SERVICE MANUALROBERT BOSCH MODEL MW INJECTION PUMPSection 11When the control lever contacts the low idle stop, theinjection pump is in the low idle speed position. Low idlespeed is changed by moving the low idle adjustmentscrew and should be adjusted with the engine atoperating temperature. To compensate for parasiticloads which affect low idle speed, the low idle speedshould be set slightly higher so engine speed will bewithin specifications when load is applied. Examples ofmajor parasitic loads are mixer drums and automatictransmissions.RQV GOVERNOR AND ANEROID (Figure 17)Low idle speed can be adjusted on the engine asdescribed in the on-engine repairs section. If diagnostictesting confirms that any other adjustment is indicated,follow the current warranty procedures to resolve theproblem.To replace a leaking aneroid diaphragm, the injectionpump must be removed, the new diaphragm installedand the injection pump recalibrated. DO NOT ATTEMPTTO REPLACE THE ANEROID WITHOUT RE-CALIBRATING THE INJECTION PUMP. SEEMINGLYSMALL CHANGES TO THE INJECTION PUMPCONTROL RACK SETTINGS CAN DESTROY THEENGINE.Figure 17. - RQV Governor and AneroidON-ENGINE INJECTION PUMP REPAIRSREMOVALCLEANLINESS IS OF UTMOST IMPORTANCE WHENSERVICING FUEL INJECTION SYSTEMS. ALWAYSCLEAN ENGINE BEFORE INJECTION PUMP ISREMOVED OR DISCONNECTING FUEL LINES.ALWAYS PLUG OR CAP ANY OPENING TOPREVENT DIRT, PAINT CHIPS OR OTHER FOREIGNMATERIAL FROM ENTERING THE FUEL SYSTEM.Barrel to plunger clearances are approximately onehundred millionths of an inch (0.0001000 inches).Normally the difference between a serviceable and aworn out barrel and plunger assembly is that dirt enteredthe fuel system and caused minute wear between thebarrel and plunger.Thorough cleaning prior to disassembly and anunderstanding that any dirt entering the injection pumpcauses damage is essential to obtaining long fuel systemlife.NOTE: Prior to injection pump removal, conduct thediagnostic checks and adjustments found in theappropriate diagnostic manual.CGES-185-3PRINTED IN UNITED STATES OF AMERICAPage 14
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