Atmospheric Leak Check
WARNING: This page does not describe the selected car, but rather 124 other vehicles, including the 1991 Chevrolet Pickup, 1991 Chevrolet Cab & Chassis, 1988 GMC Vandura Special, 1988 GMC Vandura, and 1988 GMC Value Van. However, it is still accessible from the selected car via links, so may be relevant.
Apply soap bubble solution to vacuum connector pipe seam (crimped upper-to-lower housing seam). Use a hose and blow air pressure into vacuum pipe and check for leaks. If leaks are present, replace modulator.
CAUTION:
Air pressure over 6 psi (.4 kg/cm2
) may damage modulator.