Deceleration Valve
- Remove air cleaner. Plug air cleaner vacuum source. Connect tachometer. With engine running at specified idle speed, remove small deceleration valve signal hose from manifold vacuum source. Reconnect signal hose and listen for air flow through ventilation pipe and into deceleration valve. A drop in engine RPM will be noticed when signal hose is reconnected.
- If air flow does not continue for at least one second or engine RPM does not drop noticeably, check deceleration valve hoses for restrictions or leaks. If no restrictions or leaks are found, replace deceleration valve. See Figure
, Figure
and Figure
.
Courtesy of GENERAL MOTORS CORP.