How to rule out the possible causes of Caterpillar 320c engine misfire or engine running unstable

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                                                          Engine Left View

 1-Fan  2-Water outlet  3-Turbocharger  4-Exhaust manifold  5-Exhaust outlet  6-Crankshaft pulley  7-Oil pan  8- Flywheel housing Figure 

                                                     engine right view

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(1) The fuel pressure is low. Make sure there is enough fuel in the fuel tank. Check the fuel system for leaks. Check the fuel line between the fuel tank and the fuel transfer pump for severe bends. Check for air in the fuel system. Check fuel pressure. At full load speed, the output pressure of the fuel delivery pump is (240±35) kPa. If the fuel pressure drops, install a new fuel filter element. Check that the fuel bypass valve moves freely and install a new fuel bypass valve if necessary. 

 (2) There is air in the fuel system. Find the leak in the fuel system and fix the leak. Remove air from the fuel system. 

 (3) The fuel pipeline between the fuel injection pump and the fuel injection valve leaks or ruptures. Install new fuel lines. 

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 (4) The valve clearance is incorrect. Adjust the valve clearance. 

 (5) The fuel injector is faulty. Run the engine at a specific speed to maximize misfiring or rough running. Then, loosen the fuel line nuts of the fuel injectors of each cylinder one by one. Every time a fuel line nut is loosened, misfire or rough running will be exacerbated. If the above situation does not occur after loosening a certain fuel line nut, the fuel injector of that cylinder should be tested. Install new parts if necessary. 

 (6) Fuel injection timing error. Adjust fuel injection timing. 

 (7) The push rod is bent or broken. Replace push rod. (8) The valve seat or valve surface is worn. The cylinder head needs to be repaired.

(8) The valve seat or valve surface is worn. The cylinder head needs to be repaired.