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 MANUALSCHEVROLET1987STEP VAN P20, 7.4 W, AUTOMATIC, 400/M40REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 14 (ENGINE CONTROLS - SYSTEM/COMPONENT TESTS - GASOLINE)EMISSION SYSTEMS & SUB-SYSTEMSAIR INJECTION (C-6)CHECK VALVE
1987 Chevrolet Step Van P20, 7.4 W, Automatic, 400/M40
Check Valve
1987 Chevrolet Step Van P20, 7.4 W, Automatic, 400/M40SECTION Check Valve
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Yukon, 1994 GMC Suburban, 1994 GMC Pickup, 1994 GMC Cab & Chassis, and 1994 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
Allow engine to cool. Remove check valve from engine and blow through valve in direction of check valve flow (to cylinder head). Attempt to suck back. Replace valve if airflow is allowed against the direction of flow.
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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.