Is it normal to turn off the throttle after washing and refueling?

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.

2. Unstable idle speed

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.

If the idle speed does not improve after the above maintenance, the fault may be caused by the engine. Usually, the gap between the intake valve rod and the guide pipe of the engine is too large, or the engine is close to overhaul, so the cylinder head should be removed for maintenance.

3. The cause of flameout may be unstable idle speed, but the idle speed is unstable. It may be idle motor fault. If the idle motor does not improve after replacement, check the intake manifold for air leakage from the throttle position. Because the air volume after air leakage is not a fixed value, ECU will intervene to adjust the idle speed, which will cause the idle speed to fluctuate up and down!