Tecumseh 3 HP engine (h30-35387s) running rich

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  #1  
Old 03-18-11, 11:39 AM
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Tecumseh 3 HP engine (h30-35387s) running rich

I have a Troy-Bilt Tuffy rototiller with a Tecumseh 3 hp engine that I bought used. The carburetor was very clogged; I cleaned it and tried to run it. The spring clip for the needle valve was missing.

The engine would run okay for a few seconds, then die. I believe the problem was the needle valve was not opening up fast enough to let fuel to the carburetor bowl, so it would use up the fuel in the bowl, then die. I bought a rebuild kit & replaced the needle valve, seat, gasket, and both adjustment screws (& o-rings). When I started it, it would run, but was running rich (I took off the air filter, and it ran a little better; I also blew air into the carburetor, and it ran great).

I adjusted both adjustment screws all the way in, which produced the best performance, but still very poor; this was after trying to adjust them out, which caused the engine to bog down & die. I talked to someone at the parts desk, who suggested I may have installed the needle valve seat upside down, so I reversed it. It is still running rich. I could wedge something to hold the throttle (open?) and it would run fairly well, but still not right.

It appears to have good compression & spark, because it would run well for a few seconds before I rebuilt the carburetor. Do you have some ideas of what the problem could be? Thank you for your help.
 
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  #2  
Old 03-18-11, 04:06 PM
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I think this is the manual for your engine. Have a good one. Geo

http://www.cpdonline.com/692509.pdf
 
  #3  
Old 03-18-11, 06:44 PM
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Sure sounds like you have a carb problem still. Did you get the seat in the correct way? Is the float full of gas? Shake it near your ear and listen for sloshing. If it is, replace it.
 
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Old 03-19-11, 09:39 AM
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Thank you for the manual & ideas about the carburetor. I had the seat installed correctly at first, then changed it (per the parts desk suggestion), and have since changed it back (the manual showed the proper way to install it). The float does not have liquid in it, but it does appear to be VERY sensitive regarding the position (angle).

I have tried bending the tab where the clip (that holds the needle valve) attaches, and have gotten to run a little better, but it goes from running rich at one angle, to dying after a few seconds with what seems to be a minor adjustment. I wouldn't think the proper operation would depend upon such a tiny change in float angle. Is there something else that could cause this?

The hole in the new seat is larger than the old one, and the new seat is thinner than the old one. Therefore it seems that the angle did need to be adjusted a little, plus with a larger diameter hole, gas enters the bowl more quickly ...

I tried adjusting the screw on the throttle lever to make it run faster, and was able to get it to run fairly well for a minute or two, but when I tried to engage the tines, it died in a few seconds.

I put a new spark plug, fuel line, & air filter on it. I replaced both Welch plugs & cleaned all the little holes behind them.

Thank you for your help.
 
  #5  
Old 03-25-11, 07:39 PM
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I took the carburetor off of a 4.5 hp Briggs & Stratton lawnmower engine, put it on the Tecumseh engine on the tiller, and now it runs great.

Thank you for your help.
 
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