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.
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HOMESERVICE MANUALSCHEVROLET1987HI-CUBE 6.2 J, 400/M40REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMFUEL INJECTION SYSTEM - TBITROUBLE SHOOTINGSURGING
1987 Chevrolet Hi-Cube 6.2 J, 400/M40
Trouble Shooting: Surging
1987 Chevrolet Hi-Cube 6.2 J, 400/M40SECTION Surging
- Check EGR valve operation. See appropriate EGR SYSTEM CHECK chart in GENERAL MOTORS COMPUTER COMMAND CONTROL article in COMPUTERIZED ENGINE CONTROLS section.
- Check ignition timing. Check fuel filter for restrictions. Check fuel pressure. See FUEL SYSTEM PRESSURE TEST . Check alternator output voltage. Repair alternator if output voltage is less than 9 volts or more than 16 volts.
- Check Torque Converter Clutch (TCC) operation. See appropriate TORQUE CONVERTER CLUTCH ELECTRICAL DIAGNOSIS chart in GENERAL MOTORS COMPUTER COMMAND CONTROL article in COMPUTERIZED ENGINE CONTROLS section.
- Remove and inspect oxygen sensor for silicon contamination from fuel, or improper use of RTV sealant. Sensor may have a White, powdery coating and will result in a high, but false signal voltage (rich exhaust indication). Check ignition system.
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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.