BONNET 3493311 - Caterpillar

3400 Series Engines ( 90U, 91U, 92U, 67U, 99U, 28V, 38S, 60M ),
D346 ( 39J, 40J, 98N ),
D348 ( 36J, 38J, 57K ),
D349 ( 61P, 62P, 32R)Introduction
This instruction outlines the procedure to troubleshoot response and low power problems.Response is the engine's ability to accelerate, under load, to its rated horsepower. Poor response can result from problems with the governor, the fuel ratio control or the shutoff system.Low power is the engine's inability to produce its rated horsepower. Low power can result from problems with the fuel pump, the governor setting, the shutoff system or the other fuel flow components, or with the engine application.A new procedure for confirming and isolating response problems has been developed.The new procedure will test the response functions of the governor, the fuel ratio control and the shutoff system. It will verify whether or not the response functions are within specifications. If they are not within specifications, the procedure will isolate the cause of the problem.This new procedure also will check governor settings, fuel ratio control settings, full load measurements and governor servo measurements. These checks are completed without disassembly of the governor or the fuel ratio control, thereby eliminating the need to break the governor seal if no readjustment is required.A dealer-fabricated tester (drawing FT1906) is needed for this procedure. This tool will check the governor, the fuel ratio control and servo. It will permit testing with or without a dynamometer. The FRC tests can be obtained below full load rpm, but full load is necessary for a complete engine system check.The following chart lists all the components of the FT1906 Fabricated Tester. All components, except for the tubing and the bulb, are available from Caterpillar Inc. The tubing and the bulb can be purchased at a medical supply store. Figures 1 and 2 show how to assemble the tester.
FIGURE 1 Fabricated Tester
FIGURE 2 Fabricated TesterTroubleshooting Procedure for Engine Response, Fuel Ratio Control Governor
Connect the fabricated tester to the fuel control and to the inlet manifold. Figure 2 shows the proper connections. Install the 6V4060 Engine Set Point Indicator Group or a continuity light. A commercially available circuit testing flashlight is recommended.Remember, two points during the procedure. For constant repeatable readings under load, the engine must be at full throttle. If full fuel position is not used, incorrect readings or no readings will result. Most fuel ratio controls allow full fuel position at or above 381 mm (15") Mercury (Hg) or 52 kPa (7.5 psi) for Current Scroll Fuel System (CSFS). The travel test in Full Fuel Test (No Load Test) will confirm this point. Response or power problems at greater manifold pressures are not usually caused by the fuel ratio control.A chart is supplied in the back of this instruction for recording the tested values. It can be used by itself once you are familiar with the procedure. This chart, SEHS8499-01, is available in pads of 50.Diaphragm Leakage Test (No Load Test)
1. Turn the tester valve so that manual air pressure