Gx120 carb running choke only

Discussion in 'Mechanic and Repair' started by precision8m, Feb 24, 2013.

  1. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,249

    As I recall, some GX120's are equipped with a fuel strainer(sediment cup) incorporated into the carburetor, some are not--it depends on the vintage and SN of the engine. If yours happens to be so equipped, remove and make sure it's clean to prevent further problems down the road.
  2. precision8m

    precision8m LawnSite Senior Member
    Messages: 349

    I have already confirmed that plenty fuel is flowing into the fuel bowl with no restrictions. There is only a little filter at the bottom of the gas tank at the beginning of the line that leads to the carb. Fuel flows into the bowl quite easily. For $20 I can get a new carb with a 3 year warranty off ebay. Sounds like that may be my next step.
  3. pugs

    pugs LawnSite Gold Member
    Messages: 3,025

    You wont be getting a Honda carb for that. Some junk aftermarket one maybe.

    Honestly its rare on a GX120-390 that I need to replace a carb for the problem you have. You should be able to clean it. Have you had the jet and emulsion tube out? Have you cleaned the bowl as well? Could the problem be something other than fuel?

    Only time I have had to replace them is if they wont idle right and no amount of cleaning seems to make a difference on the idle side of the carb sometimes. But on the high speed side even the dirtiest carb should run after cleaning for Honda GX's anyway.
  4. precision8m

    precision8m LawnSite Senior Member
    Messages: 349

    I don't know what else the problem could be. It runs on no choke if you spray carb cleaner but on its own it only runs at full choke (and runs strong too). I cleaned ALL parts that involve the whole carb - bowl, jets, etc. I tried to remove the main jet but it wouldn't come out with moderate force and I didn't want to strip out the head. I did ensure that it flowed very well by spraying through it liberally.

    Thanks for all your help. I'll look into a real Honda carb.
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  5. precision8m

    precision8m LawnSite Senior Member
    Messages: 349

    60 something for a new genuine Honda carb. Seems easier than fooling with it forever.
    Posted via Mobile Device
  6. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,249

    Precision, it isn't a surprise you're not having any luck if you haven't yet removed the main jet and emulsion tube. If the main jet is tough to get out, you will need a screw driver bit(preferrably one that is hollow ground, not tapered), that, as nearly as possible, fills the slot in the main jet. Yea, some can be tough but I've never failed to get the main jet out of a Honda carb.

    Like Pugs, I have had no trouble cleaning up a Honda carb.

    Pick your own poison--what have you got to lose in giving it a shot particularly if you're willing to part with $60 for a new carb.
  7. herler

    herler LawnSite Fanatic
    Messages: 5,139

    One other possible problem could be the gasket between the carburetor and the intake might be sucking air, which would explain why it runs strong on full choke, either way if the carburetor has come off there's a good chance a new gasket is in order... And if your engine has a spacer there might be two gaskets, but hopefully it's just one.

    We do want to at least try and eliminate all possibles before spending $50 to $80 on a new carburetor.

    For sure, if you order up a new carburetor, get a gasket as well...

    If that guy on ebay has more than one and you're not leery of sharing, I'd like to see this $20 carb.

    Well, I hate to spend it too but believe me I have been there and cussed and fussed until...
    Only experience tells me, sometimes it's best to just order up new.

    And with carburetors AND coils, even if you order it and then it turns out the old one's still good...
    It never hurts to have a spare.
    I always wrap them in a ziploc baggie for storage.
    Last edited: Feb 25, 2013
  8. precision8m

    precision8m LawnSite Senior Member
    Messages: 349

  9. robert@honda

    robert@honda LawnSite Member
    from Atlanta
    Messages: 154

    Here is the definitive guide to cleaning a Honda carburetor (.PDF file):

    How To Clean A Honda Carburetor

    That said, your time is worth something, especially if the equipment that's down isn't making you money. A new carb from Honda runs about $65. Have the serial number from the engine block if you buy one; it will make it easy for the parts guy to find the correct carb quickly. (There are a number of different part numbers for the GX120 engine's carb, depending on which version of the engine you have).

    Caveat: I work for Honda, but the preceding is my opinion alone.
  10. precision8m

    precision8m LawnSite Senior Member
    Messages: 349

    That is on another forum. I cant access the info.

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