Coyote Control Pack Fuel Pump Relay

[Alan_C]

Is the fuel pump relay built into the power distribution box adequate for driving the fuel pump directly or would it be better to have a external fuel pump relay near the tank? When I bought my Aeromotive tank with built in fuel pump, the tech support at Aeromotive recommended use of their wiring kit with its own fuel pump relay. Overkill as I would rather not install the external relay if not needed.

[facultyofmusic]

That does seem overkill. The control pack instructions (https://performanceparts.ford.com/download/instructionsheets/FORDINSTSHTM-6017-M50B.PDF) show a direct connection to the fuel pump in all its diagrams. The fuse and relay for the fuel pump in the coyote PDB is rated for 40A; should be more than enough.

[progmgr1]

I had asked this question previously and got multiple answers, not all in agreement. My conclusion is that you can run the fuel pump from the Controls Pack, but then you need a heavy gauge wire running the length of the car. Depending on how you laid out the power wiring, it might be easier to use the Controls Pack to trigger a relay near the pump so you can keep the high current wires as short as possible. This is what I'm doing on my car.

Keith HR #894

[facultyofmusic]

Just curious Alan, are you using the Ron Francis harness?

[michael everson]

Everyone I built uses the Coyote green wire direct or the RF harness wire direct. No issues either way.
Mike

[Alan_C]

The short answer is no on the Ron Francis harness. My participation here is because of all the builds using the Coyote. I had a MK4 with the 4.6L DOHC predecessor to the Coyote. The car was sold for my current project, a 70 Boss 302 Mustang tribute. So my body harness is an AAW product for the Mustang. The engine side is via the FP controls pack and there is very few connections between them. Because of the length of the Mustang vs. a MK4, I have a longer run to the rear of the car. My battery is in the trunk along with the inertial switch. Placing a second relay in the trunk along with the inertia switch would be an easy thing to do. Since Aeromotive suggested the use of their relay, I have it.
I like the idea of a smaller gauge trigger wire to a trunk mounted relay. A little more complex, yes, but relatively easy to set up.
From reading the control pack installation instructions, the PDM mounted fuel pump relay looked to be adequate. The longer wire run in my case will add resistance or require a larger gauge wire. The space in my wiring channel on the PS is getting cramped, so a smaller wire will help.
Thanks for the commentary, as it gives me ideas to consider. There are so few Coyote based restomods on the Vintage Mustang Forum that I find I can better and quicker answers here.

[facultyofmusic]

The short answer is no on the Ron Francis harness. My participation here is because of all the builds using the Coyote. I had a MK4 with the 4.6L DOHC predecessor to the Coyote. The car was sold for my current project, a 70 Boss 302 Mustang tribute. So my body harness is an AAW product for the Mustang. The engine side is via the FP controls pack and there is very few connections between them. Because of the length of the Mustang vs. a MK4, I have a longer run to the rear of the car. My battery is in the trunk along with the inertial switch. Placing a second relay in the trunk along with the inertia switch would be an easy thing to do. Since Aeromotive suggested the use of their relay, I have it.
I like the idea of a smaller gauge trigger wire to a trunk mounted relay. A little more complex, yes, but relatively easy to set up.
From reading the control pack installation instructions, the PDM mounted fuel pump relay looked to be adequate. The longer wire run in my case will add resistance or require a larger gauge wire. The space in my wiring channel on the PS is getting cramped, so a smaller wire will help.
Thanks for the commentary, as it gives me ideas to consider. There are so few Coyote based restomods on the Vintage Mustang Forum that I find I can better and quicker answers here.

Ahh I see, makes sense. I'd still consider the wire gauge if you'll use a thinner wire. The fuel pump power from the coyote is supposed to be up to 40A after-all.

[Alan_C]

I appreciate the thought, but I will size the wire appropriately. A retired electrical engineer here, so be sure I will analyze and choose the gauge appropriately. I have a tendency to overthink or engineer what I do, always error on the side of caution. If you saw my analysis for the main power runs, this is nothing. I was mostly interested in knowing if others had used a second relay.
That said, I will go with the secondary remote relay in the trunk. One I have it and two I will integrate it with the inertial switch already mounted next to the battery.

[progmgr1]

That said, I will go with the secondary remote relay in the trunk. One I have it and two I will integrate it with the inertial switch already mounted next to the battery.

Exactly what I concluded, for the same reasons (retired mechanical engineer)

Keith HR #894