I have a four year old mantis tiller with a two stroke single cylinder engine with a ZAMA diaphragm model C1U type carburetor. It starts Ok, but wont run. If it runs, it won't run high speed, like its flooding and it dies. Pull and choke, pull and no choke and it starts but wont stay running.
On year two the carb was rebuilt (at a shop) because I left fuel in the tank over the winter, bad boy. I did it this year again so I put the gasket and diaphram in (rebuilt). Good job, it started but wont stay running. Muffler is not clogged. The fuel line is sucking air, I THINK. from the fuel filter and tu beassembly it plugs in the 3-hole plug that exits the side of the fuel tank. A separate 3 inch tube goes to the intake of the carb. Is this suppose to be one continuous hose, no break in it? Looks like at one time it was one 8-inch tube, fuel filter to carb. Could this be causing an air leak? Tubing is sort of brittle. Will replace when I get some tubing. Think this will cure it? f not I'll be back tomorrow.

KEN (kwahl1atsbcglobaldotnet)

 

It should have no breaks in the lines. Sounds like they need to be replaced and the carb may require cleaning.

 

Replaced the fuel line. One continuous line again. Not the fix. Does the same thing. It starts runs for 5 seconds and dies. It is starving for fuel after those 5 seconds. I can quickly chike it, then unchoke it, and it'll run for 5 more seconds, and dies. I have rebuilt the carb. and was very certain things were going back together as they should. I'm thinking the needle is not working right, so I'll tackle that tomorrow. Or any other suggestion would be appreciated. This is not that difficult!

 

When you say you rebuilt the carb, what did you do? The carb still has a restriction. You never mentioned cleaning it.

 

I put the gasket and diapham kit in it. Comes with the main valve with spring. Fairly easy stuff. but I'll darn if the thing won't keep running. Dirty. Something upside down? main needle valve adjustment?

Help

 

Get yourself a good can of automotive spray carburetor cleaner and take the carb back apart and clean out/spray through every little passage on it. Take the mixture adjustment screws out too and clean the holes they go in. Clean out the filter screen in the carb too.