TM-9-2320-280-20 HMMWV Technical Manual Unit Maintenance Volume 1 Download
Page 186 of 890
TM 9-2320-280-20-1 REFERENCE INFORMATION Watch the fuel pump pressure while slowly accelerating the angina from idle to maximum speed. The pressure should always be greater than zero. If pressure, check to be sure it is still above zero even during maximum acceleration (maximum engine power). You can use STE/ICE test 24 with control function 02 (minimum). NOTE Rapidly accelerating the engine with the transmission in neutral doesn't work for this engine because the fuel supply can’t increase as fast as the engine can accelerate so you won’t get good test results. Proper engine performance is dependent upon the availability of the correct fuel volume to the injection pump. Pay attention to when the engine runs rough. If it runs rough only while warming up after a cold start it may be a glowplug problem and you should run the Glowplug Circuit tests. Rough running may also be caused by air leaks in the fuel supply lines. Air in the fuel should purge itself while idling. If rough running occurs after a period of high speed or high power running but seems to go away after idling, then look for air leaks in the fuel supply lines and fittings. if rough running occurs while driving but idles ok, check the fuel return check valve for any malfunctions (refer to para. 3-35). NOTE Try to adjust the engine idle speed by turning the idle speed screw (refer to para 3-44). Continue testing if you can adjust the speed properly. If you cannot, notify DS maintenance. Engine must be at normal operating temperature when making speed checks. Air fitter must be in place and all accessories (lights, heater fan, etc...) must be turned off. This engine has a min-max governor which controls engine speed at both idle and full throttle. FUEL SYSTEM 2-99