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Mantis 20 Tiller - Zama Carb question

Discussion in 'Mechanic and Repair' started by abl1111, Jul 20, 2010.

  1. abl1111

    abl1111 LawnSite Member
    Posts: 16

    Have an older Mantis 20 with a Zama carb. Got it running nicely, but the push-primer wasn't filling with gas. So I figured I'd fix it. Mistake! Took primer off and the base its mounted on which is mounted to the carb ( directly under this base is a carb diaphram ).

    Poked through a few of the holes in this base to clear out gunk - used compressor too. Put back together - gas flowing in primer now, but motor won't start. When motor turns over for a second, gas leaks from carb.

    I think I blew it and must have punctured something in that primer base.

    Can anyone confirm ?

  2. madmower

    madmower LawnSite Member
    Posts: 43

    replace carb or find a second hand replacement to use as spares

    next time get the carb ultrasonic cleaned i never poke any thing in a carb just drop it in the ultrasonic cleaner when the bell rings carb is clean just replace the gaskets & diaphrams and cab is ready to refit

  3. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

    You didn't mention the carb numbers, but I'd guess it's a C1Q. The white base that the primer bulb fits against contains two check valves, one that permits fuel/air to be sucked into the primer bulb and one that allows fuel/air to be purged from the bulb. Care must be taken in cleaning those up. I rarely use air, particularly high pressure air. Pressure and solvent in the form or carb/choke cleaner works better and is less likely to do damage.

    You can go to Zama's website with the carb numbers to find the part number for the base, then order either online or dealer. For around $20 you can replace the base and install a new carb kit.

    I guess I'm too "old school" to just throw on a new carb. I've worked on 2/4 stroke hand held equipment for 20+ years and have replaced only one carb and that was on a new Echo trimmer right out of the box that wouldn't run properly even with adjustments. Of course that was a warranty.

    On the other hand, if a person is not capable/comfortable in tearing down/rebuilding a carb as opposed to taking to a shop, replacing the carb is not a bad choice when you consider the labor charge.
  4. abl1111

    abl1111 LawnSite Member
    Posts: 16

    Thx for the reply -

    YUP - I blew it then ! Damn ! I'll try to go to a local mower shop to get the parts and kit.

    I am a newbie with rebuilding carbs - I always get a bit confused with proper alignment of the " flap, spring and needle valve ". Also, I have never taken out welch plugs...
  5. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

  6. abl1111

    abl1111 LawnSite Member
    Posts: 16

    Ok. Bought a carb rebuild kit and the primer base. Replaced the primer base first just to see how she ran. No rebuild yet. She ran great. Tried to tweak /tune her better ( 1 1/4 turn out each and then played around a bit ). She was running great ( under a load ) for like 10 minutes and then started to lose power big time.

    This Mantis cultivator is a gimme from a friend so I know very little about it's history.

    The initial compression was 125 and I tested it again a few minutes after she was running poorly - so, hot, and it was 115-118'ish.

    She usually would start right up either way. Some times it was a little tougher.

    She would run like crap and then a minute later, run perfectly strong again. When it was running weak, when I pressed the throttle, she would bog and stall. She usually idled well... And so it went. I tried to tweak the "L" on the carb, turning it out a bit more. It seemed to help. I stopped playing with it when it was running well ( besides it has been 90-95 and HUMID every day here in NY - I was DONE ! )

    But, I know it will do the same thing tomorrow.

    What I have done thus far:

    - all new fuel hoses (3) of them
    - cleaned weighted fuel filter in gas tank
    - new primer base and bulb
    - cleaned air filter - it needs replacing
    - emptied old fuel and cleaned fuel tank by 'dooshing' several times w/ gas

    What does this sound like ?
  7. taxidermist

    taxidermist LawnSite Member
    Posts: 49

    For less than 50 you can buy a new carb. I just did a newer stihl fs55 string trimmer that would not pull gas with the primer bulb. I cleaned the carb and rebuilt the carb I got it running but it was sucking air thru the throttle shaft. I replaced the carb and runs like new.

  8. TurboMazda

    TurboMazda LawnSite Member
    Posts: 67

    Post the Crab Number model, I am sure one of the guys can help you better
  9. abl1111

    abl1111 LawnSite Member
    Posts: 16

    I believe the carb is a Zama K17, then it says 14Q directly under that stamp. I just took the carb off the machine today.

    I had used the cultivator today - it was running great. Then, after 10 minutes, I turned it off to remove roots tangled in the tines. I could not re-start it. I pulled the spark plug and it was bone dry ( no gas )...

    As for buying a new carb - I'd like to try rebuilding theone I have first ( I already own the kit ). Should I also try to R/R the pressed in pcs of the carb ?

    What'cha think ?
  10. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

    K17 is the model #, the body type can be found in at least a couple of different places, depending on the carb. Of all the Zama's I've worked on, the C1Q seems to be the most common, along with the RB rotary carb.

    Here is a link that should give you any help you need to rebuild the carb.


    I've seldom found it necessary to remove any of the pressed in parts except the welch plugs. I have found welch plugs loose inside the carb. You will have better luck seating the replacement welch plugs if you have the Zama tool kit. You need to be careful in removing welch plugs to avoid damage below.

    The the body type and model number are necessary to determine the proper rebuild kit.

    When you disassemble the carb, note the orientation and order to help in reassembly. With the problem you are experiencing, I wouldn't be surprised you'll find a plugged fuel screen although anything could happen.

    You may want to check the isoblock and gaskets(between the carb and block) for any apparent cracks/voids allowing the engine to suck air. If the engine will start and idle when cold, spray carb/choke cleaner around all the intake area. If the unit dies, particularly after warming up a bit to expose the leak, the engine will quickly quit die.

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