Tecumseh 16 HP only runs when choked.

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  #1  
Old 06-30-08, 10:16 PM
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Unhappy Tecumseh 16 HP only runs when choked.

I have an unknown year, used (as in history unknown) Huskee riding mower with a Tecumseh 16 HP. I know the mower has sat for a year with out running. The engine starts just fine and Idles nice and smooth. BUT it will not run at full throttle unless I leave the choke 50% enabled. If the choke is off and at full throttle, the angine misfires and backfires very loudly through the carb and exhaust. Also, what is the reason for the small solenoid under the fuel bowl?? what does that do?? What do you guys think I should check in reference to the back fire. here is what I have done so far. checked exhaust for obstructionand its ok. removed the carbed and cleaned it, put new fuel in and cleaned the plug. also I totaly removed the carb and sprayed starter fluid into the intake port and it ran the same way. I did the to rule out the carb. I have done this before to exclude the carb from the problem list on other engines. I think its the ignition, but its the unadjustable solid state ignition. please help
 
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Old 07-01-08, 10:58 PM
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It's the carburetor. It needs cleaning.
 
  #3  
Old 07-01-08, 11:07 PM
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Smile Thanks cheese!

Geez 40 views and only one response. Arent you all a wealth of knowledge. Cheese it seem like they are abusing you man. You know your stuff man, I have to hand it to you. How would you reccomend I clean it?? I removed it and sprayed it down real well. Any advice??
 
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Old 07-02-08, 06:35 AM
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I have little time to post. Just too busy this time of year. Assuming your engine is not an OHV engine the following may apply. Model number and DOM should be imprinted on your engine.

Your carburetor is an earlier fully adjustable carburetor that utilized a metering rod/pin in the drilled idle passage to "take up space". Instead of drilling the required small diameter hole Tecumseh drilled a larger hole and made it smaller by installing a metal pin to reduce hole diameter. This was a cheap way to do it with the consumer paying for their cheapness later. I have cut open carburetors and found the pin rusted and closing off the passage. These type carburetors can be shaken and if the passage and metering pin are in good condition, you can hear a rattle. The rattle is the pin moving. Also, if the metering pin is right inside the idle adjustment screw hole when the screw is replaced, damage to the adjustment screw tip is what usually results, or it can wedge the pin to where it will "stick" in that position. The condition I described above will cause surging.

Give you carburetor a shake and verify if this is your problem.
If you will look in the Tecumseh Technician’s Handbook for 3 - 11 HP 4-Cycle L-Head Engines Chapter 3 page 10 you will find an illustration showing a cross section view of the style carburetor you have. The illustration shows the “idle and intermediate fuel transfer passage” and the “metering rod or pin” in the passage.

Download this manual at this link to see the carburetor:
http://www.cpdonline.com/692509.pdf
 
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Old 07-02-08, 03:09 PM
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Kidding

Hey Airman, I was just messing around man. This is a great site......Ok, Its the Tecumseh ohv16, It has the "unadjustable" carb with the little weird solenoid under the fuel bowl. if this helps any. I did notice something strange. I hope I dont confuse you. I pulled the carb off. I flipped it upside down. I unscrewed the solenoid and removed the fuel bowl exposing the float. There is a long tube in the center that the solenoid screws in to to hold the bowl in place. well, I looked inside of it and i saw a much smaller tube running allong the inside of it, but is was not in the middle like I think it should be. I think its supposed to be in the middle. A tube with in a tube. Have I confused you?? The small tube inside seems bent to one side where the out side of the inner tube is touching the inside of the outer tube. Its not centered. Any ideas?
 
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Old 07-02-08, 06:29 PM
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Partially plugged jets require disassembly to remove the trash.
You can purchase a can of carburetor cleaner with a parts basket at most auto parts stores.
 
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Old 07-03-08, 01:07 AM
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The crooked tube inside the larger tube is normal...don't worry...it looks messed up, but it's what tecumseh calls normal. I suggest you go get a can or two of spray carb cleaner of the brand name "next dimension". This is available at advance auto parts. At my local store, they don't have it on the front shelf, I get it from the commercial counter in back, so you might have to ask for it. Don't let them convince you that they have a better brand, or even one as good. Then go to a welding supply store or lowes/whatever and get a set of torch tip cleaners. Then take the carb and work with it, spraying every hole and opening. Use the tip cleaners of the appropriate sizes to poke down every hole, especially those in the side of the bore of the carb right where the throttle plate closes against the inside. Also take the jet out of the top if there is one that is removeable, and clean it well and the carb area where it goes.

Be careful with this carb cleaner. It will hurt your eyes extremely bad for a short time if it gets there...like mace. It will also burn your skin. It works though.
 
  #8  
Old 07-09-08, 07:12 PM
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the small solenoid under the fuel bowl is the electric gas shut off valve. it helps when you have a leaky needle and seat, so you don't loose your expensive gas!
 
  #9  
Old 07-09-08, 11:01 PM
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The solenoid on the bottom is an anti-backfire solenoid, and doesn't help stop a leak caused by a bad needle, seat, or float. It shuts fuel off from the main jet into the venturi only, not into the bowl from the tank.
 
  #10  
Old 07-14-08, 06:03 PM
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Mine (OHV 17.5hp) only starts if choked -- even hot. Always has been this way. I settled for condition because I got it in exchange for one that would not keep running; dealer said it was something to do with the solenoid but his specialist could not fix it -- admitted I was the second buyer it had been foisted upon (it never ran long enough to get dirty).

I mention this because there seems to be mystery and magic surrounding the solenoid as the conflicting posts above (and my Tecumseh tractor #1) demonstrate. Does anybody really know what it is for and how it is controlled? Could it have anything to do with my weird hot start situation? Always starts, never floods until running on choke. Routine is crank, throttle to choke, starts, quick throttle adjust, go...

I joined to post this because it seems that the choke somehow bypasses the solenoid fuel supply which might then be energized by the running generator...
 
  #11  
Old 07-14-08, 07:12 PM
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The solenoid has nothing to do with any of that. It's not some complex device or anything like that. It is not bypassed by the choke, or have anything to do with hot or cold starting. It is a simple on and off switch. It completely stops all fuel flow through the carb to the engine when you turn the key off, and allows fuel to flow when you turn the key on. It stops this flow of fuel with a plunger that either is blocking the hole in the main jet, or it isn't. If the solenoid fails, it usually just shuts the fuel off no matter what you do. If you hear the solenoid clicking, it's working. The click is the movement of the plunger, so you rest assured that if you hear it click when you turn on the key, it is fine.

Hope that helps clear some of the mystery and majic .
 
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