EFI Fuel Pump Wiring Question

[Alphamacaroon]

Hi all, just ran into an inconsistency in the Coyote install manual and thought I'd ask before I cut any wires.

Background: Installing a Gen II Coyote in a Gen III Coupe and want to use the ECU to control the fuel pump (instead of manual switch).
Problem: The manual shows cutting a jumper wire, but my fuse panel shows the jumper wire to a different location

Here's what the manual shows:

109369

Here's what I have:

109370

From what I can tell, my harness has the pump control leg of the relay connected to the EFI or COIL fuse instead of the pump fuse. My guess is that maybe they updated it to allow the ignition switch to control the pump rather than relying on a separate pump switch?

Anyway, on to the question: can you see any issue with cutting the jumper (indicated in red below) from the EFI COIL and connecting to the Coyote pigtail connector?

109372

I can't see any issue with it, but thought I'd ask to make sure.

[brewha]

That red wire looks to be the power for the pump relay which is what needs to be connected to the EFI system. Cut the wire end furthest away from the relay. The good news is that red wire looks to be a lot longer now and should be easier to connect to the EFI.
The EFI cpu will run the fuel pump for about 4 seconds to prime the system at iginition on. The fuel pump will not run again until the EFI cpu senses crank or distributor rotation.
Good luck.

[freds]

The Ford PCM feeds the signals to control the fuel pump and cooling fan to relays in the Ford fuse/relay box. The output from each of those relays have adequate electrical power to control a fuel pump and a cooling fan. Adding the ffr fuse and relays in series is an unusual electrical thing to do.
To be sure I asked ffr tech support if it would be OK to not use the ffr/Ron Francis fuse/relays. Read my question and their answer below.


"Question: Is there any downside (other than not having the FFR fuse in line) to using the Ford green wire directly and relying on the Ford JC4 fuse and relay R4. That will be an easier and more secure fix than me messing with that relay receptacle connection.

And while I'm at it: Ditto for the fan JC2 and relay R2 for the cooling fan.
Answer: There should be no issue using the Ford Fuel Pump circuit instead of the
Ron Francis circuit."

My coupe is not finished yet but I have run the engine often and for long periods while charging the A/C and everything works exactly as it should.

fred

[edwardb]

Agree on completely bypassing the Ron Francis (RF) relay for the cooling fan when wiring up the Coyote. In that scenario, none of the RF wires, circuits, etc. are used for the cooling fan. Route the Coyote cooling fan wire directly to the positive terminal of the fan, ground the other side, and done. The Coyote PCM/PDB does the rest.

For the fuel pump circuit, it's a little more complicated. First, the Coyote PCM/PDB setup doesn't include an inertia switch, and that's a pretty big deal. For a high pressure electric fuel pump installation, an inertia switch is an important safety device and should be used. The fuel pump relay in the RF fuse panel, along with the accompanying inertia switch wiring and device, provides what's needed. Second, the situation has gotten a bit confusing because Factory Five Coyote instructions have had differences plus the RF harness has had several revisions. None of which have always agreed. Here's my take on the situation, and how I've wired two Coyote fuel pumps:

- I don't see any advantage to having two power sources for the RF fuel pump relay. One for the pump itself and the other for the relay coil (e.g. EFI or COIL fuse). This is a recent change from RF over previous versions.

- Breaking into the fuel pump circuit as the current Factory Five instructions show only has the Coyote PCM/PDB fuel pump wire controlling the relay coil. I don't see any advantage to that either, e.g. leaving the RF fuel pump fuse in place and having that on the fuel pump circuit. Now you have two fuses in the circuit. One on the Coyote PDB and one in the RF panel. Unnecessary complication IMO.

- Early instructions cut the main fuel pump wire from the RF panel fuse location, and that wire provided power to the pump as well as the relay coil. The Coyote fuel pump wire was attached to this cut wire. This did a number of things. First, took the RF fuse out of the circuit. Not needed. Second, allowed the relay to still provide the inertia switch function. To confirm, the inertia switch is on the ground circuit of the relay. If the inertia switch opens, the relay ground is broken and the relay opens. Thus turning off the pump. Third, used the RF fuel pump wire going back to the tank and pump connector to power the fuel pump, but exclusively controlled and fused by the Coyote PDB relay and fuse. I've saved this instruction page from early Factory Five Coyote installation instructions, and what I use and still recommend.

https://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Misc%20Pics/Fuel_Pump_Tap_Coyote_zps6zbfapiw.jpg (https://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Misc%20Pics/Fuel_Pump_Tap_Coyote_zps6zbfapiw.jpg.html)

For this most recent RF revision, I would cut both the orange wire from the EFI and COIL fuse and the brown wire from the fuel pump fuse, and attach both to the Coyote fuel pump wire. Now you have RF power source out of the circuit, Coyote PCM/PDB providing power and controlling, and the inertia relay still in play. Hope that makes sense.

[freds]

[QUOTE=edwardb;371899]Agree on completely bypassing the Ron Francis (RF) relay for the cooling fan when wiring up the Coyote. In that scenario, none of the RF wires, circuits, etc. are used for the cooling fan. Route the Coyote cooling fan wire directly to the positive terminal of the fan, ground the other side, and done. The Coyote PCM/PDB does the rest.



For the fuel pump circuit, it's a little more complicated. First, the Coyote PCM/PDB setup doesn't include an inertia switch, and that's a pretty big deal. For a high pressure electric fuel pump installation, an inertia switch is an important safety device and should be used.

I agree completely, I didn't detail the fact that I did wire in the inertia switch. As usual Paul, you go into really meticulous detail!