Mantis tiller carb adjustment problem

citytransplant · Sep 23, 2022

A neighbor mentioned he couldn't get his Mantis tiller to start. I told him I'd look at it

. Good spark, no fuel. The tank was dirtier than a pig in mud. The fuel filter blocked entirely and the carb looked as if it had just been dug out of the ground. I cleaned out the tank as best I could and installed new lines, filter, and a carb that I happened to have lying around. Fired up first pull. Problem is that it runs fine with the choke fully closed, but as soon as I open it, she stalls. I have both the low and high adjustment screws opened about 1 and 1/3 from dead closed. Shall I try adjusting one or both of these?

Thanks in advance.

Roadworthy · Sep 23, 2022

You've got options. My first thing to try would be Sea Foam. Drain the tank and make a 50-50 mix of fuel and Sea Foam (using the appropriate amount of oil if two stroke). Start the engine any way you can and let it run for a bit to be sure this mixture has run through the carburetor. Shut it off and let is sit for a day. Start it again and check results. If no joy let it sit another day and try again. It can take s few days for Sea Foam to work its magic but I've had really good luck with it. It sounds like one or more clogged passages in the carburetor so you're welcome to try the adjustments but if passages aren't clear you'll likely not succeed. From there my next step would be to replace the carburetor: mantis tiller carburetor: Search Result | eBay

5030 · Sep 23, 2022

Time to take the carb apart and give it a good soak in Berryman's Chem Tool or Gunk carb cleaner and blow out all the passages and jets and re assemble. You have crud (or jelled e-gas) in the idle circuit.

I do mine like Mustie on You Tube. I use a heated ultrasonic cleaner with Chem Tool in it.

Doughknob · Sep 23, 2022

Both the seafoam and carb cleaner/soak are right on. I might also open the low speed jet another 1/3rd and see what happens.

Tinhack · Sep 23, 2022

Only running with the chock on typically means it's not getting enough fuel--Choke lowers air supply to run on what fuel it is getting. I'd be looking at the main Jet or the mixing tube. If was as dirty as you say, I bet the bypass ports are also clogged.