# Problem



## airhog (Oct 14, 2008)

I have a tecumseh HS40 engine that hunts at all rpm's low or high. I have removed the carb and cleaned it, removed all needles for cleaning, checked the float for leaking(seems ok), adjusted the float level with a 11/64 drill bit, used a base setting of 1.5 turns for the high speed needle and 1 turn for the low speed. Adjusted the engine while running at high speed and low. After this it still wants to hunt at all speeds.
What should I do next. Does it need a carb kit? Do I need to adjust the governor linkage. Any help is appreciated.

Do not know what my next step should be.


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## paulr44 (Oct 14, 2008)

There are several reasons an engine can hunt. Cleaning the carb. may actually make it worse sometimes, as the throttle shaft may have had some gum or a foam washer sealing it and now it's allowing a vacuum leak. I would suggest you do the following: First, run the engine and hold the throttle (plate on top) open just a bit off idle. If the engine stops the surging, then it's probably not the carb. Given an HS40 age, I'd check the carb. though too - turn it off, and check the throttle shaft for play (wiggle), at near WOT (wide open throttle). If it wiggles about 0.010" or more, time for a new carb. If good, check which hole the governor spring is in. If it hasn't been moved, it usually sits in about the middle hole, or just below middle on Tec. engines. Moving it definitely affects governor response. Moving it toward the governor shaft makes it faster to respond, but with less tension it can hunt more. Moving it away from the shaft lessens sensitivity. There's also governor droop, but forget that for now. Yes, I would reset governor free play. In such situations, I usually set it a bit off from the correct setting. The correct setting is zero play. To zero it, have the engine shut off. Move the control to full throttle to open the carb. up to WOT. Loosen the governor arm clamping screw. With blunt pliers, twist the gov. shaft left to right to make sure you have it free - the arm should not move. Now twist the shaft in the same direction of full throttle - in other words, the same direction the spring is pulling the arm. Hold the shaft there, with no real pressure on it but keep it from moving and tighten the clamping screw. TaDa! That the way to set ALL centrifugal governors. My "off" setting for sensitive ones, is to back the shaft "away" from zero a tad. That often relieves some of the sensitivity. Finally, the governor internally could be sticky, due to a groove worn in a component. The HS40 engines have a shaft that bends and kind of looks like a record player tone arm, which rides on a phenolic spool. Tecumseh spools sometimes get a groove in them, either over time from dirty oil or from overheating. Mixture too, can affect hunting.


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## 30yearTech (Sep 14, 2006)

airhog said:


> I have a tecumseh HS40 engine that hunts at all rpm's low or high. I have removed the carb and cleaned it, removed all needles for cleaning, checked the float for leaking(seems ok), adjusted the float level with a 11/64 drill bit, used a base setting of 1.5 turns for the high speed needle and 1 turn for the low speed. Adjusted the engine while running at high speed and low. After this it still wants to hunt at all speeds.
> What should I do next. Does it need a carb kit? Do I need to adjust the governor linkage. Any help is appreciated.
> 
> Do not know what my next step should be.


Since the engine wants to hunt at all speeds, I would suggest doing the static governor adjustment, although I would forgo the "tad" adjustment described in the previous post. All internal governors to operate correctly need to have no play in them or they will either hunt or over speed. I don't care what anyone tells you. If the governor does not operate correctly when properly adjusted, there are other issues that need to be addressed.

You can find links to download a service manual for your engine in the sticky post thread in the 4-cycle engine section that will provide detailed static governor adjustment procedures.

Best of Luck...


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## airhog (Oct 14, 2008)

This is great information as I needed a process to follow and to know how these systems are related to each other on the engine. It makes sense now, it’s amazing how something can be made easily understandable.
I will be trying this out over the next couple days and will keep you posted. Thanks for the help!


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## airhog (Oct 14, 2008)

I have zeroed the governor shaft to make sure it is corect and then I moved the spring from a setting 4 holes from the top to the top hole. I started the engine, let it warm up and then held the throttle in a position just past idle to see if the engine would hunt without the input from the governor and it runs steady. I then ran the engine this time without holding the throttle linkage and the engine would still hunt a lower RPM's but is almost gone a high RPM's. Moving the spring to the upper hole has helped. While the hunting is reduced at lower RPM's it is still present.
Although I did take the carb off before I did not specifically check any passages or holes in the main jet tube as I was not aware any were present. I will check this next to make sure they are clean.


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## paulr44 (Oct 14, 2008)

airhog said:


> I have zeroed the governor shaft to make sure it is corect and then I moved the spring from a setting 4 holes from the top to the top hole. I started the engine, let it warm up and then held the throttle in a position just past idle to see if the engine would hunt without the input from the governor and it runs steady. I then ran the engine this time without holding the throttle linkage and the engine would still hunt a lower RPM's but is almost gone a high RPM's. Moving the spring to the upper hole has helped. While the hunting is reduced at lower RPM's it is still present.
> Although I did take the carb off before I did not specifically check any passages or holes in the main jet tube as I was not aware any were present. I will check this next to make sure they are clean.


Sounds like a worn throttle shaft. What's the engine on?


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## airhog (Oct 14, 2008)

paulr44 said:


> Sounds like a worn throttle shaft. What's the engine on?


The engine is on a snowblower


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## paulr44 (Oct 14, 2008)

If where you are it isn't very cold out yet, and if it only surges when warmed up, it's because they're designed to run properly in cold weather and it's overheating the intake air and carburetor. If you have the heater box off, it should run reasonably well in any climate. Idle surging without high-speed surging is usually a sign of a carb. problem. The idle circuit may be restricted, and when the engine starts to stall the throttle opens up a little exposing the progression circuit holes (mid-range circuit) reviving the engine, which then returns to idle when the governor pushes the carb. back down, and the cycle repeats, creating the surge.


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## airhog (Oct 14, 2008)

Good News! 

The engine is running like a champ. I removed the high speed needle and tube and cleaned out the two passages in the tube. I also replaced the rubber O ring on the high speed needle as it was deformed and cracked. After a quick prime and a pull the engine sang like a champ at all RPM levels. Under load the governor worked perfect.

Thanks for all your help.


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