LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1988 >> Forward Control 5.7 M, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Air Injection System >> Component Testing >> Air Pump
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Air Pump

Accelerate engine to approximately 1500 RPM and observe air flow from hose. If air flow increases as engine is accelerated, pump is okay. If air flow does not increase or is not present, check belt tension and for leaky pressure relief valve. Air may be heard leaking with pump running. Replace as necessary.