Hit the throttle it quits running . it starts right up fast idle ok cuts good .wide open throttle runs fine. let it idle and hit the throttle it dies, starts right back up. has new carb kit, fuel, spark plug,rubber intake boot and clamp ,air filter ok ,fuel line not leaking,

You reported that most of the items I would've suggested, you have checked...
Good job.
A couple more things:

• Replace fuel filter, it's in the gas tank
• Check and clean the Spark Arrestor screen at muffler, when they plug up, it's a major restriction to exhaust gas flow
• And check and adjust High/Low screws at carburetor, video attached.
• And clean or install rebuild kit for carburetor

Good luck...

One more...

Throttle spring came undone or something is stuck in the air gate/cetrifugal lever that controls the throttle.

which engine,? the have up to 3 choices.
rih?
what are the full symptoms,
did you do the full listed 60k mile tune up on car?
sparkplugs,wire, cap rotor/filters? no engine runs right with bad spark
unless it's a diesel.
starts good
runs good or bad hot or cold engine
idle at 800 RPM hot?
stalls> when hot and cold engine
lost of power
bogging
misfire,
learchs>

only stalls , but runs perfect even up hills, at wide open throttle.
fresh gas, or 1 year old?fuel.
can your fast right foot , save the stall, and easily?

ok stalls 101.
1; lost 12vdc to EFI system.
2: lost engine compression.
3: lost spark.
4: lost fueling or floods
there is a simple test for each.
do you want more guesses, or how to do tests.
can do both, but my guessing fails 99 /100 times.

tune it up
do the right foot test. those are always first. on stalls.
always.

Kescorpio56:
Check your throttle and choke settings. Something is causing the throttle plate in the carburetor to remain open or the governor is improperly set. I would reset the air/fuel mixture screws to one and a quarter turns out and back the idle screw all the way out. Make sure that the throttle cable operates the throttle properly and check the governor setting and reset the governor setting if needed. Start the engine and adjust from there. When the engine starts, adjust the idle screw until the engine idles. Adjust the fuel/air mixture screws for the best idle. Then run the RPM up and adjust the fuel/air mixture screws for the best run/idle combination. Don't forget to adjust the governor if the engine runs too fast or too slowly.

There are two needle screws that can be adjusted to make the engine run properly. Be certain that the carburetor is clean and the diaphragm is in good condition, and the fuel is new. The two needle screws mentioned above should initially be adjusted at one turn open from turned in all the way (lightly seated). Each of these needle screws performs different functions. One is for idle and throttle response (this screw is marked "L" and the other screw is marked "H". L and H are marked on the carburetor body and also on the plastic "shroud" near the adjustment screws. These screws are not interchangeable, being foolproof since the thread sizes are not the same. When properly adjusted the low speed screw (L) allows the engine to idle properly and throttle response will work properly. When the high speed screw is adjusted properly the engine will have correct power at full speed. Adjust the low speed screw so that the engine idles and when you squeeze throttle all the way to wide open the engine should not hesitate and should come up to full speed and when you drop the throttle it should idle nicely without stalling. Now adjust the high speed screw. Hold throttle wide open, holding it there while you adjust the high speed screw. If this scares you (be carefully so that the spinning chain does not cut you!) you may adjust the high speed screw at idle, turning it just slightly in or out. The high speed screw should be adjusted so that the engine does not run clean at wide open throttle but sputters slightly, slightly adjusted open from running clean to slightly sputtering. When under load (cutting a log) the engine should run clean. Good luck!

Throttle Position Sensor

Wears where you use it most

lots of things it could be........check the obvious first

1.....throttle butterfly to see if it had come out of the carburetor
2.....check static governor settings. to set rotate carb to wide open throttle, loosen governor arm and rotate it to the right, tighten jam nut, if it still runs away then you have a blown governor inside the mower
3..... check for unhooked springs and linkages
hope this helps and good luck the above 3 things to check is 90 percent of all my repairs in the shop when it comes to the engine running too fast

see ya!

throttle position is relative to to the size and hardness of what you are cutting. the thicker the wood the more throttle is required. to run the saw wide open is not allways best

you need to take your air filter off and look into the throat of the carbruetor to see if the ""Butterfly""
is still intact and working not the choke butterfly its the one closest to the engine that moves with the throttle and be sure it is still there and moves as you move the throttle.... open is horizontal and closed is not quite 90 Degrees. check to see it is tight and in the center if the throat when closed.
you may have to remove the carb. to see it function more clearly
make sure the throttle cable is free and not binding any where and to be sure of its adjustment to allow the throttle to return to the idle position.
lubricate the cable from the trigger to carb. wd 40 is ok.
if all above is ok then find the L on the carb. and ccw it 1/8 turn to ritchen it alittle to help slow the idle down some to a respectable level

Try balancing ans syncronising the carbs.
BALANCE THE CARBS
Turn the throttle screw on the LEFT carb one half turn inward. Now start the engine and get it warmed up. With the engine running, remove the RIGHT spark plug wire. Adjust the idle speed on the left carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Now turn the throttle screw on the RIGHT carb one half turn inward. Restart and rev the engine. Next, remove the LEFT spark plug wire. Adjust the idle speed on the right carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Turn the idle screw on each carb EXACTLY ONE QUARTER turn outward and restart the engine. The engine will be probably be idling very fast. Adjust both the idle screws equally from this point to get to the desired idle speed.

SYNCHRONIZE THE CARBS
Remove the air filter and rubber fittings to allow you to see into the throat of both carbs. You may need a mirror to see inside. You need to be able to see the slides go up and down when you twist the throttle. Now turn the fitting where the cable goes into each carb such that there is just a bit of slack in the cable, 1/16" is plenty. Lock ONE of the cable adjusters down tight. All further adjustments will be made on the other carb.

With the motor turned off twist the throttle very slowly while looking at the slides. Both slides need to begin lifting at the exact same moment. If the slides don't raise at the exact same time then slowly twist the throttle until the locked adjuster slide just barely starts to move. Hold the throttle still and turn the adjuster on the other carb so that the slide on that carb just barely starts to move also. Now recheck the slide movement timing. Do this process until the slides on both carbs begin to raise at the EXACT same moment. Lock down the loose adjuster and re-check the slides.

Please rate this solution. Thanks!