Runs wide open when started and stays that way

There is no variable throttle control for this model i.e there is no lever for engine throttle on the handle bar?

If yes, then engine speed is fixed and open throttle is normal.

The motion of the linkage is merely movement of the governor mechanism. Wide open is normal when engine is not running. The governor will close down the throttle as engine starts and reaches the fixed operating speed. There will be adjustments but on a fixed speed model only the running speed is considered adjustable.

The MTD engine service manual is available at the following URL for no fee.


https://www.mymowerparts.com/pdf/MTD-Service-Repair-Manuals/MTD-REPAIR-MANUAL-FOR-P90-ENGINE-769_06294_p90_engine.pdf

WARNING Improper adjustments of the governor and carburetor linkage may lead to catastrophic engine failures.

Some saws have a throttle lock that locks the trigger to aid starting. Get a look at the carb to see if it opens when the trigger is pressed and closes when the trigger is released. If it stays open the lock may not be releasing or the throttle linkage is bound up or disconnected from the carb.

The way i set the govenor is, slacken the screw on the engine govenor arm, push the arm fully over to open the throttle wide open, now turn the actual govenor shaft within the arm in the same direction, fully retighten the govenor arm screw,

Try adjusting the spring to the throttle. This would be on the carb and what the governor attaches to. The spring will be contected to the throttle and an anchor point that you would be able to bend slightly. I would also check to make sure the connector on the throttle shaft on the carburetor is in the correct hole. Hope this helps!

It sounds like the govenor spring has become disconnected or the clamp on the governor shaft has become loose and allowed the linkage to get out of adjustment. If problem has occurred suddenly it could mean the governor gear assembly inside the engine has broken and means the engine will need to be dismantrel to replace the governor gear assembly.
Check throttle linkage to see if spring is attached at both ends, one end on the throttle linkage and the other at the fixed point on the engine or to the end of the speed control lever. With engine stopped the spring should hold the throttle wide open and hand pressure on the linkage shoud be all that is needed to move throttle shaft closed to the idle position with no binding in the movement of the linkage.
If spring is OK and while engine is running, linkage should be able to be be moved to bring engine back to idle. If porblem has occurred gradually, then linkage will need re-adjusting. Loosen adjusting clamp on governor shaft, then holding linkage in wide open throttle position rotate shaft as far as it will go in the opposite direction to that requred to close throttle to idle . Re-tighten clamp.

your govenor linkage is on wrong remove the link and install it the proper way...good l uck

I had the same problem and what I did fixed mine. I got it running with the starter fluid then pushed the linkage (Rod) on top of the carb and ran the engine wide open (by pushing the linkage), then released... then wide open again. I did this 4 or 5 times. Then to my suprise something clicked in the carb and it began to run normal. I have alot of experience with car engines, but not small engines therefore this had me baffled. I feel I got lucky in the repair, because something within the carb was stuck. You can not just run it wide open using the throttle...you have to push the linkage (I guess it bypasses something). Hey it worked for me. I wish you good luck and let me know if I can help in any way.

go to sears.com and look up the actual engine number. they have a section for lawn and garden and in there there is a link to their parts lookup and they are very detailed. but you will need a pulse tach to set the govenor back to where it was and if it spun the govenor open too far due to the govenor not being hooked up, it could have came apart inside the motor and you will need to take it to a shop. as far as setting the govenor once you get it all back together, you need to push the throtle wide open and turn the govenor shaft in the same direction then tighten it down. yeah its not hard if you have done it before but if you havent and cant understand what i just said, save your time, and engine and have a shop fix it. and i havent seen a motor in my 9+ years that you had to remove all of that to fix a recoil rope.

You want the spring to hold tension against the governor.

Hello:

The Carbuertor Throttle is Held in the Full Open Position Until the Engine is Started and Running, then the Governor and Spring Work together to Keep the Engine RPMs to the Desired Setting.
The Following is an Explaination on How the Governor System on Small Engines Function.
>>The Governor System behaves like an Unending Tug of War between One of Two Governor Springs, which Pull the Throttle Toward the Open Position, and a Spinning Crankshaft, which Tries to Close the Throttle. When the Load on the Engine Increases - a Typical Example is when you Move your Running Lawn Mower from the Driveway to the Grass - Crankshaft Revolutions Drop. But the Governor Spring is Still Tugging, Causing the Throttle Plate to Open. In Response, a Larger Volume of Air-Fuel Mixture Enters the Carburetor, Increasing Engine Speed to Compensate for the Increased Load. The Crankshaft Speeds Up, and the Tug of War Resumes, until a New Equilibrium is Achieved. With Each Change in Load, the Tension Between the Governor Spring and the Load Brings about a New Equilibrium, known as the Engine's Governed Speed. Neither Side Wins until the Engine is Shut Off. At that Point, without the Crankshaft Spinning, the Governor Spring Pulls the Throttle to the Wide-Open Position. Two Types of Governors are Common on Small Engines - Mechanical and Pneumatic.
Please, Do Not Hesitate, If you Hit a Snag or this Does Not Correct the Problem, I am Here if You Require More Assistance.
Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Be Happy. Thanks.

Good Luck

Respectfully

jbridger (John)