"Wiring an inertia switch and toggle switch on a Carb'd car"

[Busted07]

This is on a carb'd application, with a holley blue pump.

I know this is remedial, and i should know this, but i dont want to take the chance on screwing anything up. JRichker gave me a schematic on how to wire an inertia switch up to the fuel pump, but it all looks like spaghetti to me, because alot of whats included in the schematic, i dont need. I want to wire the inertia switch up, and put a toggle switch (theft prevention kill switch) hidden in the car as well. i know its not much to help prevent someone from stealing it, but every little bit helps.

I have the stock inertia switch still hooked up in the car, but im not sure how to splice the fuel pump wires into it, to make it functional. Then, as i was saying, when i run the power wire from that up to the front of the car, with a switch on it, before it reaches a "key-on" source.

Can someone hook me up with anything to tell me how to wire in the inertia switch and if ill need like a 2 prong or 3 prong toggle switch?


View attachment 389352

 

[BlownFiveLiter]

If you have all of the factory wiring in place yet, you could more than likely use it, right? Then it'd just be a matter of hitting the ignition hot lead to the relay to kill the fuel pump, and you could get away without running new wiring. Your inertia switch would still be functional that way, too. You really wouldn't need a three prong switch unless you want it to be lighted.

 

[Busted07]

If you have all of the factory wiring in place yet, you could more than likely use it, right? Then it'd just be a matter of hitting the ignition hot lead to the relay to kill the fuel pump, and you could get away without running new wiring. Your inertia switch would still be functional that way, too. You really wouldn't need a three prong switch unless you want it to be lighted.

I do still have all the factory wiring, but i didnt know if i could use that since the ECM is gone... i just didnt know if it ran through the ECM or not.

So could i just figure out which wire in that harness is the power wire, and splice it in there?

 

[Aryan15]

I would use the original wiring and the relay. Just cut the tan/light green wire going to the computer ground, and splice in your toggle switch. This will switch the control side of the fuel pump relay. Also make sure the red wire going to the inertia switch is fused constant 12V.

 

[Aryan15]

This should help.
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

 

[HISSIN50]

Aryan proposes doing it how I would too. As he said, just find new FP relay-coil sources (since the hot for the relay used to come from the EEC relay, and the ground pulse came from the computer) and you should be good. The inertia switch and all that should still function.
Good luck.

 

[jrichker]

For purposes of this thread, I already gave him a diagram and parts list. He said it was too complicated...

 

[HISSIN50]

Joe, I have the feeling that your very professional diagrams sometimes are a little tough for some people to follow.

It's one of those things where if he lived close, you could show him how it would be (mock the components up on the workbench) in two minutes. Absent that, the schematic is just intimidating.

FBD, we are all available (and I betcha' that Joe would be first to assist) to help with answering questions (perhaps having someone say to put relay terminal 85 to ground, Terminal 86 to the red/lt grn ignition switch wire.............. and so on, would help).

Good luck.

 

[Aryan15]

Is that surge dampner diode act like a capacitor to lighten the initial load on the pump?

 

[jrichker]

Is that surge dampner diode act like a capacitor to lighten the initial load on the pump?

No, it absorbs the spike generated when you turn the pump off. Anytime you open the circuit on an inductive load (coil, solenoid, motor, etc) it creates an electrical spike opposite in polarity to the voltage applied to it. The spike has to go somewhere, so the diode clamps it to ground.


HISSIN50 is right about the diagram, it does need the connection numbers on the relay to make it easier to read. Something else I need to fix...

 

[Busted07]

Ok, for some reason that must be the link that wouldnt open that you sent to me... this is the one that i got, and the reason i said it all looked like spaghetti.. The one you have up there is ALOT easier to understand... I saw this, printed it, took it out to my car, realized my eyes were bleeding, opened a beer, and set the schematic on the workbench.


View attachment 389209