COVER 4L1268 - Caterpillar

Misfiring And Running Rough
See MISFIRING AND RUNNING ROUGH.Problem With Vehicle Or Vehicle Operation
See PROBLEM WITH VEHICLE OR VEHICLE OPERATION.Low Engine RPM
Governor Linkage...Disconnect the governor linkage at the lever on the governor. Move the governor lever by hand until the linkage inside the governor is against the high idle stop. With the accelerator pedal all the way down, adjust the linkage so the inside linkage is against the high idle stop. Some trucks are equipped with linkage which has spring force and some are equipped with a governor lever of the break over type. On engines with either of these, adjust the governor linkage .250 in. (6,35 mm) longer than necessary for the inside linkage to be against the high idle stop, this will keep tension on the spring at all times. For trucks with tilt cabs, do not make this check with the cab tilted.Governor High Idle Adjustment...If the governor linkage moves the governor lever to the fully open position, check the high idle rpm with a good tachometer. *Not Enough Air
Inlet Restriction...An inlet restriction will cause low power and too much smoke when under load. Check for a restriction with a water manometer or a vacuum gauge (which measures in inches of water). Connect the gauge to the engine air inlet between the air cleaner and the engine. With gauge installed, run engine at high idle rpm and check the restriction. Maximum restriction of the air inlet is 25 inches (635 mm) of water. If the indication is higher than the maximum permissible restriction, clean or install a new filter element and check the restriction again. If the indication is still too high, there must be a restriction in the inlet piping.Exhaust Restriction...Make a visual inspection of the exhaust system and look for damage to piping or muffler. If no damage is found, you can also check the system by removing the exhaust pipes from the exhaust manifolds. With the exhaust pipes removed, start and run the engine to see if the problem is corrected.Exhaust restriction can be checked with a manometer.Low Quality Fuel
Water in Fuel...Drain a small amount of fuel from the tank and check for water in the fuel. If there is water in the fuel, drain tank. Install a new fuel filter and fill the fuel tank with clean fuel. "Prime" (remove the air and/or low quality fuel from the fuel system) the fuel system. See PRIMING FUEL SYSTEM.Fuel With Low Specific Gravity...Remove a small amount of fuel from the tank and measure the API gravity with a fuel hydrometer. Caterpillar engines are rated on fuel having 35 API gravity at 60°F (16°C). If the API gravity of the fuel used is more than 40, the result will be a reduction in power.Fuel System Problems
Low Fuel Pressure...Remove the cap from the tee at the fuel filter. Connect a pressure gauge to the tee. Run the engine under load and check the pressure. If the pressure is lower than 13 psi (0,9 kg/cm2), install a