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jptra

Mantis tiller- carb won't prime

jptra
9 years ago

Hi,

I have a Mantis tiller with a Zama C1U-K54 carb. The tiller runs great once started, and will run for as long as needed at both idle and high speed. However, the primer bulb does not pull fuel from the tank or fill up the primer bulb when depressed.

I have replaced the primer bulb, and checked the fuel lines, and there appear to be no holes or leaks there. I believe this may be the tell- when I hold my finger over the end of the purge fuel line that normally expels the fuel from the primer bulb into the fuel tank, the primer bulb will then fill up. I'm not a carb expert at all, but I'm guessing this means that maybe the outlet check valve is bad, and is preventing the vacuum necessary to draw fuel from the tank through the inlet check valve? When I put my finger over the hose end, I'm acting as a manual check valve?

Also, the purge line is very short, and just barely protrudes through the fuel line grommet of the tank, and into the tank. Therefore, it normally just empties out into air, and is not submerged in fuel. I did not modify this, so I'm guessing this is normal and should not normally cause a problem?

Am I correct in my diagnosis, and if so, can this check valve be bought separately, or is it necessary to buy an entire new primer base?

Thanks for any help and insight anyone can offer, and if anyone has a good, cheap source for the necessary parts to repair, it would also be much appreciated!

Comments (10)

  • loger_gw
    9 years ago

    Please post a pic of your bulb assembly. The one that IâÂÂll attach might have the black rubber part sold separate. Know itâÂÂs not a reed or flapper on the gasket that is the problem that might only come in a carb kit.

    Some cheaper primers appear self contained in a plastic housing that snap onto the housing vs the carb.

    IâÂÂll attach links to videos that could help in testing Etc.. I hope this helps.

    Two Cycle Fuel Line Help, 2 youtubs

    http://www.youtube.com/watch?v=uCC1qO75zDk

    = 2 Cycle fuel line sys types

    http://www.youtube.com/watch?v=Od9-PAjJY-0

    = Poulan 2150 line routing

    Here is a link that might be useful: Fuel Systems Info

  • jptra
    Original Author
    9 years ago

    Hi, thx for your response, and the links. They helped me understand the difference between a remote primer and built-in primer. Mine is the built-in primer, exactly as shown in the link below (~$14), and similar to the lower primer base shown in your picture. I'm guessing the bad check valve on mine is the larger metal "button" (just under the primer bulb). I'm also guessing this cannot be replaced, and a new primer base has to be bought?

    Here is a link that might be useful: Zama C1U-K54 carb primer base

  • loger_gw
    9 years ago

    I am not relating how the metal button could be the problem since metal is not likely a sealing material in a pump. Do you see a wear pattern on the disc that is saying the disc is not seating good? Do you have Small Engine Shops or Techs in your area? I feel this is a known problem that someone will share more on soon.

  • jptra
    Original Author
    9 years ago

    Hi Loger,

    I didn't mean to say that the metal button itself is the entire check valve, but rather that it acts as a cover/retainer for the outlet check valve. I believe the outlet check valve is the issue since I can place my finger over the purge line and the primer bulb will then fill.

    In the link I posted, you can see a small 2nd hole as well, which I guess must be the inlet check valve. You can't see it in that link, but I guess on the back side of that primer base you would see some type of cover/retainer for the inlet check valve as well.

  • loger_gw
    9 years ago

    A good diagram (which I c/n find) should answer a lot of questions. IâÂÂll see if I have a carb off or carb diagram that will show the circuit. Good Luck! IâÂÂll reply back no later than 4-6 hrs if I find any additional info. I also wonder if Echo would share a good link with you if you call 800# or Contact Us Email. There are plenty links online but I c/n spot one for this carb.

  • loger_gw
    9 years ago

    1. I found views of the current attached pics from the other sides. This could be of interest as possibly showing where check valves could be located. This might dictate that bulb mount replacement vs a repair.

    2. My kits that I am showing have serviced many carbs per pack. None shows what would be a valve or Duckbill valve IMO. I feel I have seen Duckbill valves in some plastic bulb assemblies. Plus, no carb kit in my collection has had diagrams.

  • jptra
    Original Author
    9 years ago

    Hi again Loger,

    thx for the legwork! Yes, I tend to agree that it looks like a primer base replacement may be the only way to go here. Either that, or I continue to use my finger to get that initial prime-LOL. Will report back if I get around to replacing the primer base to confirm repair.

    Thx again for all help!

  • loger_gw
    9 years ago

    I have no problem with my different methods of manual priming alternatives on my seldom used equipment. A small clear plastic eye dropper is #1 over this syringe with too much resistance.

    Hopefully someone will show us whatâÂÂs under the welch plug or seal that's part of the primer system. IâÂÂll eventually find an extra to open and share.

    Take Care!

  • Dorothy O
    3 years ago

    I have the same problem. Mine is new (used once last season after a mantis employee got it started and it did start again on that same day when home, but would never prime since. Will eat the loss and try another mfr :(

  • ssewalk1
    3 years ago

    Spray some starting fluid better yet carb cleaner in the air breather , if it will run .