SHUTOFF AND ALARM SYSTEMSSYSTEMS OPERATIONWATER TEMPERATURE AND OIL PRESSURE SHUTOFF SYSTEM(WITH TIME DELAY RELAY)WIRING DIAGRAM(Fuel Shutoff Solenoid Energized to Shutoff)1. Time delay relay. 2 Oil pressure switch 3. Water temperature switch. 4. Switch (N.O.) 5 Circuit breaker.6. Shutdown relay. 7. Battery. a Diode assembly. 9. Shutoff solenoid. 10 Starter motor.When the engine starts, engine oil pressure will close theN.O. switch and open the N.C. switch in oil pressureswitch (2). This completes the circuit to time delay relay(1). N.O. switch (4) in the time delay relay now closesand completes the circuit between shutdown relay (6)and terminal TD-7 of the time delay relay.If the engine coolant temperature goes above the settingof water temperature switch (3), the N.O. contacts willclose. This lets current flow through water temperatureswitch (3) and through switch (4) to activate shutdownrelay (6) which in turn activates fuel shutoff solenoid (9).When the engine stops, engine oil pressure will becomeless than the setting of the oil pressure switch. The N.O.switch will open and stop the flow of current to the timedelay relay. This will start the time delay relay timer. After70 seconds, switch (4) will open to stop current flowthrough shutdown relay (6). Now, fuel shutoff solenoid(9) will no longer be activated.If engine oil pressure gets less than the setting of the oilpressure switch, the N.C. switch will close. This will letcurrent flow through switch (4) to activate shutdown relay(6) which in turn activates fuel shutoff solenoid (9). TheN.O. switch will open and start the time delay relay timer.After 70 seconds, switch (4) will open to stop current flowthrough shutdown relay (6). Now, fuel shutoff solenoid(9) will no longer be activated.NOTICETo help prevent damage to the engine, find andcorrect the problem that caused the engine toshutdown before the engine is started again.23
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