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HOMESERVICE MANUALSCHEVROLET1997CHEVY EXPRESS G3500, VAN CARGO, 6.5 FREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 10 (ENGINE CONTROLS - TESTS W/O CODES - 7.4L (G SERIES))SYMPTOMSLACK OF POWER OR SLUGGISHPOSSIBLE CAUSES & CORRECTIONS
1997 Chevrolet Chevy Express G3500, Van Cargo, 6.5 F

Possible Causes & Corrections

1997 Chevrolet Chevy Express G3500, Van Cargo, 6.5 FSECTION Possible Causes & Corrections
WARNING: This page is about a different variant/trim than selected.
  • Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter. See EXHAUST SYSTEM BACKPRESSURE under MECHANICAL INSPECTION in the BASIC TESTING - 7.4L article.
  • Check engine valve timing and compression.
  • Check engine for a worn camshaft.
  • Check TCC system for proper operation.
  • Check transmission shift pattern and downshift operation.
  • Using Spark Tester (J-26792), check for adequate spark output.
  • Ensure correct initial ignition timing.
  • Check ESC system for excessive retard.
  • Check EST system for proper operation.
  • Check air filter and fuel filter. Replace if necessary.
  • Ensure fuel system pressure is correct at all engine speeds.
  • Check for poor fuel quality or water-contaminated fuel.
  • Check injector wires for short to ground at air cleaner.
  • Check for spray from one injector on TBI unit. Malfunction may be present in injector assembly or in signal to injector assembly. Isolate malfunction by switching injector connectors. If problem remains with original injector, injector is defective. If malfunction moves with injector connector, problem is an improper signal in injector circuits.
  • Check PCM grounds. Ensure they are clean, tight and properly located.
  • Ensure EGR valve is not always open.
  • Check charging system output. Repair if output is less than 9 volts or greater than 16 volts.
  • Check A/C for proper operation.
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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.