Another Centech wiring question

[JWMcCrary]

The Emissions wiring has CHOKE, IDOL SOL, and DIST MOD wires. I will use the choke wire on my carb. The other 2 wires are both powered 12V when the key is on(run). Those wires are a little small but since they are not needed I was thinking I could tie them together to power my 4070 electric fuel pump. Can't say for certain but I'm pretty sure these wires are on a 10 amp fuse labeled IGN 2. Any reason why I shouldn't do this. Trying not to run a bunch of extra wires if I don't have to. I have the fuel pump on a relay so those wires would be the 12V source on the relay as opposed to running a new wire to the battery.

 

[ObscureMachine]

Those wires are a little small but since they are not needed I was thinking I could tie them together to power my 4070 electric fuel pump.

Run the two wires to the relay? Or to the pump? The relay doesn't need two wires, and I wouldn't run two wires to power the pump. I would use one heavier wire from the relay to the pump.

If I'm understanding you correctly, which I might not be as I'm still on my first cup of coffee.

Side note, wire an inertia switch into your fuel pump wiring if you don't have one. The carter will just keep pumping fuel if you're in a wreck, which is a bad deal.

 

[JWMcCrary]

No your not completely understanding correctly. I will run a new wire from the relay to the pump. The wire controlling the relay goes thru a oil pressure switch, have run 4070 like that for years and works fine, no need for inertia switch. My concern was the smaller wires together providing the 12V to the relay that gets switched to the pump. I called Centech and they said it should be fine. They don't always answer but this time they did.

 

[DirtDonk]

The relay uses literally a miniscule amount of power to energize. Therefore either of those wires by themselves can be used to trigger the relay for the pump. What they should not be used for is as the battery source for the pump.
The wires are not only smaller than optimum for a pump located in the back of the truck by the tank(s), but you're then putting that extra load through the ignition switch. Which you do NOT want to do if you can avoid it. There are already enough very important circuits that use the ignition switch as their main source.

Use the Centech wires as Pin #85 then. And make your own 12-14ga wire to run from the battery to Pin #30 on the relay. And make your own to run from Pin #87 to the pump.

Well, that's the generic way anyway. With your oil pressure switch in the mix, those numbers might get mixed around some. Just make sure you do not have a direct line from the fuel pump to those listed Centech wires.
That way you don't have to worry about combining them, and you still have extras left over for other duties.

Paul

 

[JWMcCrary]

What they should not be used for is as the battery source for the pump.
The wires are not only smaller than optimum for a pump located in the back of the truck by the tank(s), but you're then putting that extra load through the ignition switch. Which you do NOT want to do if you can avoid it.

Paul

Well that was my question, and after thinking about it I have to agree. I didn't want to run another wire to the battery but That's what I will do. I was only thinking of the fuse and what would be on that circuit, hadn't thought about the ignition switch which is a valid point when you start adding things. Thanks Paul.

 

[DirtDonk]

What alternator are you running? If a high-output and you can't use the stock Centech Yellow charge wire anyway, many of us repurpose it to power a terminal strip, or aux fuse panel, or power stud. Can be just about any location you choose, but most often the most convenient is over by the passenger side fender skirt between the firewall and battery.
This way you have all the extra room you need for added wires without needing to connect them to either the battery or the starter relay stud.

Makes for a much cleaner and convenient way to run all those extra circuits we somehow manage to need.
Even if you are using the stock Yellow wire with a smaller alternator, you can still use the terminal strip/power stud idea. You just run a single 10ga or so wire to the stud, then all the other wires from there.
Auxiliary fuse boxes are just as convenient as studs too, but it depends on how you're laying out all the extra circuits.

Paul