Is there a good spot for keyed power under the hood?

[cbrown5385]

Good afternoon everyone. Is there’s a decent spot for keyed power under the hood, instead of running back into the cab fuse block?

 

[75gmck25]

Are you going to use a relay, or provide direct power to something? Wipers circuit provides keyed power, and so does the electric choke, but they don’t handle a lot of amperage.

 

[dsteelejr]

A little more info would be helpful, like what type of device you need to power because the power demand is going to determine how you wire it up. Like @75gmck25 said, those circuits are not meant for high amperage, you may be better off using a relay. Regardless of how you do it, don’t take power from the distributor / coil power wire.

 

[Matt69olds]

Get a fuse box of your choice, use a relay to power the fuse box from a fusible link connected to the battery. Use the wiper power feed, HEI power wire, or an unused ignition power port on the original fuse box to trigger the relay.

 

[Turbo4whl]

Another way to switch on power under the hood without going through the firewall, pressure switch plumped to the engine oil feed. Fused feed from the battery to the pressure switch. Wire back to a relay to power up your accessory. This is how I wired up my air horn compressor. Will only run when the engine is running.

 

[cbrown5385]

I’m wiring the ACE’s efi kit. It supplies a super small 18 guage wire that I’m thinking powers a relay in the system with the wiring being that small and there being larger 12 gauge wire. This is a whole kit with fuses and relays already in line. Sorry I wasn’t even thinking of putting that in their… I work midnights so being out in the sun to long messes me all up

 

[Ricko1966]

If you trigger the relay from the alternator exciter wire the pump will only run with engine running

 

[dsteelejr]

Since you’re going EFI you won’t need a choke. Is there a choke wire available? I don’t know anything about your set up, how stock or modified or hacked up it is by POs, but factory wiring had the choke powered with key on AND through the oil pressure switch so it only sent power to the choke when there was oil pressure. Take the choke wire that comes out of the bulk head connector and splice onto it.

 

[CalSgt]

Whatever wire you choose test it to be certain it provides power with key in the “run” position and in the “start” position.

The ignition switch is designed to cut power to several circuits while cranking…

 

[Ricko1966]

I wrote this for another member about a week ago,the text is screenshots in the thumbnail. If the diode part confuses you( no insult meant) I can write it using 2 relays one in crank position one in run position. Ans easy safe way to wire up an electric fuel pump.

 

[AuroraGirl]

If you trigger the relay from the alternator exciter wire the pump will only run with engine running

Wont the alternator exciter wire be resisted ignition when the key is in on, not crank ofc?

because the it provides that key on, and once the engine is running the alternator outputs the full running voltage and that turns off the light since there is no longer a ground on the light bulb

 

[Ricko1966]

Wont the alternator exciter wire be resisted ignition when the key is in on, not crank ofc?

because the it provides that key on, and once the engine is running the alternator outputs the full running voltage and that turns off the light since there is no longer a ground on the light bulb

There will be a constant signal from the alternator exciter wire,keeping the relay closed,keeping the fuel pump running.

 

[AuroraGirl]

There will be a constant signal from the alternator exciter wire,keeping the relay closed,keeping the fuel pump running.

I didnt realize he had a 1990 , so you mean to piggyback the wire for the fuel pump on the truck already?

He could also tie into the failsafe that lets the truck keep running through the oil pressure that TBI has

 

[dsteelejr]

I didnt realize he had a 1990 , so you mean to piggyback the wire for the fuel pump on the truck already?

He could also tie into the failsafe that lets the truck keep running through the oil pressure that TBI has

Was just rereading through some older posts I commented on, including this one, and I didn’t realize it was a ‘90 until I saw you say this just now. And I was talking about splicing into the choke wire ‍[face palm and sigh]