SWEEP GP 3727834 - Caterpillar

Recommendations To Reduce Smoke Levels
If excessive black smoke has been reported, first determine the operating conditions under which this occurs. Generally these conditions can be characterized as one of the following: - Only during acceleration- During both acceleration and steady load- Coming from only one bank of the engine
Smoke only during acceleration indicates a maladjusted or malfunction of the governor fuel ratio control. Smoke during both acceleration and steady load can be attributed to a number of reasons which will be discussed later. Smoke coming from only one bank of the engine indicates a problem isolated to one or more cylinders of the engine.
Smoke Occurs Only During Acceleration
Typically if heavy black smoke occurs only during acceleration, check for a problem with the fuel ratio control or check the limit setting.
The governor fuel ratio control (FRC) is designed to restrict the amount of fuel injected during the time that it takes the turbocharger to come up to speed and provide positive boost pressure in the inlet manifold. The FRC is adjusted to a limit setting which provides the best compromise between exhaust smoke and engine response. A low FRC setting will reduce smoke during acceleration, but will inhibit engine response time. Conversely, a high FRC limit setting will increase the smoke during acceleration, but will improve engine response time. As the turbocharger boost comes up, the fuel ratio control moves out of the way of the governor/fuel system linkage. Under most operating conditions other than acceleration from a stop, the FRC does not have an affect on the governor and does not effect the smoke level.
Earlier 3161 Governors used a fuel ratio control which required both oil pressure and boost pressure to arm the fuel ratio control. A leak in the diaphragm would not allow the fuel ratio control to arm and limit the fuel injected during acceleration. This would result in very heavy black smoke. The 2W4531, 7W4963, 7C3791, 7C4271 and 7C9456 3161 Governors were equipped with this style of fuel ratio control.
Later 3161 Governors use an FRC which is always armed. A leak in the FRC diaphragm will not allow the control to react to boost pressure and always limits the fuel to the adjusted limit setting. Instead of heavy black smoke, the engine would exhibit low power assuming the limit setting is correct. If the limit setting is high, then heavy black smoke would be seen. The 9Y2133, 9Y6680, 9Y7559, and 7E7249 3161 Governors are equipped with continually-armed FRC's.
Earlier 3161 Governors contained a limiter mechanism that would wear and allow growth of the limiter setting. The new governor has a new smoke limiter that will eliminate internal wear. Also, the limit setting of the smoke limiter has been reduced from 2.00 mm (.079 in) to 1.00 mm (.039 in). In addition, a stiffer spring is used against the diaphragm. The stiffer spring will cause the FRC to react slower and reduce the transient smoke during acceleration. The 7E7249 Governor contains the improved FRC limiter mechanism, lower