I own a 2002 Ford Ranger with the Edge package 2wd. Currently, the Truck will start and run fine but the Fuel Pump Relay will get to well over 200 degree F. Eventually the relay will fail. so
Hazard Fraught Multimeter
The Fuel pump ohms out a 2.1
The wire from the power distribution to the inertia switch ohms out at .6
The Inertia switch ohms out at .6
From the Inertia Switch to the fuel pump ohms out at .6
From the relay through the inertia switch it ohms out at .6/.7
Above could be a reason but the stuff below is probably the cause

If I pulled the relay and measure the voltage going to the fuel pump with the ign on and it measures at 6v. That goes away once I pulled the 50amp ignition/starter fuse
My LED 3rd brake light is slighty lit when the ign is on and goes off when i pull that same 50amp ignition/starter fuse. I don't know the voltage.
Thank you for you time. Im thinking a bad power distribution box

 

Welcome to the forum

Good testing

The 6v with key on is from computer's fuel pump monitor circuit, 5v to 8v, no amps
When you pull the 50amp fuse you shut off the computer

Fuel pump doesn't run with key on, well it comes on for 2 seconds to prime the system, then will not start again until engine starts, above 400rpm

In a 2002 Ranger fuel pump relay is probably a Micro Relay, base looks like this: https://www.gtsparkplugs.com/images/...lay-wiring.jpg

30 and 87 are for fuel pump 12v power, these two slots are connected when computer activates this relay
85 and 86 are used to activate this relay
87A may or may not be there, its not used in this circuit in any case

You can jumper 30 and 87, key on or off doesn't matter, fuel pump will come on, to test its amp draw

There are some videos on how to test amp draws, Google: test amp draw on a 12 volt circuit



Reads like your fuel pump is drawing too many amps, but at 2.1ohms it should only be drawing 6 amps, Relay is rated for at least 30amps, usually 40amps

Its a puzzler

 

Thank you for the reply. I wrote something longer...but I'm going to test somethings when I get home before....Thank you for confirming some things for me

 

Okay.
I measured 6 amps (+- .2) at pins 30 and 87 at the fuse box and 6 amps at the inertia switch. I really couldn't get a good amp reading on the 85 and 86 pins. it does pop up .1 for the 2 seconds. I'm also seeing 6v at the third brake light (when the ignition is on) the same voltage but with no amps as the ECU puts out.. When I jump pins 30 and 87 either with the multi meter or a jump wire, truck runs good and I see no heating in that area of the fuse box. when I put a relay in. it heats up quickly.
Went around trying to look for obvious signs of wear on wires and did not see anything.

 

85 and 86 have no amps, well may be 0.5amp

If motor is only drawing 6amps the relay should not over heat, so change it again to a different brand

The PCM relay is the same relay and draws 10amps
Wiper relay can draw 12amps when wipers are running
Blower motor Relay can be 15amps when HIGH is selected

 

Thank you for your time.
I have replaced the Relay with multiple brands, still overheats. OEM from Ford, a few from around the engine fuse box, a few from the junkyard. Same issue.
I am going to unplug the third brake light and see if that fixes the fuel pump relay overheating issue.
than
I am going to use jumper wires to connect a relay to the distribution box and see what happens.
Than Im going to use jumper wires to connect the relay on the coil side and a jumper wire/multimeter in the distrubition on terminals 87 and 30 to see if the relay is overheating on the coil side.

 

After some more testing. When I jump 87 and 30 to power the fuel pump, its the distrubtion box that gets hot underneath where the relay should go.

Is thee engine room fuse box something that can be opened up?

 

I have never done it before but engine fuse box has to be assembled and wires attach on the under side so the bottom should come off, look at the top where fuses and relays are, if you see screw heads then bottom is most likely screwed on
If no screws then its snapped on, will have tabs

Disconnect battery FIRST!!!!
You should see bolts that hold fuse box to inner fender
Unbolt it and see if you have enough slack in wiring to flip it over