Would this be a good kill switch?

[91Bomb]

I just did a fuel pump rewire and thinking about using a push button hazzard lights switch I have from my old car and splicing into the heavy 10 gauge wire from FP rewire and using that as an on/off kill switch. Does anyone see any reson why that might not be good? Of course I can go buy a heavy duty on/off switch at radio shack but like the action of this hazzard button switch and would rather use what I have.

 

[steve]

I recommend putting the switch in the ground side of the relay coil but the old power feed that you use to run the relay coil will work too and it's already in the dash area. Very little current flows so just about any switch will work. Putting the switch in the power feed for the pump isn't any more secure, both switches can be simply bypassed if the person knows where it is. Using the low current switching circuit is the better way to do it.

Note- I'm talking about putting the switch in the ground or trigger feed of the relay used during the rewire.

 

[91Bomb]

Well I would be going on the premise that if someone broke the ignition and got car to crank but not start they would give up not knowing why. Am I not thinking correctly about this?

I have a factory service manual so you're saying to locate the ?relay coil? to put kill switch in?

The only reason I thought about splicing into the 10 gauge wire from the FP rewire job is because it's routed right where I want to hide my kill switch. If you're saying this is no good and to splice into the relay tho please elaborate a bit more so i can do that. Thanks

 

[91Bomb]

I recommend putting the switch in the ground side of the relay coil but the old power feed that you use to run the relay coil will work too and it's already in the dash area.


Note- I'm talking about putting the switch in the ground or trigger feed of the relay used during the rewire.

I'm a bit confused. Is it in the dash area and exactly what should I be doing? I have factory service manuals and want to hook the kill switch into something low voltage like you were saying.


BTW is using that spare hazzard lights switch i have ok?

 

[HIGHPSI4]

I used a switch to break the ground for the fuel pump and put the switch at the bottom of the console behind the pass seat. I used a double pole switch and hooked the other pole to a LED mounted at the shifter. When the ground is broken to the pump the LED turns on.

 

[steve]

I'm a bit confused. Is it in the dash area and exactly what should I be doing? I have factory service manuals and want to hook the kill switch into something low voltage like you were saying.

When you did the rewire you used the old power feed for the pump to be the trigger wire for the new relay. It runs to one of the relay coil terminals and the other runs to ground. If you interrupt either side of the relay coil with a switch the relay will no longer activate and the pump won't run. The trigger wire comes frol the MPI relay in the center console which make it's easier to tie the switch into if you want it in the dash area.

The relay coil only uses a couple hundred milliamps when it's powered so the switch only have to carry that current when closed. A fuel pump can take up to 20 A when it's running so any switch used has to carry that current if you put the switch in it's power or ground wiring.

 

[91Bomb]

Ok thanks. So splice into one of the wires going to the mpi relay? I was going to do that awhile back but after not being able to get my hands in there I gave up. I was able to unbolt the mpi relay + unplug it but couldn't get my hands in there to cut + splice into the wires. Any tips on accessing those wires?

 

[steve]

The wire that was the fuel pump power coming out of the MPI relay. The black with green stripe in particular.

 

[91Bomb]

The wire that was the fuel pump power coming out of the MPI relay. The black with green stripe in particular.

Thanks, I'm going to hook in there