maw455

I need some advice on installing ignition and fuel pump cut-off switches in my track car. The car is a 1997 chassis with a heavily modded LS6. The electrical system (wiring harness, ECM, etc.) is all stock. I already have a master cut-off switch mounted on passenger side of the car near the A-pillar (battery is re-located to rear). On my side of the car, I can simply turn the key off to shut everything off in an emergency. However, I am currently installing a dry sump system, and want to be able to crank the motor to prime the oil system before start-up without the motor firing or dumping unburnt fuel into the cylinders. I would also like to have a backup to shut off the ignition and fuel in an emergency should the (original '97) ignition switch malfunction (I can't reach the master cut-off switch while strapped in).

I don't currently have a shop manual for this car, so I'm hoping someone here can help. Here are my questions:

1. Ignition and fuel injector cut-off

I'm guessing that the easiest and most reliable way to cut-off both the ignition system and the fuel injectors would be to interrupt the grounds to those circuits. Do they share a common ground? If so, is the ground on the chassis or the block and which one is it? Any concern about a longer path to ground (via cockpit switch) effecting the current draw of these circuits?

If cutting the ground(s) won't work or isn't the best solution, I assume that leaves cutting the power to the ignition relay, which I believe is #42. Does that relay control power to both the coils and the injectors? I assume cutting the power to the relay itself, rather than the power from the relay to the ignition, is the better way (lower amps), but how do I determine which is the correct lead on the relay?

2. Fuel pump - My understanding is the ground for the fuel pump is located on the frame rail inside the driver's side rear wheel well. I could simply re-route the ground from the frame rail to a cockpit switch and then to an alternate ground, but I have a concern about that potentially effecting the current draw across the pump motor due to slight resistance increase from the longer ground lead (I could be wrong though). The fuel pump is OEM and currently supplies adequate pressure for the larger fuel injectors I'm running, but don't want to slow the pump down any. I'm guessing it would probably be easier to interrupt the power between the engine bay fuse block and the fuel pump, either at the fuel pump fuse #13 or the fuel pump relay #35. Which is the best way to go?

Thanks in advance.

Lothar34

I believe that if you hold the accelerator to the floor and crank the engine, it will automatically cut the fuel feed. I know my Crown Vic won't start like that and I was told the Vette was the same way, though I haven't tested it.

That'd solve your priming problem pretty easily.