Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Spark Control System: Description
Ignition control system is designed to reduce emissions throughout all engine operating ranges by controlling ignition timing. System consists of a vacuum advance control unit, distributor, thermo vacuum valve (On fuel injected models), sub-advance control solenoid valve (On Federal 2WD and Calif. carbureted models), restrictive orifice (On fuel injected models), check valve (Turbo models) and vacuum lines. The thermo vacuum valve also operates canister purge system.
A dual-diaphragm (main and sub-advancer) type vacuum controller is used on Federal 2WD and Calif. carbureted models, and Fuel Injected non-Turbo models. A single diaphragm (advancer) type vacuum controller is used on Federal 4WD and Fuel Injected Turbo models.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.