GM-GMC: Starting Problem, engine cranks, pink wire

Question
1987 Sierra
One day it will start fine, next time you go to start it the fuel gauge goes to the right past full and it will crank, but will not start.  Replaced starter, plugs, wires and coil.  What else can it be.  
Thanks,
Krista

Answer
Sounds like a short, a broken wire, or maybe a bad ignition switch.

Using a voltmeter or test light, check for +12 Volts at the pink wire that connects to the distributor, with the key in "Run" and "Start" positions.  Voltage should be present in both key positions, but will be less as the engine cranks.

No voltage?  This means that there is a problem in the wiring and/or ignition switch.  Try "hot wiring" +12 Volts to the terminal on the distributor where the pink wire connects and see if the engine will start.  Note that you will have to disconnect the "hot wire" to stop the engine if it starts (the ignition key will not stop the engine with the "hot wire" in place).

The ignition switch sits on top of the steering column near the point where it goes through the firewall.  The column mounts must be removed and the column allowed to drop down to replace the switch and/or to get to the other end of the pink wire.  The column does not need to be removed to reach the switch.