Engine run @ half choke but will not run in run position

First , prime the priming bulb about 4 x...

Next put the choke lever in full choke position

Give a couple slow pulls, then a good strong pull...

(The unit should burp, run for a second)

Next put the choke lever in the half choke position

Pull rope

It should start and run, now put the choke lever all the way in the off position and let unit warm up a minute... if when you turn choke off it stalls out, u didn't warm it up enough...

It's too lean; not enough fuel mixed with the air. Look for the main mixture screw--it should be a large screw with a spring under it on the carburetor. Run the engine until it's warm.

With the engine running, turn the screw outward (lefty-loosey) about 1/8 turn slowly and see if it improves. Slowly turn the screw back and forth until it runs best with the choke completely off. Then set it 1/8 turn richer (turn screw outward 1/8 turn) than the best position.

Reason for doing this: Conditions change, even the barometric pressure. Small engines run okay if they are a little rich but not if they are a little lean.

Press primer bulb 6 times
Move throttle lever to start position
Move choke lever to full choke position
Pull starter rope sharply until engine attempts to start, but no more than 5 pulls.
Move choke lever to half choke position. Pull starter rope sharply engine runs. If engine hasn't started after 5 pulls, repeat all steps above.
After warming up for 10 seconds, move choke lever to run position.

Manuallib.com has a manual for this model available for free download

you can get guides online for error codes/ fault codes, wiring diagrams, schematic diagrams, torque specs, engine info, switches functioning, assemble, disassembly, complete refurbish, repair, installation every single thing is covered
within seconds u can get the access and it's totally illustrative complete
I know these websites

The next step is to richen the fuel mixture on the H screw on the carb, there is a special tool required to turn the adjuster screws because they have a splinr rather than a screw driver slot, the tool is part np. 530035560 unscrew tthe H screw 1/4 turn anti clockwise.

Normal starting practice is always done with the ignition on, primer as many times as it takes to 3/4 fill the bulb, move choke to full closed, crank engine until it fires once, move choke to half if there is a half position, crank engine until it starts and runs, move choke to full off.

if you are running the engine at full CHOKE, then it is flooding the engine, but if you meant off full choke, then the carb is still stopped up. Try soaking in carb cleaner overnight after removing jet & all rubber goods. HOPE THIS HELPS.

O and I are the international symbols for off and on. The O is the off position and the I is the on position. Put the switch in the I position. Make sure there is properly mixed fuel in the tank. Your Mantis probably uses fuel mixed 1 part 2cycle oil to 50 parts gasoline. Push the primer bulb a few times until you see fuel in the bulb. Position the choke lever to full choke, open the throttle completely and use short, quick pulls on the rope until the engine sputters. Reposition to choke to half and pull the rope again. The engine should start at this time. Let the engine run for a few seconds, then push the choke lever to off. Go to work in the garden.
Good luck!

You need to rebuild the carburetor. You will need to go to an outdoor power & equipment store of some kind to get a carburetor kit for your specific trimmer. It will come with various gaskets, (some of which you won't use), a needle valve, and a small screen that goes in the carb. Replace all old parts with new. New primer bulb is sold seperately. When you have the carb. apart, you will also need to clean the small ports with a Den Tek Brush (used for cleaning teeth). Use carb. cleaner when cleaning.

Jim

Most likely carburetor needs adjustment.