Another Tecumseh Engine Problem

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  #1  
Old 12-19-08, 02:29 PM
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Unhappy Another Tecumseh Engine Problem

I could use some immediate help - as I can't get out of my driveway! I have a sear's Craftsman with a Tecumseh 4-cycle engine Model #LH318SA. For each year I've owned this piece of you knbow what, I have had nothing but problems. I'm sure some of it will be my fault, so let's just see what can be done. Yesterday I started it up in nice dry weather, and it ran OK. Coughed a little, and when it started up a puff of black smoke came out of the muffler, as it does each time it starts. Today I went to use it in the snow, and it reverted back to not wanting to start, even with the electric start - it rarely starts at all with the pull start. The gas and oil are fresh, and each of the last three years Sears has had to come out and either replace or clean out the carb. The machine is still under warranty, but it takes a month for Sears to come out which does me no good.

I feel the problem is the carb on this machine is prone to clogging, and although I am not all that mechanically inclined in terms of working on engines, I think I need to get dirty and give it a try as the machine does me no good if it won't run. When I do manage to let it sit and if it does start, it will run for a minute or two and shut down again.

If anyone has step by step instructions for carb removal and cleaning, especially if you have any photos to guide the process you would be a lifesaver.
 
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Old 12-19-08, 02:51 PM
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Half of the cleaning and year to year starting problems would be avoided/fixed by using Sea Foam in the gas and oil. It is the one additive I have found over a lot of years that actually shows a significant difference.

Start by putting in a new plug and getting some Sea Foam at Walmart or an auto parts store. Then .....

Pull the plug, spin the engine over about a dozen times with full throttle. Then add a teaspoon of new gas to the cylinder through the plug hole. Then half throttle, no choke, try to start. It should take off after a couple of tries if you have a good plug/spark. If the carb is completely blocked through the running circuit, the choke circuit will still keep it going until the Sea Foam can clean it out.
 
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Old 12-19-08, 03:16 PM
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Not sure I follow completely - you suggest picking up Sea Foam, but make no mention of where to use it. I watched the video on the Sea Foam site - am I adding it to the gas and oil on the snow thrower? If I am to add it to the carb throat as suggested in the video? If so, I'm back to my original question of how to access the carb on this machine - it does not seem user friendly to get to and I want to make sure I don;t screw something up or end up with gas spilling all over the place.

A little clarification for the mechanically challenged please.
 
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Old 12-19-08, 03:38 PM
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Some of the symptoms don't sound right, the black smoke would be too much gas and the engine would be flooding which could be a float level problem, anyway try the below and see what happens then post back as to your results.

Here is my normal post for Tec engines give it a try seems the bowl nut(main jet) usually is the problem.

Clamp off the fuel line, remove the carb bowl, release the clamp to see if you have good fuel flow to the carb, raise the float to see that it shuts off the flow with minimal pressure, clean the junk from the bowl, clean the bowl nut, 2 holes close to the bottom and a tiny one about midway up(I usually use the wire from a twist tie), spray all holes, cracks and crevases with brake parts cleaner, reassemble and you should be good to go. If this didn't work it will be probably be necessary to rebuild the carb. If I missed something one of the real mechanics will post to help further. Refer to the photo below. Have a good one . Geo
http://i190.photobucket.com/albums/z...c_bowl_nut.jpg
 
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Old 12-19-08, 04:07 PM
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Geogrubb,

Thanks for the tip - but perhaps you missed the mechanically challenged part. You lost me at clamp off the fuel line. I wouldn't even know where to start with that. At least removing the spark plug and adding fuel and Sea Foam was easy enough to handle.

Do I need to rest the machine on the front plate and stand it up to access the carb and the bowl? I tried taking the 2 screws off the side cover where the carb is and they don't budge - what type of screw tip or other tool do I need to remove this cover? Is marbobj off on his guesstimate? What if I tried that first - could it hurt to try it? I'm getting more confused!
 
  #6  
Old 12-19-08, 07:16 PM
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Let me unconfuse you. Most of the cleaning of the carbs has to do with fuel residue from fuel that has separated. Cleaners that dissolve that residue solve the problem. Some of those residues take some time for cleaners to get fuel past them because of the thickness of the residues. However, a good cleaner will often solve the problem.

You can clean the residues mechanically, as with a small brush or wire by dismantling the carburetor. Or you can remove the carburetor, dismantle it and soak it in a cleaner for a couple of hours, then blow it dry with compressed air or wash it with water, then blow dry. It depends on the cleaner.

Should you have a foreign solid, as in dirt in the carburetor, the only way to get rid of the dirt is to remove the bowl, empty it and reinstall it. If your filter is in place and serviceable, there should be no dirt in the carburetor. More often than not the problem is residue from fuel which is a type of varnish.

You can remove the carburetor and clean it. If you are mechanically challenged, and that is in no way a shortcoming - we all have things we do best, I would first use the Sea Foam additive. It will do the best job of cleaning a carburetor on the engine.

As far as instructions = those are on the can. Sea Foam can be used to clean engines and their components in a number of ways. Those instructions are all on the can and easy to follow.

I would suggest adding the Sea Foam to the gas and oil as well. Since you're dealing with a plugged carb put about three ounces to a gallon of the gas in the fuel tank of the snow thrower. Follow the instructions I gave you to get it started, using the choke to keep it running if necessary. Normally a partial choking of the carb is sufficient to circumvent the plugged circuit. This will allow the engine to draw the cleaner through the carburetor and work to clean it.
 
  #7  
Old 12-21-08, 04:38 PM
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Talking

I tried the Sea Foam remedy and it worked! I had 2 hours of uninterrupted blowing with no hesitation or problems.

I removed the spark plug, and put a small amount in the hole and replaced the spark plug. I poured another small amount into the oil, and about 1/4 or so of the can into the gas. Started it up and let it run for a few minutes in my case I had it at full choke and it started to die after about 30 seconds, so I went to about 1/2 choke. After about two minutes I took the choke off, and had no problems from that point on. Heck, I even was able to restart with the pull chain, and Ive never been able to do that before.

Thanks for the suggestions - it was great to have use of this machine without problems!
 
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