TM-9-2815-220-24 Maintenance Manual for AVDS-1790-2CA AVDS-1790-DA and AVDS-1790-2DR Engines Download
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TM 9-2815-220-24 ENGINE NOISY OPERATION 0015 00 MALFUNCTION 2: Diesel knock ("ping," usually at low-idle speed). PROBABLE CAUSE CORRECTIVE ACTION a. Manifold heater solenoid valves defective. (1) Check solenoid operation as follows: PROCEDURE OBSERVATION ANALYSIS Evidence of action indicates normal solenoid valve operation. Press heater switch intermittently "ON" and "OFF". Note audible "click" or opening and closing valve action (by touch) of both solenoid valves (fuel supply and fuel return). No audible "click" or action indicates solenoid valve(s) is defective. Fuel flow indicates solenoid valve is operating properly and fuel filters are satisfactory. With switch in "ON" position, note fuel flow from tee opening with each purge pump stroke. No fuel or restricted flow indicates manifold heater filter or felt filters in solenoid valve are restricted or clogged. If fuel flow stops, solenoid valve is closing properly. To Check Solenoid Valve and Fuel Filter: Disconnect one fuel tube from engine front solenoid valve outlet tee, operate purge pump and press heater switch "ON" and "OFF". With switch in "OFF" position note that fuel flow stops. If fuel flow continues, solenoid valve is defective (stuck open). PROCEDURE OBSERVATION ANALYSIS Moderate flow indicates solenoid valve is operating properly and check valve is opening properly. With switch in "ON" position, note fuel flow from check valve opening. No fuel or restricted flow indicates check valve stuck closed or felt filters in solenoid valve are restricted or clogged. If fuel flow stops, solenoid valve is closing properly. To Check Return Fuel Solenoid Valve and Check Valve: Remove fuel return solenoid outlet tube after the check valve at rear of engine, operate purge pump and press heater switch "ON" and "OFF". With switch in "OFF" position note that fuel flow stops. If fuel flow continues, solenoid valve is defective (stuck in open position). PROBABLE CAUSE CORRECTIVE ACTION a. (Continued) Manifold heater solenoid valves defective. (2) Replace solenoid valve (WP 0087, Manifold Heater Fuel Filter and Solenoid Replacement). WP 0015 00-3