Alright, I have some questions posted in the Jeep section since this is going into my CJ and then posted on the General board because I thought all of you looked over there too, but I am beginning to reconsider that.

Situation, using an 87 Mark VII 5.0L speed density motor for my CJ7 and the wiring has been hell. The fuel pump is an in tank pump and the relay and safety switch were in the trunk, so I just cut 'em out and am trying to wire them in.

So, here is my question: How do I wire up the fuel pump, fuel pump relay and safety switch? There are four wires that I don't know what to do with. One from the pump(two come out of the pump, one goes to the relay), two from the relay(four come out, one to the pump and one to the safety switch) and then one from the safety switch (two come out, but came from the relay).

Maybe you guys can help with this one too:
The start/run position power from the ignition switch (from the Jeep side) that gets wired to (Ford side) HEGO power, alternator enable wire and to the TFI module. On the 89 Wrangler it is a Yellow wire that previously went to the ignition module and spliced to a wire with a resistor in it to the alternator, and then spliced again to the ignition coil with a resistor. On my 85 CJ7 I have two seperate wires that do this wiring, so does it matter which one I choose? I have a light blue that goes to the starter solenoid and then also the ignition module, then I have a brown wire that is wired to the alternator through a resistor. Does it matter?

Thanks a lot guys.
Jason

<<snip>>So, here is my question: How do I wire up the fuel pump, fuel pump relay and safety switch? There are four wires that I don't know what to do with. One from the pump(two come out of the pump, one goes to the relay), two from the relay(four come out, one to the pump and one to the safety switch) and then one from the safety switch (two come out, but came from the relay). <<snip>>


Fuel pump:
Needs A+ (battery 12v)
Needs Ground

Relay:
Needs A+ to pull relay, or
Needs ground to pull the relay
Needs A+ from 12V source (battery)
Uses 12V source (battery) to provide A+ to component (fuel pump)
Needs a common ground (either to battery or chassis)

Safety (Inertia) switch
It is a switch. It is open (off) or closed (on). It is normally closed (on).

I don't know what the amp rating of the Ford safety/inertia switch is (I have two of them in my truck, an Early Bronco). It might be 25 amps, it might be a few milliamps. I suspect it can handle the load of a Ford EFI fuel pump. But I don't know that for sure, as I don't have it's specs.

So, you have to deliver A+ from the battery to the fuel pump. And you need to interface it with the EFI computer. Since Ford EFI computer controls the fuel pump, it typically (I do not have a wiring diagram for that year of car) does it through a relay. I would suspect that it does this by grounding the relay, as opposed to running 12v (A+) through the computer.

Point being, you can put the safety/inertia switch in any connection that goes to the relay with the possibility of it being opened (when it gets jarred/hit/whacked). That will open the circuit, and cause the relay to stop delivering A+ to the fuel pump. Which is all the inertia switch does. Note: Not having a diagram for that car, I am probably giving you bad advice.

The system, as you described it, goes like this:

--one from the pump(two come out of the pump, one goes to the relay): One went to ground, the one that went to the relay is A+ (eventually connected to the battery).


--two from the relay(four come out, one to the pump and one to the safety switch): The one that went to the pump is the A+ from the battery, the other was part of the connection to the safety/inertia switch; the one that the safety/inertia switch opens (off)/closes (on).


--then one from the safety switch (two come out, but came from the relay): this is the one that connects to the A+ (the battery) side of the relay.


I hope this did not help at all!!! How dare you put a Ford motor in a Jeep. We have early Broncos in need of transplants!

Thanks dngl, I am going to work on it a little today.
Later.
Jason

You should be honored that my Jeep will have Ford ponies, isn't a compliment?

I wouldn't go as far as to say honored... my general motto is that it is your money and none of my business!

Good luck! Let us know how it turns out.