Engine Start-Up; Figure 5-2. Start Fuel Limit - Woodward 723PLUS Technical Manual

723PLUS Digital Marine Control
The 723PLUS control pre-calibration is now complete and the engine is ready to
be started. The first attempt to start the engine should be done with the fuel shut
off to prevent the engine from starting. This will allow the 723PLUS control,
actuator, and actuator wiring to be checked prior to actually running the engine.
Begin by measuring the dc voltage at terminal 19 & 20. With the engine stopped,
the voltage should be 7.0 Vdc (reverse acting). Begin cranking the engine and
verify the voltage on terminals 19 & 20 decreases for reverse acting, to
approximately 3.50 Vdc (assuming 50% start fuel limit). The voltage will vary
depending on actuators as well as the start fuel limit setting. The voltage will be
proportional to the start fuel limit. While the engine is cranking, verify the actuator
movement on the engine is in the increase-fuel direction. This test can be done
at the same time the speed sensors are being tested.
While the engine is cranking, the speed sensors can also be tested. To test the
MPUs, crank the engine without starting the engine. Verify the fuel is shut off to
prevent the engine from running. The value viewed in Service mode under
header A**DISPLAY 1** at the prompts 10 ENGINE SPEED MPU#1 and 11
ENGINE SPEED MPU#2 should increase to the engine cranking rpm. To check
speed sensor #1 input signal strength, measure the RMS voltage at terminals
11–12 and 13–14. The voltage must be 1.0 Vrms or greater during cranking.
Prepare the engine for a normal start (restore all shut off fuel, start air, etc.). Be
prepared to shut down the engine should a problem arise during the start. Verify
the proper engine overspeed devices function.
Be prepared to make an emergency shutdown when starting the
engine, turbine, or other type of prime mover, to protect against
runaway or overspeed with possible personal injury, loss of life, or
property damage.
74

Figure 5-2. Start Fuel Limit

Engine Start-up

Manual 26482
Woodward