Fuel pump kill switch
Fuel pump kill switch Im going to put in a kill switch for my fuel pump. I suppose more than a few times I or someone else will try to start the car without turning the switch on, can that hurt anything?
I want to use a normally open momentary switch. That way I just press and hold the switch, start the car, and release the switch. No need to press the switch again when I shut off the car. How do I wire this up, I tried to figure it out with some relays but couldnt?
Im also going to have a "valet switch" so I can disable the kill switch when I take the car in to have work done....a toggle switch in parallel with the kill switch should accomplish that.
I want to use a normally open momentary switch. That way I just press and hold the switch, start the car, and release the switch. No need to press the switch again when I shut off the car. How do I wire this up, I tried to figure it out with some relays but couldnt?
Im also going to have a "valet switch" so I can disable the kill switch when I take the car in to have work done....a toggle switch in parallel with the kill switch should accomplish that.
Originally Posted by nebur8
if you use a momentary switch wouldn't the fuel pump turn off when you let it go after the car is on? no fuel = stall?
Ideas anyone?
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
A momentary switch can be used with a "latching relay" to activate a circuit that will remain active until the power is removed. Your rear defogger is sort of a latching relay except that it also has a timer to shut it off. Pressing the defroster button activates the circuit and it stays on until the timer shuts it off (or you turn off the car).
Here is a thread that shows how to make your own latching relay from an ordinary automotive "Bosch" style relay and a diode: https://ls1tech.com/forums/wiring-stereo-electronics/681569-switch.html
You would put the latching relay inline in the fuel pump relay circuit. Use an ignition controlled power source (so that it will shut off when you turn off the ignition) and use your push button to latch the relay. You would have to turn on the ignition then press your button to activate the fuel pump before you could start the car.
Using an extra factory ASR switch (TCS switch on Firebird) would be a good way to hide its function. You would have to be sure to hide your "valet" toggle switch someplace that isn't obvious or even easily accessible.
Here is a thread that shows how to make your own latching relay from an ordinary automotive "Bosch" style relay and a diode: https://ls1tech.com/forums/wiring-stereo-electronics/681569-switch.html
You would put the latching relay inline in the fuel pump relay circuit. Use an ignition controlled power source (so that it will shut off when you turn off the ignition) and use your push button to latch the relay. You would have to turn on the ignition then press your button to activate the fuel pump before you could start the car.
Using an extra factory ASR switch (TCS switch on Firebird) would be a good way to hide its function. You would have to be sure to hide your "valet" toggle switch someplace that isn't obvious or even easily accessible.
Thanks! This is just what I was looking for.
So I could even hook up the kill switch to whatever is turned on when the unlock button on my key fob is pressed(interior lights come on). Then when I get in the car I can press the kill switch, put the key in and start the motor.
Originally Posted by WhiteBird00
You would put the latching relay inline in the fuel pump relay circuit. Use an ignition controlled power source (so that it will shut off when you turn off the ignition) and use your push button to latch the relay. You would have to turn on the ignition then press your button to activate the fuel pump before you could start the car.
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Originally Posted by NoTicketsPlease
Thanks! This is just what I was looking for.
So I could even hook up the kill switch to whatever is turned on when the unlock button on my key fob is pressed(interior lights come on). Then when I get in the car I can press the kill switch, put the key in and start the motor.
So I could even hook up the kill switch to whatever is turned on when the unlock button on my key fob is pressed(interior lights come on). Then when I get in the car I can press the kill switch, put the key in and start the motor.
Trending Topics
Originally Posted by WhiteBird00
You mean have your pushbutton get power from the courtesy lights so that you could only activate the fuel system when they were on (such as right after getting in the car)? Yes, you could do that but it might have undesirable consequences. For example, if you were sitting in your car waiting for someone, you would have to open the door (or do something else to make the courtesy lights come on) before pressing the kill button in order to start the car.
Good thinking, ill just wire up the kill switch in parallel with courtesy lights and ignigtion on
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Originally Posted by LT1wannabe
Newbie question...why? I apologize for my ignorance. lol
Originally Posted by daniel6718
the wire and relay for the fuel pump is by yourt left foot under the door trim panel...put a on off switch in the ground for the relay
Which wire is it? There are two orange 14 or 12 guage wires that run to the back of the car along the drivers seat. I used my wire finder hooked up to the fuel pump relay and it seems to be these wires, but my diagram says it should be grey.
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
You want to interrupt the fuel pump power on the coil (low voltage) side of the fuel pump relay not on the actual fuel pump power wire. It's safer and it's also easier to fix should your relay fail for some reason. You can put it in the relay coil power wire (dark green with white) or on the ground side (black with white). The power side will be easier because you can get it at the PCM and run through the grommet below the PCM into the car for your switch. The dark green with white wire is in position 9 of the red connector on the PCM.
If you really want to use the fuel pump power lead, the easiest place to get it is at the large 48-pin inline connector under the dash to the left of the steering column. It's the gray wire along the outside edge between a dark green wire and a black wire. There is another gray wire on the opposite edge of the connector but it doesn't have any wires beside it.
If you really want to use the fuel pump power lead, the easiest place to get it is at the large 48-pin inline connector under the dash to the left of the steering column. It's the gray wire along the outside edge between a dark green wire and a black wire. There is another gray wire on the opposite edge of the connector but it doesn't have any wires beside it.
Originally Posted by WhiteBird00
You want to interrupt the fuel pump power on the coil (low voltage) side of the fuel pump relay not on the actual fuel pump power wire. It's safer and it's also easier to fix should your relay fail for some reason. You can put it in the relay coil power wire (dark green with white) or on the ground side (black with white). The power side will be easier because you can get it at the PCM and run through the grommet below the PCM into the car for your switch. The dark green with white wire is in position 9 of the red connector on the PCM.
If you really want to use the fuel pump power lead, the easiest place to get it is at the large 48-pin inline connector under the dash to the left of the steering column. It's the gray wire along the outside edge between a dark green wire and a black wire. There is another gray wire on the opposite edge of the connector but it doesn't have any wires beside it.
If you really want to use the fuel pump power lead, the easiest place to get it is at the large 48-pin inline connector under the dash to the left of the steering column. It's the gray wire along the outside edge between a dark green wire and a black wire. There is another gray wire on the opposite edge of the connector but it doesn't have any wires beside it.
Now I just need to find an ignition on wire(ie something that is powered when you turn the ignition to on). Where is one under the dash near the pedals? Also, how do you know where all these wire are???
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Originally Posted by NoTicketsPlease
Okay, im going to use the dark green with white wire on the relay coil side.
Now I just need to find an ignition on wire(ie something that is powered when you turn the ignition to on). Where is one under the dash near the pedals? Also, how do you know where all these wire are???
Now I just need to find an ignition on wire(ie something that is powered when you turn the ignition to on). Where is one under the dash near the pedals? Also, how do you know where all these wire are???
. (Actually, it's in the service manual.)There are numerous ignition controlled wires at the steering column but the best place to get power for accessories, etc. is one of the three special ports in the fuse panel provided for that purpose. They are single blade ports labeled BATT (constant battery power), IGN (ignition controlled power), and ACCY (ignition and RAP controlled power). They are each 15-amp circuits so be sure to add an inline fuse if that's too muchfor your wiring.
Originally Posted by WhiteBird00
Ancient Chinese secret...I could tell you but then I'd have to kill you . (Actually, it's in the service manual.)
There are numerous ignition controlled wires at the steering column but the best place to get power for accessories, etc. is one of the three special ports in the fuse panel provided for that purpose. They are single blade ports labeled BATT (constant battery power), IGN (ignition controlled power), and ACCY (ignition and RAP controlled power). They are each 15-amp circuits so be sure to add an inline fuse if that's too muchfor your wiring.
. (Actually, it's in the service manual.)There are numerous ignition controlled wires at the steering column but the best place to get power for accessories, etc. is one of the three special ports in the fuse panel provided for that purpose. They are single blade ports labeled BATT (constant battery power), IGN (ignition controlled power), and ACCY (ignition and RAP controlled power). They are each 15-amp circuits so be sure to add an inline fuse if that's too muchfor your wiring.
I had the latching relay working on the bench but in the car the fuel pump wire wasnt enough to keep the relay open. I guess I need to wire the ign on across the relay as well.
I installed a valet switch(actually just quick disconnects) so I am leaving that connected in the meantime.
Okay I made a diagram of what I did and what I plan to do. The red parts(click image to see them better) are what I plan to do, will it work? Im skeptical. Maybe I should use a different relay so it doesnt take as much to keep it open? Im using a 30amp auto relay currently. Or maybe 2 relays.
Also, should I use fuses, what kind and where? I dont want to fry my pcm.
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Sorry...missed your earlier post. Give me a little while to look at it and perhaps come up with a schematic. I'm not usually on here on weekends so it might be Monday.
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
I'm a little concerned about connecting an ignition power source to the fuel pump control wire from the PCM. What about using two relays? Wire the first as a latching relay like in the diagram but with ignition controlled power output to be used as the coil supply of the second relay. Then you can just use the second relay 30/87 terminals as a simple cutoff for the fuel pump relay control wire.