Governor General The engine is equipped with a centrifugal flyweight mechanical governor. It is designed to hold the engine speed constant under changing load conditions. The governor gear/flyweight mechanism is mounted inside the crankcase on the oil pan, and is driven off the gear on the camshaft. The governor works as follows: Centrifugal force acting on the rotating governor gear assembly causes the flyweights to move outward as speed increases. Governor spring tension moves them inward as speed decreases. As the flyweights move outward, they cause the regulating pin to move outward. The regulating pin contacts the tab on the cross shaft causing the shaft to rotate. One end of the cross shaft protrudes through the crankcase. The rotating action of the cross shaft is transmitted to the throttle lever of the carburetor through the external linkage. See Figure 5-66. When the engine is at rest, and the throttle is in the fast position, the tension of the governor spring holds the throttle plate open. When the engine is operating, the governor gear assembly is rotating. The force applied by the regulating pin against the cross shaft tends to close the throttle plate. The governor spring tension and the force applied by the regulating pin balance each other during operation, to maintain engine speed. When load is applied and the engine speed and governor gear speed decreases, the governor spring tension moves the governor lever to open the throttle plate wider. This allows more fuel into the engine, increasing engine speed. As speed reaches the governed setting, the governor spring tension and the force applied by the regulating pin will again offset each other to hold a steady engine speed. Adjustments General The governed speed setting is determined by the position of the throttle control. It can be variable or constant, depending on the engine application. Hex Nut Governor Arm Cross Shaft Governor Figure 5-66. Governor s and Linkage (External). Initial Adjustment NOTE: EFI engines require a special initial adjustment procedure, which is covered in subsection 5B. Refer to Initial Governor Adjustment in that section for setting the governor on EFI-equipped engines. Procedure - Carburetor Equipped Engines Make this adjustment whenever the governor arm is loosened or removed from the cross shaft. See Figure 5-66 and adjust as follows: 1. Make sure the throttle linkage is connected to the governor lever and the throttle lever on the carburetor. 2. Loosen the hex nut holding the governor lever to the cross shaft. 3. Move the governor lever toward the carburetor as far as it will move (wide-open throttle) and hold in position. 4. Insert a nail into the hole in the end of the cross shaft and rotate the shaft counterclockwise as far as it will turn, then tighten the hex nut securely. 5.30
Sensitivity Adjustment Governor sensitivity is adjusted by repositioning the governor spring in the holes of the governor lever. If speed surging occurs with a change in engine load, the governor is set too sensitive. If a big drop in speed occurs when normal load is applied, the governor should be set for greater sensitivity. See Figure 5-66 and adjust as follows: 1. To increase the sensitivity, move the spring closer to the governor lever pivot point. 1. With the engine running, move the throttle control to fast. Use a tachometer to check the RPM speed. 2. Loosen the lock nut on the high speed adjusting screw. Turn the screw counterclockwise to decrease, or clockwise to increase RPM speed. Check RPM with a tachometer. 3. When the desired RPM speed is obtained, retighten the lock nut. 2. To decrease the sensitivity, move the spring away from the governor lever pivot point. High Speed (RPM) Adjustment (Refer to Figures 5-67, 5-68, or 5-69.) NOTE: When the throttle and choke control cables are routed side-by-side, especially under a single clamp, there must be a small gap between the cables to prevent internal binding. After the high-speed setting has been completed, check that there is a gap of at least 0.5 mm (0.020 in.) between the control cables. 5 Left Side Pull Lever #2 Choke Kill Switch Choke Lever #1 Choke Linkage Z Bend Kill Switch Adjusting Screw Dual High Speed Lever Stop Screw "Do Not Remove" High Speed Adjusting Screw Figure 5-67. Governor Connections. High Speed Lever Choke Right Side Pull 5.31
Choke Lever Detail Choke Lever Screw Bracket Blower Housing Choke Fastener Choke Lever (See Detail at Left) Screw and Nut Lever Fastener Lock Nut Linkage Fuel Pump Clip Lever Fuel Line Linkage Shaft Bracket Locker Nut Lever Deflector (If So Equipped) (Place Between Valley Baffle and Shaft Bracket) Figure 5-68. Governor Used with Commercial Mower Air Cleaner (CV17-745). Commercial Mower Governor Arrangement The Commercial Mower governor arrangement shown in Figure 5-68 is used primarily on wide area walk behind mower applications. The initial adjustment and sensitivity adjustment is the same as for the standard governor. The governor and controls for the CV750 engine is shown in Figure 5-69. Should the governor spring be disconnected from the throttle lever and governor lever, reconnect it as follows: 1. Hook the long end of the spring through the hole in the lever from the left side. 2. Rotate the spring 180 until hooked as shown in Figure 5-69. 3. Hook the short end of the spring into the appropriate hole in the governor lever. Refer to the appropriate chart in Section 11 - "Reassembly" of this manual for the correct hole to use for the speed involved. 5.32
Screw Choke Linkage Choke and Screw Hex Nut Screw Lever 5 Bracket Screw Linkage Fuel Pump Linkage Governor Lever Fuel Shaft Shaft Bracket Figure 5-69. Governor/s Assembly (CV750). Governor Lever Deflector (If So Equipped) 5.33
B EFI Fuel System Section 5B Electronic Fuel Injection (EFI) Fuel System Contents Page(s) Description Initial Starting/Priming Procedure...5B.2 Fuel Recommendations... 5B.2-5B.3 EFI Fuel System Components...5B.3 Operation...5B.3 Important Service Notes...5B.4 Electrical Components Electronic Unit (ECU)... 5B.4-5B.5 Engine Speed Sensor... 5B.5-5B.6 Position Sensor (TPS) and Initialization Procedures... 5B.6-5B.9 Engine (Oil) Temperature Sensor... 5B.9-5B.10 Oxygen Sensor... 5B.10-5B.12 Electrical Relay... 5B.12-5B.13 Fuel Injectors... 5B.13-5B.16 Ignition System...5B.17 Spark Plugs...5B.18 Wiring Harness...5B.18 Battery Charging System...5B.18 5B Fuel Components Fuel Pump... 5B.18-5B.19 Fuel Pressure Regulator... 5B.19-5B.21 Fuel Filter...5B.21 Fuel Rail...5B.21 Fuel Line... 5B.21-5B.22 Body/Intake Manifold Assembly...5B.22 Idle Speed Adjustment (RPM)... 5B.22-5B.23 Initial Governor Adjustment... 5B.23-5B.25 Troubleshooting Troubleshooting Guide...5B.25 Electrical System... 5B.25-5B.29 Fuel System...5B.30 Fault Codes... 5B.30-5B.38 Troubleshooting Flow Chart... 5B.38-5B.39 Flow Chart Diagnostic Aids... 5B.40-5B.41 EFI Service Tools... Refer to Section 2 5B.1
B EFI Fuel System Description 2. For plastic-cased ECU s below 24 584 28-S, the system can be primed by manually cycling the fuel pump. WARNING Explosive Fuel can cause fires and severe burns. a. Turn the key switch to the on/run position. The fuel pump will run for about three seconds and stop. Turn the switch off and back on to restart the fuel pump. Repeat this procedure until the fuel pump has cycled five times, then start the engine. Fuel system ALWAYS remains under HIGH PRESSURE. WARNING: Explosive Fuel! Gasoline is extremely flammable and its vapors can explode if ignited. Store gasoline only in approved containers, in well ventilated, unoccupied buildings, away from sparks or flames. Do not fill the fuel tank while the engine is hot or running, since spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Do not start the engine near spilled fuel. Never use gasoline as a cleaning agent. The EFI fuel system remains under high pressure even when the engine is stopped. Before attempting to service any part of the fuel system, the pressure must be relieved. Pressure tester, (part of EFI Service Kit, see Section 2) has an integral relief valve. Connect the black tester hose to the test valve in the fuel rail. Route the clear hose into a portable gasoline container. Depress the button on the tester relief valve. Initial Starting/Priming Procedure Important: The EFI fuel system must be purged of air (primed) prior to the initial start up, and/or any time the system has been disassembled or the fuel tank run dry. 1. Locate the electronic control unit (ECU) for the EFI system. Check the part number on the end. If the Part No. is 24 584 28 or higher, the ECU has a built-in priming feature. a. Turn the key switch to the on/run position. You will hear the fuel pump cycle on and off. When the fuel pump stops cycling (approximately one minute), the system is primed; start the engine. 3. The system can also be primed similar to relieving pressure. a. Connect the pressure gauge as described above for relieving fuel pressure. Depress and hold the release button and crank the engine until the air is purged and fuel is visible in the discharge tube. If fuel is not visible after 10 seconds, stop cranking and allow the starter to cool for 60 seconds. Fuel Recommendations General Recommendations Purchase gasoline in small quantities and store in clean, approved containers. An approved container with a capacity of 2 gallons or less with a pouring spout is recommended. Such a container is easier to handle and helps prevent spillage during refueling. Do not use gasoline left over from the previous season, to minimize gum deposits in your fuel system, and to ensure easy starting. Do not add oil to the gasoline. Do not overfill the fuel tank. Leave room for the fuel to expand. Fuel Type Do not use leaded gasoline, as component damage will result. Any costs/damages incurred as a result of using leaded fuel will not be warranted. Use only clean, fresh, unleaded gasoline with a pump sticker octane rating of 87 or higher. In countries using the Research method, it should be 90 octane minimum. 5B.2