from tbi. when i turn car off now , it does not turn off immediately. it runs for about 30 seconds after switch is turned off then slowly dies. it is not "running on" it is like the switch is not turned off. what could cause this?

 

It's called "dieseling" and it's usually because the idle is set too high, or your idle A/F ratio is not set correctly. What is your idle set at ? 30 seconds seems like a WHOLE lot.

 

It could also mean your distributor is advanced too far. Retard it a few degrees and see if that stops it.

 

it's not dieseling. the switch is not immediately turning the car off. it's not dieseling at all.

 

I'm not sure what, but you must have screwed up something in the wiring. Check the wire going to the batt terminal on the distributer, I'll bet you it's hot even when the key is turned off. It shouldn't be. Check that and trace the problem from there.

 

I HAD THIS EXACT SAME PROBLEM! When I converted to carb I wired my cooling fans directly to the ignition. Everytime I'd turn my car off the fan motors would generate power and feed it back to the ignition. The power would slowly dim out as the cooling fan motor came to a stop and the car would die.

Hook anything that could be doing that up to relays.