Confused, I need help on different fuel pump wiring methods.

[5.0 Fiend]

Confused, what is best way to wire up in-line fuel pump?

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My 88 cougar motor to 84 stang body is pretty much complete, I just have to figure out how to wire up the fuel pump. Since the 84 motor had a mech. pump, and I got a deal on a Holley Red in-line pump, I decided to put that on, (thought it would be easier). I need a quick crash course on different wiring methods for the fuel pump, i.e., relay's, fuses, I am pretty much a moron come wiring time, so I need to figure out what to buy.
I figure this is how it could be set up the easiest. Black wire goes to frame ground, and the red wire coming from the fuel pump could go through a 30 amp in-line fuse(too big? too small?), into a switch that I have on my dash panel, that is connected to a hot wire, I figure 14 gauge wire would work? Did i get the just of how to wire up the pump? How does the relay type wiring work? (I tried reading my haynes manual to get an idea on how to wire up a relay, but there were too many wires, why would you need that many just to get a hot wire to the pump?) I would also like to know how to wire up a fuel pump relay, just in case I decide, ot have to go that route, so please be descriptive as possible.
That is why I figure having one wire going through an inline fuse to a switched on hot source would be the easiest for me. Sorry if I sound like a wiring idiot, but it is because I am, any help would be greatly appreciated, thanks.

[5.0 Fiend]

Okay, I think I may have just figured it out. I did a search, and the only reason I see for having a relay, is because it hooks the pump in to something called an Inertia switch, which if I am correct, shuts the fuel system off if you are hit hard, correct? Since my car had a mechanical fuel pump before, it would not have an inertia switch, so I could just run the red wire from the pump through an in line fuse, to a power source?
I also have another question yet again, what is the easiest way to run the power wire from the pump to the dash? Through the hatchback area somehow? Through the floorpan? Where is a good place to hook into the ignition circuit instead of a switch? Off of the hot wire going to the ignition coil? The pump has to be powered in the start and run posistion, and the coil hot wire is powered in the start and run posistions right?

[andy669]

I take it you are putting a carb on your cougar motor?

You should always wire fuel pumps through a relay.

Andy

[5.0 Fiend]

Yeah, I had a Holley carb and intake on my 84, and I like my toys to have carbs, (a lot easier to work on for me). Why do you need a relay exactly? How would I wire it up since I dont have an inertia switch? Would the red wire from the pump go to one side of the relay, while the switched on hot wire went to the other side?

[andy669]

A relay is installed to keep a more consistant voltage at the pump. It also eliminates the need for a heavy duty switch.

The relay will have 5 terminals, you will use 4 of them. 2 are the coil inside the relay. 1 of those will go to ground, the other will go to key on power. You can use light wire for these. 14-16ga will be enough. 1 of the terminals will go directly to battery power, and the other will go to the pump. For a Holley red, 12 gauge will probably be big enough to go to the battery, and the pump. I have several relays at the shop, and I can tell you which numbers go where after I look at one.

If I had to recall from memory which terminals would go where, it would go like this. 83 and 85 are the coil. When key on power is supplied, the coil is energized and pulls in a magnet which sends power from 87 (battery) to 87a (fuel pump).

You can get this relay at O'reillys or just about any other parts store. I'll double check the numbers today and post again.

Andy

[5.0 Fiend]

Oh, I though there was only 2. Let me see if I have this straight. One wire goes to the battery for your power, one wire is for the relay ground, one wire goes to a switched on power source, and when that wire gets grounded it closes the circuit in the relay which sends battery power to the last wire which is connected to the pump? Where is a good place to hook into the switched on power from the ignition switch? The positive wire going to the ignition coil? Where is a good place to mount the relay?

[79Stang351W]

On my carbed 79 Coupe with 351W, I ran a Mallory Comp 140 with 1/2 in. lines and a 1/2 in. return. I used a Radio Shack 30 amp relay. I also picked up a socket that fits onto the relay with wires for splicing into. I mounted the relay inside the trunk on the spare tire well. I drilled a hole in the sparetire well to put the wires through and put a rubber grommet in the hole to protect the wires. I used 10 gauge wire for power supply and ground, and 12 guage for the switch. Anywho, on the specific relay I used, Radio shack 30 amp, connect as follows:

86 - power switch: 12 guage wire to your on/off switch (You can connect into your ingnition switch wires, but I just used a 30 amp double pull on/off switch and ran it to the battery connection on the solenoid. I wanted to be able to shut off the pump and let the engine run to drain the bowls for jet changes.) Note: I also used an inline cylinder type 7.5 amp fuse for this switch.

85 - Ground. 10 guage wire to frame in rear. Two wires, ground wire from the relay and ground from the pump connected to the ten guage wire then to the frame.

87 - Power: 10 guage wire from positive side of battery with heavy duty cylinder type fuse (7.5 amp fuse which came with the pump) to 87 terminal on relay.

30 - Power: Power side directly to pump.

Runs great! I went with the heavier wire so I wouldn't get a voltage drop from the smaller guage wire running all the way back to the pump.
Good luck,
MIKE

[~The Jester~]

We just went over this on my website.


Electricity

[5.0 Fiend]

The other day I bought a 30 amp relay, 20 feet of 12 gauge for the battery wire, a spool of 16 gauge for everything else, covuluted plastic wire tubing, and a 120 piece wire connection kit. I bought more than I needed, because I will probably be installing some woofers in the near future. Hopefully it wont be as hard as I think it will be.

[5.0 Fiend]

If I were to mount the relay in the hatch area, would 12 gauge wire be big enough to run the whole way up to the battery? I was thinking about putting it by the drivers seat, kind like a half way point, any good ideas on how to route the wiring up to there? Up through the spare tire well, then down into the kick panel? Come to think of it, I think there is a wire already back in the hatch, I think the previous owner had a sound system.

[Ieatcamaros]

12 gauge wire is fine.

[PKRWUD]

This might help...

[ultraflo]

The numbers on the bottom of the relay that Andy is referring to are as follows:

30 -- to +12v batt. source
85 -- to ground
86 -- to toggle switch
87 -- to pump

You should maybe step up to at least 10g wire if you have to go some distance... putting the relay under the dash should be okay, with the bigger wire. And you can easliy route the wiring inside the interior, out through a grommeted hole near the pump.


The 'dashes' located around the numbers below represent what the bottom view of the relay should look like:

....87_
..87A_
86| .... |85
....30|