Mantis tiller - dies when throttle is pulled

[pashworth]

Hey everybody! Long time since I posted here, but I need some help.

I have a 4 year old Mantis 2 cycle (oil and gas) rototiller. It has worked great until this season. Althought last year I did have some problems getting it running as I left some gas it in over the winter. The small engine repair place donw the road stated it only take a little of the ethanol "improved" gas to really screw up the piston and rings. True?

Now for this year..... starts with the few presses on the bubble primmer and a few pulls. But when it is running as soon as I lightly press the throttle it dies and stops running. The low adjustment screw seems to work as when I turn it the rpms change. When I turn (either direction) on the high adjustement screw, nothing.

Everything I have tried will not allow me to give it any gas to get it running full speed.

Any help / thoughts?

Regards,
Paul

 

[Bird]

Paul, my 2-cycle Mantis also turned 4 years old this past month. I bought it direct from the company as a "refurbished" model, although it looked new. Do you have the Owner's Manual for yours? Page 7, item #9 on starting says in part when it starts "Let the engine warm up two to three minutes before using." And they mean that literally! As with yours, any attempt to use the throttle until it has been sitting there running for at least two minutes will result in it instantly dying. If you're standing there waiting to get to work, two minutes can seem like a long time. But then it runs great after it's warmed up.

The only time I've needed to adjust the carburetor was when it wouldn't start a couple of years ago. I followed the directions on Page 12 of the manual and all was well again. And yep, I've noticed the same thing with the high and low speed adjustment screws. To start with, it says to turn the RED high speed screw counter-clockwise all the way to stop, then the WHITE low speed half way to get it running and warmed up for the final adjustment. Mine has never needed anything beyond that. But it doesn't seem that turning that RED screw changes anything.:laughing: Oh well, it works fine anyway.

Incidentally, the first winter, I ran all the gas out of it, then in the Spring, no gas would go through the fuel filter. It seemed to have hardened, but when I took it out and gave it one quick reverse direction blast with the air hose, all was well. So in spite of the horror stories about ethanol, I leave gas in my Mantis year round. I do try to remember to start it and let it run 10 to 15 minutes about once a month.

I don't know whether this will help you or not, but I guess the only advice I can give you is to have more patience when it starts.:laughing: At least your "problem" sounds normal to me. It did annoy me for awhile until I learned to give it time. And if you shut it off, it doesn't take long for it to cool and you have to follow that cold starting procedure again on mine.

 

[Soundguy]

sounds about right... let it warm then try it.

I have a couple weedwackers that ar elike this..

either flood out or starve till warmed up..

soundguy

 

[TedLaRue]

If, after letting it warm up, it still won't run at high speed or it seems to lack power, check for a clogged spark arrester screen in the muffler. My tiller is a little older than yours, so I can't swear you have a spark arrester screen, but you probably do.

The restriction in the exhaust from a clogged screen can cause the behavior you're describing as well as a general lack of power. The screen clogs up with oily carbon which is difficult to remove with a solvent. You're better off cleaning it by scratching it with something sharp. I finally took the screen out of mine. I don't use the tiller where there is a fire hazard.

If none of our other advice helps, you probably need to rebuild (or at least clean) the carburetor. If you can get it apart without tearing any of the gaskets or diaphragms, you may get by with just cleaning it with some carburetor cleaner (my favorite is Berryman Product's Chemtool Carburetor Cleaner).

A side note in case someone doesn't know, the Mantis tiller is made by Echo sort of like the way a Chevy Prizm is actually a Toyota Corolla.

 

[PapaPerk]

I'm pretty sure your carb is gummed up with old gas. The engine on Mantis tiller is sensitive to gas being left in it. The engine is made by Echo by the way.

I suggest disassembling the carb and cleaning it well with carb cleaner. You may buy a rebuild kit for it and install the new parts. Not very expensive. The diaphragm in the carb can harden and not work correctly.

Because your machine is only 4 years old I bet it's carb just needs a good cleaning. Mine did! These little buggers are irritating as heck when not running right. But when they run man can they dig! While you are in there make sure to install a new air filter.

Good luck!

 

[2458n]

At one time I thought I had cornered the Mantis tiller market. Bought every one at auction I could find. They are great tools when running. This said I am sure many people have died trying to start them after several years of use. Even the manufacture offers a Honda engine for about a hundred dollars more. The best - most reliable one I gave to my mother. It was electric.

 

[pashworth]

Thanks for the help and input guys! I will try letting it run for longer at idle than I usually do and remove the air filter and spark arrestor to see what happens. I'll post after I get to mess with it on Sunday.
Thanks again!
Paul

 

[pashworth]

No difference in the way it runs after letting it warm up for 2o minutes. I thought it was air starved also so I removed the air filter and cover..... same thing.

I guess I am going to buy a new carb. If I am understanding it correctly there is no way to pull apart the carb, as it is one single block.

Paul

 

[hawkeye08]

try to get some carb cleaner in there (can you get the fuel line off the carb and spray some in there). try and start it to pull the cleaner in, then let it sit for overnight and give it a try. I have used Lucas fuel injector cleaner in the gas for generator with good results, Seafoam has also worked. It is just gummed up..

 

[Bird]

No difference in the way it runs after letting it warm up for 2o minutes. I thought it was air starved also so I removed the air filter and cover..... same thing.

I guess I am going to buy a new carb. If I am understanding it correctly there is no way to pull apart the carb, as it is one single block.

Paul

Darn it, I thought sure we'd solved that one. But I've no experience with replacing, or working on, the carb beyond the 2 adjustment screws.

 

[2manyrocks]

Not having a Mantis, I can't say for sure, but most 2 stroke carbs I've seen have four screws holding a plate on them that contains the fuel pump diaphram. I'd look for a parts schematic for your model and see if there isn't a carb kit for it.

Today's rotten gas will foul a carb in a month.

While your at it, be sure to check all your fuel lines because methanol will ruin them too, if they weren't designed for it.

 

[Bird]

I guess I am going to buy a new carb. If I am understanding it correctly there is no way to pull apart the carb, as it is one single block.

Not having a Mantis, I can't say for sure, but most 2 stroke carbs I've seen have four screws holding a plate on them that contains the fuel pump diaphram. I'd look for a parts schematic for your model and see if there isn't a carb kit for it.

I figured Paul & I had the same model, but that may not be the case. However, page 17 of my owner's manual shows "SV-5C/2 ENGINE PARTS ASSEMBLIES CARBURETOR" and shows an exploded view of the carb and a parts list (38 parts) which includes a part number A021001090 for "Carburetor - C1U-K82" for the whole thing and part number 12530013120 for "Repair Kit - includes items 24-33" so yes, you can take it apart and overhaul it if it's the same as mine.

But at least, Paul, those numbers should tell whether we have the same machine or not.

 

[Soundguy]

if it was built.. I'm surprised it can't be rebuilt.

even if a monolithic block.. there must be galley plugs for drilling the jets..e tc.

soundguy

 

[PapaPerk]

You can certainly rebuild the carb! You don't even need to do that. Just disassemble, clean, and reassemble. Should run fine after that! Good luck

 

[bilrus61]

We've had our Echo engine Mantis for about ten years. Runs great. I basically use it as a edger for our driveway and sidewalks. Get some carb cleaner and let it just idle. Check the muffler and see if a dirt dobber wasp has clogged it up. You can run some trimmer line into the muffler to clean out any wasp mud. Just a tad of mud will restrict your airflow.

 

[RonMar]

There is an internal rubber diaphram, and some acetate membranes that act as check valves. These get old and dry out/get stiff. 4 years sounds about right, if you left fuel set in it for any length of time. the rubber diaphram modulates the needle valve used above idle, so that is probably your issue.

They are actually fairly simple to overhaul. The carbs are basically similar to the walbro series carbs, if it isn't an actual one. If you google the P/N stamped on the carburettor you can probably determine the actual manufacturer. If you go onto Youtube and search walbro carb setup, overhaul or tuning, there are several videos that walk you thru overhaul and tuning these simple carbs. There are also some mantis specific maintenance and troubleshooting videos that might help you...

Good Luck

 

[2manyrocks]

The good news it is a Mantis and so it's probably a common carb and not some mystery carb from places unknown.

 

[Jim Thompson]

The good news it is a Mantis and so it's probably a common carb and not some mystery carb from places unknown.

Zama C1U is a very common carburetor and pretty easy to service. Same carb that a lot of Echo equipment uses. I used to buy the fuel pump diaphragm and metering diaphragm by the ten pack. Most of the time you don't have to remove the clean out plugs, but if you do, be sure to reseal them. I use clear fingernail polish.
I would suggest going the the Zama web site and click on the technical section for lots of good info.

Jim