Disconnect the wire tip from the valve terminal (for clarity, the air filter housing has been removed).
We apply 12V from the battery to the valve terminal (the "minus" of the battery is connected to the car body). If a click is clearly heard, the valve is working properly.
You can also check the valve after removing it by connecting its terminal to the positive terminal of the battery and touching the car ground with its body. A working valve will make a distinct click and its shut-off needle will be pulled into the body by 2–4 mm. Replace the faulty valve.
Using a 13 mm wrench, unscrew the valve.
Idle jet from an old valve (if the new one has a different marking) we wash it in acetone, blow it out with compressed air and transfer it to a new valve.
We screw the new valve into the carburetor "by hand", making sure that the rubber sealing ring is in place and not damaged. We start the engine and, if it runs unevenly at idle or stalls(signs of a leaky valve seat), we slightly tighten the valve with a 13 mm wrench.
When the power wire is disconnected from the valve terminal, the running engine should stop.