Vacuum Regulator Valve (Diesel Models Only)
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.
- Attach vacuum regulator valve to fuel injection pump. Valve body must be securely attached but free to rotate on pump. Attach vacuum source of 9.0-10.4 psi (.6-.7 kg/cm2 ) to bottom vacuum nipple. Attach vacuum gauge to upper nipple.
- Insert vacuum regulator gauge bar between gauge boss on injection pump and wide open stop screw on throttle lever. Rotate throttle shaft and hold lever against gauge bar. Slowly rotate vacuum regulator valve body clockwise.
- Setting will only be valid if performed with clockwise rotation. When vacuum gauge reads 5.3-5.9 psi (.37-.41 kg/cm2 ), tighten valve body mounting screws. Check setting by releasing throttle lever to idle stop position.
- Rotate throttle shaft back until lever rests against gauge bar again. Check vacuum gauge reading and ensure it is still 5.3-5.9 psi (.37-.41 kg/cm2 ). If not to specification, reset valve and check setting again.