Mr Blonde, the purple wire is a saftey (for manual Tranny)used on the emergency brake switch so that the timer will not run the engine unless the emergency brake is set. On automatics, you need to ground the purple wire to a good ground. The fact that the timer times but the engine does not run leads me to believe that the purple wire ground is either missing or possibly a bad connection. Insure that the connector in the back of the timer unit has not backed out. This can sometimes happen when placing the unit under the dash. Also ground it to the same fusebox attach screw as the other grounds, because the timer unit itself works you know that that this ground is acceptable. Hope this helps, and good luck.
Alan