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 MANUALSCHEVROLET1988STEP VAN P20, 7.4 W, AUTOMATIC, 475/M40REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISCCC TESTS W/O CODESDIESELING/RUN-ONPOSSIBLE CAUSE & CORRECTION
1988 Chevrolet Step Van P20, 7.4 W, Automatic, 475/M40
Possible Cause & Correction
1988 Chevrolet Step Van P20, 7.4 W, Automatic, 475/M40SECTION Possible Cause & Correction
- Check for leaking injectors: Apply 12 volts to fuel pump test terminal to turn fuel pump on and to pressurize system. See appropriate CHART A5 - FUEL PUMP RELAY CIRCUIT DIAGNOSIS chart in the TBI TESTS/CODES article in this section.
- Visually check injectors and TBI unit for leaks.
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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.