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.
1983 GMC Forward Control 5.7 M, StandardFACTORY OEM SERVICE PROCEDURE
Intermittent System Problems
- Using a spark tester or modified spark plug, check for spark at 2 spark plug wires. If no spark results, see System Testing. If spark is noted on one or both wires, check for dwell increase from low to high RPM.
- Check pick-up coil with ohmmeter leads attached to Green and White wires, removed from HEI module. If reading does not indicate between 500-1500 ohms, replace pick-up coil. If pick-up coil reading was satisfactory, and dwell did not increase, replace electronic module.
- If pick-up coil was satisfactory, but dwell increased, check fuel, spark plug wires, distributor cap, rotor or spark plugs.
Factory Service Tools
Use the Manual With the Right Hardware
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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.
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