Most car engine carburetor has needle valve that controls the precise flow of gas on the float bowl. Controlling enough gas flow will ensure proper function of the car engine’s carburetor. If the float bowl has too much gas, it may flood the carburetor making it malfunction. On the other hand, having too little gas may also damage the carburetor not allowing it to start at all. Checking your carburetor to see if all parts are intact and functioning on its desired performance should be done every now and then. Checking your carburetor can be easy and only requires little technical experience from the person doing it.
To facilitate, you will need the carburetor’s repair manual, socket set, wrench, screwdrivers, carburetor’s cleaner and tachometer. Initially, apply emergency brake on your vehicle and make sure that the transmission is set on park or neutral. Disconnect the negative cable of your battery.
Remove the cover of the air cleaner (air cleaner housing) by loosening the bolt and frame through twisting the butterfly nut. Remove the screws attached to the body and base of the carburetor. Hook one end of the tachometer to the bare metal source of the engine. Connect the other end to the negative side of the ignition coil. Connect the negative battery cable and start the engine. Warm the engine up until the valve opens on the carburetor.
By placing a screwdriver on the mixture screw, turn it clockwise. See if the RPM reading on the tachometer changes. If no significant change happens even if you fully turn the screw, the needle valve may not be in place or has failed to properly seat. If this is the case, turn off the engine and once again disconnect the negative battery cable.
Remove the mixture screw using a screwdriver. Pull the needle valve and examine its tip if it’s dirty or bent. It should be tapered and clean; replacement is needed if it is bent or damaged. If certain deposit is seen, cleaning it will do the trick How To Clean The Needle Valve On Carburetor. Make sure that all deposits are removed and no damage has been made to the valve to ensure proper function.
You must also check the gasket inside the carburetor seat. If it is crushed or cracked, replace it right away. Clean the carburetor by using a carburetor cleaner making sure that all carbon and sludge are removed.
Return pieces back making sure that all pieces goes to where you took it off. Redo the check by using the tachometer and reading the RPM of the carburetor. If changes appear when the screw is adjusted and the RPM drops reading, the valve is properly functioning. If no changes happened, there might be a need to replace it.
Since carburetor needle valves are prone to dirt and deposits, cleaning it regularly can ensure its proper function and decrease the chance of it being damaged. If you are not certain that you can do this on your own, having it done by a technician should be your option.