Many of the troubles that can lead to loss of power in an engine may also cause the engine to stop and stall suddenly or may even prevent it from starting. Compare the list of some of the troubles that may cause a power loss (fig. 3-41) with those in figures 3-36 and 3-40. Such items as insufficient air, insufficient fuel, and faulty operation of the governor appear on all three charts. Many of the troubles listed are closely related, and the elimination of one may eliminate others.

The operator of an internal-combustion engine may be confronted with additional major difficulties, such as those indicated in figure 3-42. Here, again, you can see that many of these possible troubles are similar to those that have already been discussed in connection with starting failures and with engine stalling and stopping. The discussion that follows covers only those troubles not previously considered.

ENGINE OVERSPEEDS

When an engine overspeeds, the trouble is usually caused by either the governor mechanism or the fuel control linkage, as previously discussed When you need information on a specific fuel system or speed control system, check the manufacturers technical manual and the special technical manuals for the particular system. These special manuals are available for the most widely used models of hydraulic governors and overspeed trips, and they contain specific details on testing, adjusting, and repairing each controlling device.