector to a good ground. I use the battery ground.
This grounds the coil side of the fuel pump relay keeping the contacts closed, and power going to the pumps.
Fuel pump relay:
Red wire = power to the relay coil from the EEC relay.
Tan/lt grn wire = relay coil ground going to pin 22 of the computer and the self test connector. This is the point you ground to the battery negative.
Yellow = power from the fuse link on the fender starter relay. This is where the pumps get running power. It is one side of the contacts inside the fuel pump relay. If the fuse link is open, no power.
Orange/lt blu = power out of the fuel pump relay to the inertia switch.
EEC relay:
This relay supplies power to the computer, and sensors, and fuel pump relay.
Yellow = power from another fuse link on the fender starter relay. This is main power to the EEC relay contacts
Red = Power out of the EEC relay contacts to the fuel pump relay and sensors.
Red/lt grn = power from the ignition switch
Blk/lt grn = ground side of the EEC relay coil going to the computer.
The fuse links are like fuses. If they have opened up, no power. shady
I, recently, changed my starter's solenoid switch and was wondering about the three wires, that are attached to the starter's solenoid hot terminal lead, from the battery's positive post...
I thought they were, probably, some kind of fuse links... but, I wasn't sure what they were for, exactly...
I thought they might be for the fuel pumps... however, I wasn't sure...
does each pump have it's own fuse link ?? or, does one fuse link power both pumps ??
if one fuse link powers both fuel pumps... what do the other two fuse links power ??
I can hear my front fuel pump when it runs, located along the frame rail... but, when the front pump is runnning, I can't tell if my fuel pump, inside the fuel tank, is running, cause of the noise that the front fuel pump is making...
what's the best way to find out, or hear if my rear fuel pump is running... can I dissconect the power to front fuel pump, and send power, only, to the rear fuel pump, to find out...
you seem pretty knowledgable how a ranger's fuel injection system works, regarding the operation of their fuel pumps...
so, I thought I'd ask your advice... as, I'd like to find out, for sure, if my rear fuel pump is working, properly, as it's suppose to...