# Tecumseh Carb problem



## hotrod_magee (Oct 30, 2007)

I'm working on a newer Ranch King snowblower with an 8hp Tecumseh (HMSK85 155905B). The problem I am having is surging at high rpm and unable to idle at low rpm. I am assuming the major cause is the lack fuel at idle is messing up the high end. So far I have cleaned the carb (including removing the plastic tube, welch plugs, etc. and dunking it in carb cleaner the second time), putting a carb kit in it, and doing a valve job. I'm at a loss as to what to do to get this thing to idle. Any help would be great.


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## pyro_maniac69 (Aug 12, 2007)

is it irradic surging? or just every once in awhile is burps?

if it just burps every once in awhile you probably won't be able to do anything since the EPA mandates these carbs sun so lean.

another thing you can quickly try it start it, take some window cleaner and spray it around the motor, see if any bubbles appear


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## justin3 (Apr 10, 2007)

Sometimes those tecumseh carbs are just not repairable, I have rebuild the carb on my parents snowblower about 3 times, this year it was surging again so I ended up just replacing the carb for $70 now it runs better. Your problem would only be valve related if you noticed the carb spiting out fuel. Other things to check would be the coil gap, and flywheel key.


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## 30yearTech (Sep 14, 2006)

Possibly a plugged pilot jet. There is a plastic cap on the side of the carburetor, pry it out and underneath is the pilot jet. Unscrew the pilot jet and make sure it is clean and the orifices are open, make sure the passage leading up to the jet from the bottom where the main jet screws in is clean. 

Justin, you can have valve problems that can affect the way the engine runs without having fuel spit back through the carburetor, but generally they will not cause an engine to surge.


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## hotrod_magee (Oct 30, 2007)

Right now the engine surges. Its a rythmic surge that is lessoned to almost gone with the choke at 1/2 to 3/4 on. It will run for a little bit after you open the choke all way (off), then goes back to surging. 

I just did the valves because at one point it was running decent, with just an occasional miss and it appeared the exhaust valve was burnt, causing the muffler to glow cherry red. 

Maybe I am wrong, but I keep thinking it shouldn't need a new carb. I've cleaned many before and didn't have to replace them. I'll check the coil gap and other suggestions. I've had the pilot jet out and it appears to be fine (and have cleaned it too). Also I have drained the old fuel out with no luck there either. Thanks for the help.


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## 30yearTech (Sep 14, 2006)

Unless there is corrosion or pitting in the carburetor replacement should not be necessary. Surging usually involves the low speed circuit, you need to make sure the low speed fuel pick up to the pilot jet are open by spraying cleaner through them, make sure the pilot jet is clear and that the low speed jets under the welch plug are clear as well as the passage from the pilot jet to the welch plug.

Good Luck...


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## hotrod_magee (Oct 30, 2007)

I just got done stripping the carb down again. It doesn't look pitted at all. So its getting dunked for about 4hrs (while I'm at work), then I will go thru everything idle related and make sure the passages are open. Thanks for the help. I'll let you know how it turns out.


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## hotrod_magee (Oct 30, 2007)

OK, this time it is actually running the way it should. I'm not sure what exactly I did, but all passages were cleaned and the carb is working properly. Thanks for listening to me vent/helping me out.


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## 30yearTech (Sep 14, 2006)

hotrod_magee said:


> OK, this time it is actually running the way it should. I'm not sure what exactly I did, but all passages were cleaned and the carb is working properly. Thanks for listening to me vent/helping me out.


You got whatever was obstructing the idle circuit out, thats what you did!

Good to hear it's running properly....


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