Throttle persistence

After the engine is started, it runs well from low speed to high speed, but stop immediately after releasing the accelerator pedal. Or unstable operation first, and then shut down. This phenomenon can be judged as idle flameout fault. When the idle speed is turned off, the idle speed should be adjusted according to the actual situation. After adjustment, if the fault disappears, it is improper adjustment of idle screw; If the fault does not disappear after adjustment, open the throttle to keep the engine running, and check the carburetor and intake pipe gasket for air leakage with cotton yarn or paper. If there is no air leakage, the idle metering hole can be removed for inspection, and the idle oil circuit can be blown clean before reassembling and testing; If the fault disappears, the idle metering hole and idle oil passage are blocked. For carburetor with idle stop valve, check whether the circuit of cutting off electromagnetic coil is normal. If the idle fuel-saving metering hole is blocked due to abnormal coil circuit, the cut-off solenoid valve should be repaired.

The engine is unstable when idling, and the exhaust pipe makes a "chug chug" sound, which is generally unstable idling. Keep the engine at a certain speed and listen for air leakage. If it is difficult to find out the location of oil leakage, you can apply a little oil to the middle and lower gaskets of the carburetor. The place where the oil is sucked in is the location of oil leakage, which can be eliminated by fastening screws or adding or subtracting gaskets. Then screw in the throttle adjusting screw to increase the engine speed, then tighten the idle adjusting screw and gradually loosen it to see if the speed is stable; Then loosen the throttle adjusting screw slightly, so that the engine speed is gradually reduced and the operation is stable, that is, the fan blades rotate evenly, and the blade profile (400 r/min) can be distinguished. If the adjustment fails, check the oil level from the inspection hole on the carburetor. If the oil level is too low, please adjust it. If all inspections are in good condition, continue to check the wiper tube and intake and exhaust manifold for cracks and air leakage. Remove the carburetor and blow the idle metering hole and idle air metering hole with compressed air. If it works normally after reassembly, the metering hole is blocked.

When the engine is idling, the speed is higher than the normal range and cannot be reduced by adjustment. This is the problem of excessive idle speed. When the engine idle speed is too high, park the car on the flat ground and press the choke button and manual acceleration button to check. Press the throttle rocker arm by hand to close the throttle. If the idle speed is normal, it means that the lever spring of carburetor is too soft. If pressing the throttle rocker arm is ineffective, check whether the throttle shaft is loose or whether the throttle is closed. If the throttle valve is normal, adjust the idle speed with the idle speed adjusting screw.