I have put this carby through the ultrasonic bath, I have cleaned the main jet and emulsion tube, and blown air through everything. Mower starts straight up but will only run on full choke. I usually just throw a new carby on when I get this problem but I figured I would see if I could solve this one. Any thoughts?
I don't know if you will find the problem Norm as you most likely have checked everything already but I guess you can double check everything in case something didn't get cleaned out enough.
Sometimes I get a carby that the holes are cleaned out but not to original size .
Occasionally I get a carby that is so rusted in the fuel line connector on the carby that you have to put a drill through and wire to make the hole back to the original size and push something through the hole for the needle and seat.
Same thing with the main jet you need to run the jet up and down fuse wire while you twist the jet, but I guess all has been checked already, when you leave the fuel bowl off and check how much fuel is leaking onto the base which most likely you've already checked.
They recommend to remove all the welsh plugs to clean the carby out and buy new plugs.
As we know sometimes you need a jet drill to check the size and you can even drill them the next size up.
The emulsion tube sometimes I need to push a single wire brush wire through all the holes to get them back to original size.
I also have to fully clean the brass part of the needle and seat that the needles side slides against as they can slightly stick.
When I look up the problem I get the following if you want to do a another check
If your mower starts but only runs with the choke fully engaged, it generally indicates an issue with the fuel-air mixture or a blockage in the carburetor. Here are some common reasons why this might be happening:
Lean Fuel Mixture: When the choke is on, it restricts air, effectively enriching the fuel mixture. If the mower runs only with the choke on, it may suggest that there isn't enough fuel reaching the carburetor or the combustion chamber when the choke is opened.
Clogged Jets: Even though you’ve cleaned the main jet and emulsion tube, there may still be a blockage or a partially obstructed jet that affects the fuel flow. Double-check that all passages are completely clear.
Float Issues: The float in the carburetor controls the fuel level. If the float is stuck, damaged, or incorrectly adjusted, it can prevent the proper amount of fuel from entering the carburetor.
Fuel Supply Issues: Ensure the fuel lines are clear and the fuel filter (if applicable) is clean. A clogged fuel filter or line can restrict fuel flow.
Gaskets and Seals: Check for any damaged gaskets or seals in the carburetor. If there’s an air leak, it can lead to a lean condition.
Idle Circuit Blockage: Some carburetors have an idle circuit that may be clogged. If this circuit is not allowing fuel to flow at lower RPMs, it can cause the engine to stall when the choke is released.
Incorrect Assembly: If the carburetor has been disassembled, ensure it has been reassembled correctly according to the manufacturer's specifications.
Air Filter: Make sure the air filter is clean and not obstructed, as this can affect air intake and ultimately the air-fuel mixture, leading to poor performance.
After you’ve addressed these areas, you can also try adjusting the carburetor’s idle mixture screw if applicable. Test the mower again to see if it runs properly without the choke engaged. If the problem persists, it may be beneficial to take further diagnostics measures.
This is a Honda carby clean below but is the same principle if you have missed something but from what we hear sometimes they just won't clear out and you need to buy a new carby.
Thanks Max, I have done all the standard cleaning on this carby, might give it another run through the ultrasonic, just curious as to why some carbys clean up fine and others don't
