i just put a new engine in my 86 iroc, not using the comp anymore. now when i turn the car off it runs normal for 3 to 5 seconds then quits running . any ideas as to why its doing this.

 

Not using the comp. anymore? What type of ignition are you using then, an aftermarket stand-alone distributer? Also what about the wiring for your cooling fan? I know it may sound funny, but if you have the cooling fan hot-wired, and it's running when you power down, the fan will act like a generator and the ignition can still run on for a few seconds until the fan idles down.

 

It sounds like there is a back feed from a accesory part like the cooling fan thatcamaro69 mentioned if you have a electric water pump or have crossed the wires for the fuel pump either way it is providing power to the coil when the ignition is off