The remote run/stop control for the engine is accomplished through the use of a special high pressure valve. When the valve is energized with +12 volts from the control panel, it closes and the injection pump is allowed to deliver high pressure fuel to the injector. If the valve is de-energized (no +12 volt supply), the high pressure fuel is “dumped” into the return line and the injector will not receive fuel.
The engine control system has been designed to not only start and stop the engine, but also to provide safety shut downs. Low oil pressure, high coolant temperature, and/or high exhaust elbow temperature will cause the engine to stop. There are three switches on the engine to monitor these functions.
The oil pressure switch is mounted on the left side of the engine, looking at the hand crank end (see Parts page 2, item 5). It is normally open and is set to close when the oil pressure rises to 15 psi. If the pressure falls below 15 psi, it will re-open.
The water temperature switch is located on the cylinder head (see Parts page 8, item 47)
. It is normally closed and will open when the engine coolant temperature rises to 185 degrees F. It will close again at approximately 160 degrees F.
The exhaust temperature switch is located in the casting of the exhaust elbow (see Parts page 16, item 19)
. It is normally closed and will open when the internal temperature of the elbow rises to 185 degrees F. It will close again at approximately 160 degrees F.
Theory of Operation
Please refer to the Control System Schematic.
+12 Battery Cable.
The +12 volt battery should be connected to the large terminal on the starter motor solenoid.
-12 Battery Cable.
The -12 volt battery cable terminal should be connected to the crankcase of the engine at any convenient point. Preferably at one of the starter mounting bolts, (this is control system ground).
Plus 12 volts is taken from the starter post and thru the wiring harness, it is applied to two terminals of the start/stop switch, located on the remote control panel.
When the start/stop switch is moved to the run position, +12 volts is applied back through the harness to one side of the water temperature switch. The water temperature would normally be below 185 F., so the switch would be closed. The +12 volts will pass through the switch to one side of the exhaust temperature switch, and also to the water lamp on the control panel causing it to illuminate.
Exhaust Temperature Switch.
The exhaust temperature switch would normally be below 185 F., so it would also be closed. The voltage would pass through the switch and go to one side of the oil pressure switch. It would also go to the exhaust lamp, on the control panel causing it to illuminate.
Oil Pressure Switch.
The oil pressure switch is still open, because there is no oil pressure, and therefore the voltage will be blocked. The oil lamp will not light, the hour meter will not count, and the fuel control valve will not energize.
Starting the Engine.
Moving the start/stop switch to the start position feeds +12 volts to the start relay (located near the start motor) causing it to energize. The heavy internal contacts of the start relay close, and +12 volts is applied to the start solenoid on the start motor. The start motor cranks the engine, and two things happen simultaneously: the oil pump in the engine starts to pump oil into the galley; and oil flows to the bearings, lubricating them. The oil pressure rises from zero to operating pressure. When the pressure reaches 15 psi, the oil pressure switch closes and the +12 volts passes through the switch to the fuel control valve energizing it, and to the oil light causing it to illuminate.
As soon as the fuel control valve is energized, high pressure fuel will be delivered to the injector pipe and thus to the injector. If the engine is operating normally, it will start within 3 to 7 seconds. The control panel will show a "green board" (all lights green), and the engine will be running.
If the engine has been properly maintained, and all of the external support systems, including raw water feed, fuel feed, battery power, etc., are functioning properly, the engine will normally start within 3 to 7 seconds. If the engine does not start within this time period, try only one more cranking attempt. DO NOT CONTINUE CRANKING ! ! !
Low Oil Pressure.
If the oil pressure drops below the 15 psi level, the oil pressure switch will open, the OIL light will go out and the fuel control valve will de-energize causing the engine to stop.
High Exhaust Temperature:
If the sea water flow is not sufficient, the exhaust manifold will get hot and the exhaust switch will open. Both the EXHAUST light and the OIL light will go out, and the engine will stop.
High Cylinder Head Temperature:
If the cylinder head temperature rises to the 185 degree F. point, the water temperature switch will open. ALL of the lights will go out and the engine will stop.
If battery power is turned off, the engine will stop!
If for any reason, the control system will not stop engine, it can be stopped by rotating the external lever on the side of the engine, behind the water pumps, to the full clockwise position. After the engine stops, return the control to the full counterclockwise position.