pressure on the fuel within the pumping chamber. Residual pressure in the fuel lines closes the reverse flow check valve in the pump and prevents surges on the fuel lines. No fuel flowing permits the injection valve to close and complete injection.
The camshaft continues to lift the plunger to the top of the stroke. The fuel in the housing fills the space in the pumping chamber through the fuel outlet until the sleeve closes the outlet on the downward stroke. Spring pressure pushes the plunger farther down as the
Figure 5-15.-Sleeve metering fuel pump.
camshaft rotates, allowing the fuel inlet to fill the rest of the chamber and restarting the cycle.
GOVERNOR. - The mechanical type governor shaft of the governor for the sleeve metering fuel system controls the position of the sleeve on the plunger, which regulates the amount of fuel injected. The volume of fuel injected is equal to the displacement of the plunger lift into the barrel between the start and end of injection. The start-up control sets the fuel injection pumps at full stroke to aid in starting, regardless of the throttle position. Normal governor operation takes over at low-idle speed, approximately 500 rpm.
TROUBLESHOOTING AND ADJUSTMENTS. - Most problems in this system can be traced to lack of fuel, low fuel pressure, dirty fuel filters, poor quality fuel, or a broken or damaged fuel line. Air enters the fuel system when there are loose connections of the suction side of the pump.
Individual fuel injection pumps for each cylinder with built-in calibration means little or no balancing or adjustment. Before you calibrate any sleeve metering fuel system, be sure the proper tools and manuals are available.
The Construction Mechanic 3 & 2 covers the general construction and operation of the Roosa Master DB and DC fuel injection pumps.
In this TRAM AN, you will learn about troubleshooting, disassembly, inspection, reassembly, and testing of the basic DC fuel pump of the Roosa Master system. Before you perform any work on an injection pump, refer to the manufacturer's maintenance and service manuals.
The troubleshooting chart (table 5-1 ) lists some of the problems and their possible causes that you might encounter in the Roosa Master fuel system.
A field test (Kiene) on an engine is an efficient way to pinpoint the cause of poor engine performance. This test will eliminate unnecessary fuel injection pump removal. Since this field test permits some analysis of engine condition, as well as the fuel system, you will quickly see the extent of the difficulty and the required remedies.Continue Reading