1. Check the obvious (easy and cheap first):
* Ignition Switch: Try turning the key all the way to "start" and listen for the click of the solenoid engaging the starter. If you don't hear it (or hear a weak click), the ignition switch might be faulty and not sending power to the rest of the system. A helper turning the key while you check power at the ignition coil is helpful here.
* Battery and Cables: Test the battery voltage. It should be around 12.6V when not running. Check the battery terminals and cables for corrosion and tightness. Clean them if necessary. A weak battery or poor connections can prevent sufficient current flow.
* Fuses: Check the fuse box (usually under the dash or in the engine bay) for any blown fuses related to the ignition system. Consult your owner's manual to identify the correct fuses.
2. Ignition System Components (more involved):
The ignition system in your van likely consists of:
* Ignition Coil: This boosts the 12V battery voltage to the high voltage needed for sparking. You can test it with a multimeter for continuity (resistance) and visually inspect it for cracks or damage.
* Distributor: This is the heart of your ignition system. It's responsible for distributing the high voltage to the correct spark plug at the right time. Inside, there's a rotor, cap, and points (or an ignition module depending on the exact setup of your van).
* Ignition Module (or Points): These control the timing of the spark. If it's points, check their gap and condition. If it uses an electronic ignition module, testing it is more involved and might require a diagnostic tool or replacement.
* Pick-up Coil (in distributor): This sensor in the distributor detects the crankshaft position and sends a signal to the ignition module.
* Wires: Check all the wiring between the components for any breaks, shorts, or loose connections. Look particularly at the wires coming from the coil, to the distributor, and to the spark plugs.
3. Testing Procedures (requires multimeter):
* Coil Test: With the ignition key ON, measure the voltage across the coil's primary terminals (the smaller ones). You should read battery voltage (12V). Measure resistance across the primary and secondary windings (using the correct ohm scale on your meter - consult your multimeter instructions and a wiring diagram for your van's specific coil).
* Power to Coil: With the key ON, measure the voltage going to the positive (+) side of the coil.
* Distributor Cap and Rotor: Inspect for cracks, burns, or excessive wear on the distributor cap and rotor. Replace if necessary.
* Spark Plug Wires: Check for cracks or damage in the spark plug wires. A bad wire can cause misfires or no spark.
4. Troubleshooting Steps:
1. Start with the easiest: Check the battery, cables, fuses, and ignition switch.
2. Visual inspection: Carefully examine all components of the ignition system for any obvious problems (damage, corrosion, loose connections).
3. Testing: Use a multimeter to test the coil, ignition module, and wiring for proper voltage and continuity.
4. Seek professional help: If you are not comfortable working on the electrical system of your vehicle, take it to a qualified mechanic. Improper testing or repair can be dangerous.
Important Notes:
* Safety First: Disconnect the negative (-) battery cable before working on any part of the electrical system.
* Wiring Diagram: Obtain a wiring diagram specific to your 1986 GMC Safari van. This will be invaluable in tracing the circuits and identifying the correct components and their connections. You can usually find this online or through a repair manual.
By following these steps methodically, you should be able to pinpoint the cause of the lack of spark in your GMC Safari. Remember to always prioritize safety.
