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.
1987 Chevrolet Hi-Cube 6.2 J, 400/M40FACTORY OEM SERVICE PROCEDURE
Possible Cause & Correction
- Check EGR operation for being open at all times. See EGR SYSTEM CHECK chart in the TBI TESTS/CODES article in this section.
- Check output voltage of ignition coil.
- Check for crossfire between spark plugs (distributor cap, plug wires, and proper routing of plug wires).
- Check for intermittent condition in primary ignition system.
- Check ignition timing.
- Check for faulty spark plugs, plug wires and/or plug boots.
- Check for proper valve timing.
- Check engine compression (leaking or sticking valves).
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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