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Governor adjustment on Tecumseh HM100


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12-28-10, 07:00 PM   #1  
Governor adjustment on Tecumseh HM100

I made a big mistake while trying to check the integrity of the prime bulb to carb hose on my Ariens snowblower and removed the arm that connects the throttle and speed control linkages to the governor. I ruined the linkages and speed control, all of which have been replaced. The engine is a Tecumseh HM100-159119N.

I have downloaded the Tecumseh service manual and am confused by the section dealing with the governor adjustment, specifically the relative position of the arm in relation to the governor clamp. The manual states

"Rotate the clamp in a direction that will force the throttle shaft open and allow the governor follower arm to rest on the governor spool."

Can someone explain what this means? Should the gonvernor clamp be rotated CW or CCW to its extent, then tighten the screw?

I'll post a pic of what it looks like (NOTE: the arm is upside down in this picture, and has since been corrected)


 
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12-29-10, 07:35 AM   #2  
"With the engine stopped, loosen the screw holding the governor clamp on the governor lever. Rotate the clamp in a direction that will force the throttle shaft open and allow the governor follower arm to rest on the governor spool. Push the governor lever connected to the throttle to the wide open throttle position. Hold the lever and clamp in this position while tightening the screw (diag. 7)."
Not being there but after reading above, I'd loosen the clamp at the governor shaft, push the flat arm whichever way makes the throttle wide open and then tighten the governor shaft clamp.

 
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12-29-10, 07:51 AM   #3  
Thanks for the reply. The problem with those instructions is that when the screw that the arrow points at in the picture is loosened, the governor clamp and arm can rotate independently of each other. The arm could be be rotated to keep the throttle open, but the clamp can be rotated independently to either extent (which is only about 10 degrees of rotation) without changing the position of the arm. That's where I get lost.

 
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12-29-10, 08:58 AM   #4  
It can only be one of two ways, I can't tell from the pic which way the arm needs to move to open the throttle to full so....
Try moving the arm to open the throttle to full, then turn the shaft full opposite and tighten set screw.
Try it and be ready to shut down if it tries to run away or won't start, then try the opposite on the shaft.....


Just needs a bigger hammer
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12-30-10, 11:33 AM   #5  
OK, I tried several positions, starting at the CW extent, then working CCW. At CW extent, the engine ran too fast even with the RPM adjustment screw on the speed control all the way out. At the half way point, it would run very slowly and die when the impeller was engaged, even with the RPM adjustment screw on the speed control all the way in. The best location seemed to be just short of the CW extent, but even at this location the engine tended to hunt periodically when idling at full speed even after adjusting the carb and RPM adjustment screw. There's not enough snow to test it any further.

 
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12-30-10, 01:25 PM   #6  
Are you holding the arm and the shaft to the full extent of each? IE: Move the shaft so the throttle valve opens fully and hold it there, then turn the shaft full stop then tighten?

Starting to sound like a carb problem...


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02-19-11, 01:34 PM   #7  
Would anyone be kind enough to spell this governor adjustment out for me in simple terms? I just replaced the carb on the HM100 on my Snapper snow blower. In doing so I loosened the same screw pictured above by DIYNovice. Now when it starts up the engine wants to run really fast. I am pretty sure all the linkage is correct and it is a brand new oem carb so it must be this screw. Also anyone know where to download the service manual DIYNovice mentions above? Thanks in advance, Mike

 
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02-19-11, 03:51 PM   #8  
Here is the link to the service manual: http://www.cpdonline.com/692509.pdf

I had to use trial and error to get mine correct. I started with the governor all the way to its clock wise extent (when looking at the picture I posted), held the carb arm full open, and tightened the screw. This made it race, even with the screw on the speed control (where the other linkage connects to) all the way out. I loosened the pictured screw and moved the governor slightly counter clockwise (being sure to keep the carb arm full open) and tried again. From that point I was able to make final adjustments with the speed control screw and a tachometer. Running RPM should be 3600.

 
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02-20-11, 01:01 PM   #9  
Thanks for the tips and the link to the service manual. After a lot of expirmenting I found the only way to keep it running smooth at high speed is to adjust the governor fairly tight. Otherwise it hunts. Almost seems like a bad governor. Anyone know if it is easy to change?
I still have some other problems. It won't idle below 1/2 speed. It sure seems like a carb problem but it's a brand new oem carb and the one before it had similiar problems. Anyone have any suggestions? Gas is good and it has a new plug.

 
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02-20-11, 03:11 PM   #10  
Maybe your speed control assembly is shot. I forgot to mention that I replaced mine too during this process and could notice a big difference between the old rusty one and the new one. My part number was TEC 34677 (google it), not sure if it would apply to your engine.

 
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02-20-11, 04:33 PM   #11  
I googled it and it looks like it's the same as mine. I will do a close inspection of mine tomorrow. How did you know yours was bad?

 
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02-21-11, 06:18 AM   #12  
Mine looked somewhat rusty (it was an original part, about 25 years old) and the spring didn't seem to respond very well, possibly because I distorted it while removing and installing the linkage. This was only confirmed when I compared it with the new one.

 
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02-21-11, 08:51 AM   #13  
Looks like we have the same engine except mine is on a 25 year old Snapper instead of an Ariens. I didn't distort any of my linkage or spring but the spring is rusted and seems weak. Linkage is a little rusted to. I think I will order the assembly and the 2 linkage pieces just to have everything new. Thanks, again.

 
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