Holley Sniper Fuel Pump Wiring

[gkp200]

I asked the question here, but I didn't get an answer:

https://thefactoryfiveforum.com/show...inertia-switch

So I'm trying to run the wiring for the fuel pump. I'm using the RF harness with the fuel pump in the tank. I want to keep the relay, fuse and inertia switch. So do I cut the jumper in the fuse panel as shown in the wiring manual and then connect the blue wire from the sniper to that wire that I cut?

Thanks for the help, wiring is not my best area.

[Papa]

I read that you want to use the RF fuel pump relay, and that is certainly an option. Just understand that you will now have two relays in the fuel pump circuit. My approach leaves the RF circuit in tact and unused by simply tapping the Sniper fuel pump control wire to the fuel pump positive wire. You can put the inertia switch in line with either the positive or ground wires to the fuel pump. I believe you can wire as you describe, just be sure you connect the Sniper wire to the correct side of the RF relay. You are essentially using the Sniper control wire as the RF relay trigger.

Dave

[gkp200]

Dave,

Thanks. So you depinned the fuel pump + wire and replaced it with the blue sniper wire and then installed the inertia switch into that wiring as well. Doesn't that bypass the fuse? Is that a concern?

[Papa]

The Sniper is fused on the main power (red) wire that goes to the battery and protected via a fused circuit from the RF harness for the 12v switched power. I'm writing this via my phone or I'd include a picture of page 16 of the Sniper's installation manual. I did as you described for the fuel pump connection on my car; depinned the fuel pump wire in the harness connector (main to rear) and added a single pin weatherpack connector to tie the Sniper's control wire to the RF fuel pump + wire. I still need to address the inertia switch, but will either connect it in line with the + side of the circuit or possibly relocate the switch to the trunk and tie it into the fuel pump ground or positive wires at the pump.

Dave

[FF33rod]

Don't want to confuse the situation here but keep in mind the following
- Holley supplies a harness with a relay for the fuel pump. This relay supplies a switched 12V for the fuel pump on a thick blue wire
- the output from the Sniper that controls that relay is also a blue wire but smaller diameter. This signal wire direct from the Sniper controls the ground side of their fuel pump relay in their harness
- so you can use either a low current ground output direct from the Sniper to control the RF relay or use a heavy current capable 12V to either power the RF relay or go direct to the pump

So if you eliminate the relay in the Holley wire harness and want to use the Sniper signal to activate the fuel pump relay as part of the RF fuse panel, then it needs to go to the ground side of the relay coil (not that 12V side which is the brown wire that is referred to cutting in the manual)

If you keep the Holley relay in the wire harness then you can use that relay's output (heavy blue wire) to activate the RF relay by cutting and connecting it to the brown wire as described in the manual OR you can run the heavy blue wire all the way back to the fuel pump directly (it's long enough) OR you can cut the heavy blue wire short and connect it to the tan fuel pump wire in the RF harness (this bypasses the RF relay).

Inertia Switch: It's currently wired to the ground side of the RF fuel pump relay. If the switch is tripped, it's open and no ground is available. It seems it's intended for low currents so keep it on the control side of the relays not the high current that drives the pump. It can control either the ground or 12V side - in between either of those and the respective control connection on the relay. So in the case where the signal wire from the Sniper is used to control the RF relay, I replaced the ground connection that goes to the inertia switch with the Sniper control signal. That way you only have to cut/connect one side of the inertia switch differently. In the case where you use the Holley relay to drive the RF relay, you don't have to do a thing (the inertia switch is already controlling the ground to the RF relay). In the case where you drive the fuel pump direct with the Holley relay output, you have to figure out something else.

Hope that helps
Steve

[gkp200]

Steve,

Yes that helps. Have to think some more on how I want to wire the fuel pump.

[Papa]

If you decide to remove the Sniper relay and go with negative control, then you can tie the Sniper control wire to the ground side of the inertia switch and use the RF relay and wiring. This is how I wired my FAST EFI that I had before the Sniper. You have a lot of options.

Dave

[SteveP]

Once I learned that the RF harness runs the fuel pump all the time and the Sniper only runs it on demand, I decided to use the Sniper relay for control. It seems like most who decide to do this use the RF wire to the fuel pump. I think the Sniper blue wire is heavier gauge and therefore able to handle more current. I have a larger than stock Mustang fuel pump. Is there some reason not to use the blue sniper wire all the way to the pump without using the RF harness at all? Simply disconnect the RF wire at the pump and substitute the blue Sniper wire?

[RJD]

+ 1 for using the sniper's relay and running the blue sniper wire all the way back to the pump. Just open the RF harness conduits and run it through there. I left the the original RF fuel pump wire in the harness, but repurposed it to power a trunk light on a proximity switch so it illuminates when the trunk is opened.

[SteveP]

Sounds good. Thanks.

[D Stand]

Attached is a detail for what I did. I moved the inertia switch to the negative trigger for the sniper fuel pump relay. Then ran the heavy blue directly to my fuel pump. If nothing else, this paints a picture of what the other folks are talking about with the small blue wire versus the large blue wire in the sniper harness.

Thanks Dale




sniper wiring asbuilt by Dale.pdf

[Norm B]

If you decide to remove the Sniper relay and go with negative control, then you can tie the Sniper control wire to the ground side of the inertia switch and use the RF relay and wiring. This is how I wired my FAST EFI that I had before the Sniper. You have a lot of options.

Dave

I did the same thing with my Sniper install. The Sniper fuel relay control wire is the small blue one. I found running one small wire back to the ground side of the chassis harness fuel relay way easier than the other options available.

I don't have a RF wiring harness due to Transport Canada restrictions on kit cars in Canada. I used a 12 circuit hot rod harness and didn't have a hot in run and/or start circuit except for the coil feed wire. Holley specifically recommends against this circuit. I repurposed the Sniper fuel relay as a power supply relay by connecting the small blue wire on the relay directly to ground, the small pink wire was spliced into the coil feed circuit and the big blue wire was connected to the big pink (12 volt switched) on the Sniper main connector. This provides a clean power source directly from the battery.

[SteveP]

Am I correct, is there a significant benefit in using the Sniper to control the fuel pump? The more I think about it the fuel pump probably runs the whole time the engine is running with the Sniper so it isn't much different than the RF constant on. Maybe there are other benefits I haven't read or thought of. For example, do we need the larger gauge wire form the Sniper to handle the curreny draw of the larger fuel pump the Sniper requires?

[SteveP]

Dale, I appreciate the drawing.

[Bobby Doug]

Am I correct, is there a significant benefit in using the Sniper to control the fuel pump? The more I think about it the fuel pump probably runs the whole time the engine is running with the Sniper so it isn't much different than the RF constant on. Maybe there are other benefits I haven't read or thought of. For example, do we need the larger gauge wire form the Sniper to handle the curreny draw of the larger fuel pump the Sniper requires?

You are correct the Sniper unit has the pump running all the time. That is the reason for the return line. I completely removed the Holley blue pump wire. I am using the RF harness with the inertia switch. Sniper unit runs great without it. Why complicate wiring with adding additional wiring? All you are doing is creating additional potential failure points. I learned long ago (KISS) Keep it simple stupid.