How to check air in fuel and engine speed 

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 A. Check the air in the fuel The air in fuel test procedure is used to check the air in the fuel. This procedure can also help find the source of the air.  

(1) Check the fuel system for leaks. Make sure the fuel line connector is tightened well. Check the fuel level in the fuel tank. Air can enter the fuel system from the suction side between the fuel transfer pump and the fuel tank. 

 (2) Install a 2P-8278 fuel flow pipe (observation instrument) in the fuel return pipe. If possible, install sight gauges in a straight section of fuel line that is at least 304.8mm long. NOTE: Do not install scopes in right -angle elbows, safety valves, and check valves. As shown in Figure 3-1-41, observe the fuel flow when the engine is started. Look for air bubbles in the fuel. If there is no oil in the sight gauge, refill the fuel system. If the engine starts, check the air in the fuel at various engine speeds. If possible, run the engine with the assumption that there is air in the fuel. 

 (3) If too many bubbles are seen in the sight gauge, install a second sight gauge at the inlet of the fuel transfer pump. If a second sight gauge is not available, remove the sight gauge from the fuel return pipe and install it at the inlet of the fuel transfer pump. Observe fuel flow when the engine is started. Look for air bubbles in the fuel. If the engine is started, check the air in the fuel at various engine speeds. If at the inlet of the fuel transfer pump If excess air is not seen, the air will be sucked into the system after passing through the fuel transfer pump, proceed to step (6); if too much air is seen at the inlet of the fuel transfer pump, the air will enter through the suction side of the fuel system In the oil transfer pump. NOTE: To avoid personal injury, always wear a protective mask when working with compressed air. To avoid tank damage, do not pressurize the fuel tank beyond 55kPa.  

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(4) Pressurize the fuel tank to 35kPa. To avoid damage to the fuel tank, do not apply more than 55kPa pressure to the fuel tank. Check the fuel line between the fuel tank and fuel transfer pump for leaks. If there is an oil leak, repair it. Check the fuel pressure and make sure the fuel transfer pump is working properly. 

 (5) If the source of air is not found, disconnect the fuel tank supply line and connect the external fuel supply to the inlet of the fuel transfer pump. If this solves the problem, repair the fuel tank or the standpipe in the fuel tank . 

 (6) If the injector sleeve is damaged or damaged, combustion gases will leak into the fuel system. If the O-ring on the injector sleeve is broken, missing, or damaged, combustion gases can also leak into the fuel system. 

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 B. Check the engine speed

  The tool required to check the engine speed is 1U-6602 optical tachometer (This unit is a portable service tool) or the 9U-7400 Multi-Stage Tachometer Tool Assembly (Figure 3-1 -42). NOTE: It is also possible to use the electronic service tool and see the engine rpm on the status screen of the electronic service tool. The 9U-7400 multi-stage tachometer tool assembly measures engine speed using an electromagnetic pickup sensor. The electromagnetic pickup sensor is located in the flywheel housing. Multi-level tachometers can also measure engine speed by visual inspection of rotating engine parts. 1U-6602 optical tachometer is a universal optical speedometer. The 1U-6602 optical tachometer records only the fundamental input frequency of any visually rotating part. The fundamental input frequency is the pulse generated per revolution of each reflective strip.