keeps running

[mudmizer]

I moved the hot wire for the electric fan from one place on the fuse block to another. I don't recall which spade I plugged it into on the fuse block but now the truck won't turn off right away. Worked just fine before that. When I turn the ignition switch off the truck continues to run, not dieseling, it runs just as if I never turned the switch off. It runs for about 3-4 seconds and then shuts off nice and clean as if I then switched it off. I moved the fan wire because it kept blowing the fuse where it was after a few miles.
I guess I could wire the fan direct with it's own inline fuse.
Just wondering what may cause this.

Runs great, just I have to wait till it turns off to get out.

[steelhorse]

I may be overheating the circuit causing a power bleed.The real issue is that you need to run a relay with an electric fan or you will cook your wiring.There are many companies that make wiring harnesses for this relitively cheap and they are not that hard to install.

[sneakysnake]

Is your fan on a relay? it needs to be on a relay or the fan motor turns into a generator when turned off and back feeds the coil until it slows down enough to stop producing electricity.

[Longhorn Man]

snake hit the nail right on the head.
The fan spinning creates enough power to backfeed and fire the HEI.
You can either fix this with a diode in the power wire, or, a relay which would be better in many ways. The amps the fan pulls is more than the fuse box was designed to handle, so you are doing damage every time the fan kicks on. Run a relay from the battery, with the fuse box being the trigger, and the switch on the ground side of the relay from the fan sensor in the rad.
You'll be golden then.

[mudmizer]

Thanks guys. I've got a couple relays, I'll get one in. I had wondered a bit about the fan acting as a generator but figured it coulden't generate that much. I am running all MSD ignition.

[Longhorn Man]

it doesn't take much in all reality.