Tecumseh carburator problem

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  #1  
Old 05-12-11, 11:18 PM
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Tecumseh carburator problem

Hi, I've used this forum before, but usually I find other posts that cover my questions
and go from there. I like to find my own answers without bothering others too much.

However, this one has me stumped, I need help. So this is my first post.

I have an MTD Model 660 with a Tecumseh OHV130 206820b. The carburetor is 640065A as best I can tell, but is definitely a series 7, with the square bowl and wire bale
holding it on.

The mower sat outside abandoned over two winters. It wouldn't start, and after about
5 minutes of checking, I determined it was fuel delivery problem. I tore the carb down,
and the o ring on the main tube was goo. I found the part number of the rebuild kit,
730638, on the internet, then went to the mower shop looking for it. They didn't have
the whole kit, so the guy got me the essential parts, new needle and seat, new o ring
and a bowl gasket.

The kit includes these, as well as the bowl, bale, and emulsion tube. I just reused
the latter three, after soaking in cleaner, passing a 30ga (or whatever size that wire
that is in the middle if those twisty tie things is) through all the holes.

It starts right up, but after warm up and I start backing the choke off, it surges. If
I disconnect the fuel line at the carb, gas pours out in a steady stream, so It's not
vent cap, fuel filter, etc.

The Service manual shows another o ring in the main jet cavity, which I did not know
existed until I found the Service Manual. I want to put it in before I go further,
but have no idea what size it is, or the Tecumseh part number.

Does anyone know what size the main jet o ring is or the part number? I also need a
new gasket for the Bowl Drain Screw, so that part number would be helpful, but I can
always use some gasket material for that. The o ring is the basic question.

Sorry for being so long, Please help if you can. Thanks.
 
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Old 05-13-11, 07:38 AM
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o-ring 632547
gasket 27110A

AJ
 
  #3  
Old 05-13-11, 09:24 AM
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Just as a note, I think you can buy the whole bowl assembly for about $15, then you just snap it on and you are done. Have a good one. Geo
 
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Old 05-13-11, 06:39 PM
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Thanks for the help, that was fast.

With $10 and some labor invested already, $15 for the whole thing ready to go doesn't sound so bad. I'll remember that next time.

I used to lack confidence in Tecumseh, but they seem to be fairly rugged and reliable. I have a self-prop 22" with a TVS90 I bought in '94. Yes, it still runs great, and starts on the first pull. All I have put in it all these years is gas and oil, keeping a clean air filter and good plug helps, I'm sure.
 
  #5  
Old 05-13-11, 07:36 PM
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The problem with the old Tecumseh engines is/was that they built a false sense of security and people quit maintaining them, then when they fail the blame the engine. I have picked up mowers with a blown engine where it was obvious the oil had never been changes, interior of the block was oil crud paste, also those where the gas in the carb bowl sticks you fingers together like glue. Have a good one. Geo
 
  #6  
Old 05-13-11, 08:19 PM
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Here is a good link for series 7 carbs. Have a good one. Geo

Disassembly of Tecumseh Series 7 Carburetor
 
  #7  
Old 05-13-11, 08:50 PM
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Welcome to DIY mower99.

I was going to mention the little o-ring on the main jet while reading your description of the problem. I think that is the problem.
 
  #8  
Old 05-16-11, 05:22 PM
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Geo,

I had found that link previously and it is a good place for anyone looking at any Tecumseh carb, good info on many makes, B&S, Honda, Kawasaki, Kohler and Subaru/Robin. Plenty of pictures to look at, it was the picture that I looked at and said to myself, "Dang! There's supposed to be an o ring in there, too."

Cheese,

I took the o ring from the e-tube down to the hardware and found one the same size, 1/4"od x 1/8"id. Put it all back together, stuck the hardware store o ring in the main jet, and fired it up. Now it purrs like a kitten.

I hope this helps someone else.

Thanks to all.
 
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