1988 to 1989 saw some changes
This is the 1988 lay out of relays:
https://ww2-secure.justanswer.com/uploads/apjp02/2010-06-22_112812_Graphic.gif
In 1989 they moved the EEC and FP relays under the fuse box, seen here:
http://i.fixya.net/uploads/images/db2c160.gif
So you could have either
The FP relay will have a GREEN base/plugin, the EEC relay will have a BROWN base
Thats how you tell which is which in any year
In 1988 Ford used a Fusible Link to power the fuel pump, it runs from starter relay(solenoid) Battery Post, to the FP relay base.
When FP Relay closes the Fusible link power is sent to the Inertia Switch in the passenger side of Cab, on the firewall behind glove box.
On the inertia switch will be a Pink wire, and that runs to the Fuel pump in the tank
In general the FP Relays wire colors are
Fusible link power----Yellow or Black/yellow stripe
Out to Inertia switch---Dark Green/yellow strip
Red wire--12v to activate FP relay comes from EEC relay closing
Light Blue??--to computer, it Grounds this wire to close FP Relay
You should use the FP relay, you just need to do some rewiring
The Red wire on FP relay can be hooked to Key On power, which you will find on the EEC relay base, the Red/green stripe wire should be key on power
Then Ground the FP Relays Light blue wire
So key on closes relay and fuel pump starts
If you want a safer and better system then use an Oil Pressure SWITCH on the engine
Run the light blue wire to that switch
When engine is off, key on the FP Relay will stay open, no Ground
When engine is started oil pressure closes the switch which Grounds the FR relay and it closes, turning on the fuel pump
Carb has a float bowl so has enough gas to start it, so fuel pump down't need to come on until engine starts
This is safer because if there is a roll over, or "accident" that breaks a fuel line, the engine will stall and fuel pump will shut off
It its simply a key on or dash switch fuel pump ON then fuel pump will stay on, and perhaps cause or feed a fire, not a good thing