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.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET1985CHEVY VAN G20, 6.2 C, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 10 (ENGINE CONTROLS - TESTS W/O CODES - GASOLINE)SYMPTOMSENGINE BACKFIRESSYMPTOM DEFINITION
1985 Chevrolet Chevy Van G20, 6.2 C, Standard
Symptom Definition
1985 Chevrolet Chevy Van G20, 6.2 C, StandardSECTION Symptom Definition
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Vandura Special, 1994 GMC Vandura, 1994 GMC Rally Camper Special, 1994 GMC Rally, and 1994 GMC Forward Control. However, it is still accessible from the selected car via links, so may be relevant.
Fuel ignites in intake manifold or in exhaust system, making a loud popping noise.
Possible Causes & Corrections:
- Ensure EGR valve is not always open.
- Check engine for sticking or leaking valves.
- Check for proper valve timing.
- Check for engine vacuum leaks. Ensure engine is tuned to specifications.
- Using Spark Tester (ST-125), check available output voltage of ignition coil.
- Check for crossfire between spark plugs, distributor cap and spark plug wires.
- Check for an intermittent ignition system problem.
- Check for erratic spark timing or distributor reference (RPM) signal.
- Ensure initial ignition timing is properly set.
- On some 5.7L engines, check for faulty air injection diverter valve or check valve.
- Check for fuel or water in vacuum hose to MAP sensor. Also check for restricted hose.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.