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Mantis tiller- carb won't prime


jptra's Avatar
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10-27-14, 10:24 AM   #1  
Mantis tiller- carb won't prime

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!

 
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10-27-14, 10:50 AM   #2  
I'd say you pretty well have it figured out. Take the primer assembly off and run the inlet line into fuel and see if it works off the machine. You may have a bad primer check valve. The fuel emptying into air wouldn't make any difference.

You just replaced the bulb itself and not the rest of it? Those things aren't very expensive. You can get them off Ebay.

 
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10-27-14, 11:47 AM   #3  
Hello, thanks for your reply. Yes, I just replaced the bulb only so far. You are saying to just replace the whole primer base? I was thinking that was the next step, as I could not find the check valves themselves.

I can try primer base assembly by itself, but I want to make sure I understand what you're suggesting. The fuel intake line is on the carb body itself, and not on the primer, right? Only the outlet line is on the primer base assembly.

 
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10-27-14, 01:03 PM   #4  
Might try spraying some carb cleaner through the circuit, it might be stuck with varnish. You might get lucky and it will come loose. Have a good one. Geo

 
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10-27-14, 03:34 PM   #5  
Yours is the carb with the primer built in. Go with what Geo has suggested. You wouldn't be able to take off the assembly to test it. The check ball could very well stuck with varnish and the carb cleaner should shake it loose.

If you don't have a filter on the fuel line, it would be a good idea to install one.

 
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10-27-14, 05:45 PM   #6  
Ah yes, after a little more research I understand now you were speaking about a remote primer setup.

Yes, mine is the built-in primer, the exact part being shown here:

Genuine Zama A056012 Primer Base | eBay

I'm guessing the bad check valve on mine is the larger metal "button" (just under the primer bulb). I did try spraying and even briefly soaking the whole carb, including primer base, in carb cleaner initially, in an attempt (successful!) to fix poor engine performance. Maybe that caused a problem? I'm also guessing this check valve cannot be replaced, and a new primer base has to be bought? Looks like it's about $14, so it won't break the bank if that's the case.

Thx again for your responses and suggestions!

 
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10-27-14, 07:35 PM   #7  
You might be able to replace the carb for a few $ more than the base. have a good one. Geo

 
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