Symptom:
A Mercedes-Benz 560 car, driving about 150,000 km, the engine suddenly turned off after the start can not be.
Troubleshooting:
¢Ù with the starter to drive the engine, without any signs of starting.
¢Ú check the normal high pressure fire.
¢Û check the nozzle with a stethoscope, you can hear the sound of fuel injection.
¢Ü from the exhaust pipe can smell the thick smell of gasoline.
¢Ý demolition of the spark plug has been significantly flooded the characteristics.
Failure analysis:
Through the inspection of the fault, you can initially conclude that the combustible mixture is caused by over-concentration. For the mechanical fuel injection engine, what is the reason for the mixture in the start when the mixture is too thick?
Mechanical fuel injection device in the engine cold start conditions when the fuel supply is composed of two parts: one is the idle fuel supply; the second is the cold start enrichment fuel supply. Cold start enrichment The oil supply is done by means of a cold start injector and controlled by a temperature-time switch (temperature-time switch structure shown in Figure 1). When the temperature of a switch failure, will cause the mixture is too thick. Usually a temperature-time switch to extend the fuel supply time, but will not appear in the start when there is no sign of the phenomenon of starting. The rest is the increase in idle fuel supply caused by the mixture is too thick. Mechanical fuel injection device Idle fuel supply by the mixture regulator (also known as the mixture distributor) in the control of the position of the plunger. Control the initial position of the plunger rise, the idle fuel supply increases. So should focus on checking the initial position of the control plunger.
Troubleshooting:
Pull the airflow sensation board up and down by hand, should feel free travel, generally should be about 1mm (shown in Figure 2). The car's air flow sensing plate free travel up to 10mm or more, indicating that the control plunger has been stuck in the fuel supply position, resulting in increased fuel supply idling, mixed gas is too thick and can not start.
Remove the mixing regulator and remove the control plunger, rinse the control plunger and plunger with a clean petrol, and keep it clean, replace the test, and troubleshoot it.
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