FH721D Engine runs WOT!!!!!

TheBrad83

LawnSite Member
Location
Tuscola
So I have adjusted governor, based on service manual. I have actually tried everything and every way. When I start engine and adjust throttle. It goes wide open, I removed governor arm and started engine. When I move governor shaft at idle, with nothing attracted. It does nothing. When the engine revs high, I pull back on governor arm and there is not tension. Is my governor bad?!?!
 

flintknapper

LawnSite Senior Member
So I have adjusted governor, based on service manual. I have actually tried everything and every way. When I start engine and adjust throttle. It goes wide open, I removed governor arm and started engine. When I move governor shaft at idle, with nothing attracted. It does nothing. When the engine revs high, I pull back on governor arm and there is not tension. Is my governor bad?!?!
Are you certain you adjusted the governor per the FSM (also setting the low and high idle via the control plate, throttle lever and control plate captured)?

Is the spring from the control plate to governor arm present?
 
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TheBrad83

LawnSite Member
Location
Tuscola
I followed service manual on adjusting shaft and plate counterclockwise. I moved the control plate all the way back. It was only way I could get throttle at idle at start up. Not sure how to set high and low. Please share any info, if u think I have missed something. Thanks!!!!
 

flintknapper

LawnSite Senior Member
We need to start with the Governor adjustment in a methodical way. Not saying you didn't do this...or that there might not be something wrong with your Governor, but the adjustment for some reason is easily misunderstood.

First thing to do is make certain your Choke and Butterflies on your carb are not sticking. Don't proceed until this has been confirmed.

Next check to see that the spring (long, thin, spring) that goes between the throttle link rod and Gov arm is in place (often they are missing).

With the throttle lever pushed to full speed (the lever that controls your cable),loosen the bolt on the Gov arm so that it can rotate freely on the Gov shaft (not moving the shaft).

Rotate the Gov arm up (counter clockwise) until the butterflies on the carb are fully open. Capture the arm in that position (l like to put a small wedge of wood under the Gov arm at the outer most part where the throttle link rod is). This will free up both of your hands for the next procedure.

Then rotate the governor shaft counter clockwise as far as it will go, you will feel it bottom out. Use a small pair of vice grips if you need to in order to be sure you have it all the way rotated to it's stop. Now while holding the shaft in that position, tighten the nut on the governor arm. You can now let go of the governor arm and reconnect the coil spring between your control plate and the Gov arm.

Once you have done that....we can look at setting your low and high idle speeds. That is done by adjusting an idle screw and moving the control plate up or down (on the right side only). A critical component of that (often overlooked) is first mating the throttle lever (at the control plate) to the control plate so it doesn't move when positioning the control plate to establish high idle. There are two holes that must be lined up and something of 6mm diameter inserted (drill bit, dowel, other).

But lets get the Governor done first...so we know that part is correct.

FH721DGovernorAdjustment.jpg
 
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TheBrad83

LawnSite Member
Location
Tuscola
Ok, so I did the governor arm adjustment as you described. I will double check tonight, maybe it’s the high and low that is incorrect. Question tho, does the governor shaft move very little? And with engine running and nothing connected to shaft. When I turn it, should the rpm go up and down?! Thanks for your help!!!
 

BigFish

LawnSite Fanatic
Location
chesapeake, va
The gov. shaft can move a bit, not much. when smartly turned CCW, you should hear a click/tap from the internal shaft arm hitting the gov. gear mechanism.
Turning the gov. shaft/arm , disconnected from the carb, will not cause an rpm change.
You need to peruse yer manual with serious intent. The gov. form and function is usually fully explained therein.
 

flintknapper

LawnSite Senior Member
Ok, so I did the governor arm adjustment as you described. I will double check tonight, maybe it’s the high and low that is incorrect. Question tho, does the governor shaft move very little? And with engine running and nothing connected to shaft. When I turn it, should the rpm go up and down?! Thanks for your help!!!
Shaft can move about 1/4 rotation, you will feel it bottom out...but don't try to do it by hand, move it forcefully so you are certain it has reached it limit of movement.

The Carburetor and Governor have to work in unison, so naturally are dependent upon one another (must both be connected). While on that subject...make SURE the throttle shaft and choke move freely in the Carb (not getting stuck) before you do anything else.

When you are certain you have the static adjustment right, then we'll move on to the low and high idle (engine speeds). Your low idle should be about 1500 rpm and your high idle 3600 (no load). Do you have a tachometer to check this with?
 
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TheBrad83

LawnSite Member
Location
Tuscola
Can I get a link to a service manual?! The one I got from my mower parts, the pictures are blurry and hard to read. Thanks
 
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TheBrad83

LawnSite Member
Location
Tuscola
That’s owners manual, I’m looking for service manual. Only found one link at my mowerparts. It’s blurry, Thanks
 

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