TM-9-2320-280-20 HMMWV Technical Manual Unit Maintenance Volume 1 Download
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TM 9-2320-280-20-1 REFERENCE INFORMATION CAUTION Be sure to keep the line clear of moving engine parts (fan, pulleys, etc...) and DO NOT place the line on the exhaust manifold. Fuel lines should be inspected for kinks, cracks, or anything that would restrict fuel flow or allow air into the lines. Be sure to check the lines all the way back to the tank and remember that there is a strainer inside the tank which can also become plugged. To teat for air leaks in the supply lines, disconnect the return line from the injection pump and connect a line that is long enough to reach the ground. Place the end of the line into a bucket containing diesel fuel, making sure that the end of the line is below the level of fuel in the bucket. Run the engine and watch for air bubbles in the bucket. Replace fuel line, refer to (para 3-25). FUEL SYSTEM An important function of all hoses, lines and fittings is to carry fuel without admitting air to the system. When the fuel tank cap is in place and the fuel pump and injection pump are drawing fuel through the lines a low vacuum of 0-1 PSI is created. This occurs because the fuel which the engine uses must be replaced by air. During this vacuum condition, the slightest leak, which may not leak fuel out, could draw air into the system and, depending on the volume of air, cause a wide variety of engine malfunctions. COLD WEATHER OPERATION Diesel fuel is sensitive to temperature. All diesel fuel has a certain amount of wax-like components which have high energy value and help improve fuel economy. When temperatures are less than 20°F (-7°C) these components begin turning into flakes that can build up on the fuel tank strainer or in the fuel filter. FUNGUS In warm or humid weather, fungi and/or bacteria can cause fuel system damage by plugging the fuel lines, filter, or injection nozzles. Old fuel smells like varnish. Check the accelerator pedal for full movement with no sticking or binding. It you have sticking or binding, lubricate accelerator pedal bushing and bearing with seasonal grade OE oil (TM 9-2320-280-10). If you do not have full pedal travel then disconnect the accelerator linkage from the fuel injection pump and recheck the travel. It you now have full travel then the problem is in the fuel injection pump and cannot be handled at this level of maintenance. Operation of the injection pump and injectors cannot be verified at this level of maintenance. 2-121