A fuel pump relay takes control of the fuel pump during engine startup, but shuts itself off after the engine is running. An oil pressure mechanism resumes control of the fuel pump after the fuel pump relay shuts off and the vehicle's engine is running. The oil pressure mechanism also relays oil pressure data to the gauges on the inside of the driver's dashboard. The vehicle will not start, however, if there isn't enough oil pressure to generate the electricity needed to run the fuel pump. When the oil is warm, it becomes thinner, making it difficult to pump into the engine. The fuel pump relay generates a humming sound when the ignition is turned on. When the humming sound is not audible, it is time to have the fuel pump relay replaced by a mechanic. The starter cranks are charged up by a cold start valve, which is operated by the thermo timing switch. This valve injects fuel when heat is at a minimal level. While cold start valve is operating, the thermo timing switch heats up (while cranking). The cold start valve will stop injecting fuel if the engine fails to start after prolonged attempts to start the engine (this is done to avoid flooding the engine with fuel).