The Tecumseh engine on your snowblower may need to run on "Full" choke temporarily under certain conditions, but if you have to leave it in full choke to operate the machine sustainably, something is not right. Troubleshoot. You'll need to consider cold starting, needle-valve air-intake adjustments and carburetor cleaning. Troubleshooting might get you back blowing snow even if you have no experience working on a Tecumseh engine.
Cold Start and Sputtering
Consider the conditions under which you are attempting to start the 5-horsepower Tecumseh engine. A "cold start" occurs when the engine is completely cold and has not been used recently. Additionally, temperatures outside can increase this effect. It's recommended to always adjust the throttle to full choke when starting a Tecumseh engine completely cold. Ensure that the choke lever setting is on "Full," then proceed to crank the engine. Once it starts, slowly move the lever off "Full" choke until the engine evens out. If the snow blower engine sputters or whines and then fails, make a mental note of this sound for troubleshooting.
Needle Valve Adjustment
Find the carburetor, located halfway up the left side of the engine. It is distinctive because of the immediately recognizable bowl shape. Locate the slender needle valve near the bottom of the carburetor bowl. This adjusts air intake into the engine and could be the reason for the sputtering and winding out of the engine following the cold start. Turn the needle valve all the way to the right, then get the Tecumseh engine running on choke. Back slightly off the choke, just enough to get the engine sputtering and whining again. While listening to this noise, turn the needle valve back to the left a quarter turn. Listen to any change to the engine's sputtering. If it continues, continue making gradual quarter turns, to the left, to the needle valve until the engine smooths out. These valve adjustments may prove enough to get the engine running without failing even when the choke lever is backed entirely off "Full."
Carburetor Bowl Cleaning
Begin to disassemble the carburetor bowl for cleaning if the Tecumseh engine still won't properly run off choke even after persistent needle valve adjustments. Ensure the engine is off, then place a dish under the bottom of the carburetor bowl. Remove the nut on the bowl's underside using a socket wrench. Wait as excess fluid drains from the Tecumseh engine into your dish. After this process finishes, screw off the carburetor bowl with your hands and clean its inside out with a cloth and a carburetor cleaning solution. Scrub the bowl's removed nut with a wire brush and the cleaning solution.
Carburetor Reassembly and Final Adjustments
Screw the Tecumseh engine's carburetor bowl back onto the engine, then tighten its removed nut into the underside of the bowl with clockwise turns from your socket wrench. Your engine will now run efficiently, although upon starting the engine you may need to tweak the position of the needle valve again now that the carburetor has been cleaned. Alter the needle valve slightly just as you did before while listening for engine sputtering. Continue with adjustments until all sputtering and whining ceases and the engine runs smoothly without relying on the choke.