Tecumseh HSK70 Carb Problem

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  #1  
Old 01-11-11, 06:27 AM
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Tecumseh HSK70 Carb Problem

Since one of my pet peeves is people that hijack other people's threads, I'll start (yet another) Tecumseh carb thread.

HSK-70, carb #640082 (older type I, non-adjustable)

Probably easiest if I lay out the sequence of events:

Has run terribly for last several years, hunts like crazy, sputters, and leaked gas pretty bad. I was just too lazy to do anything about it till this year.

12/20 - Tore it apart, thinking I would do a rebuild. Unfortunately, I'm an idiot and bought the wrong rebuild kit (31840 - is actually for an adjustable carb - rats!) - Some of the 31840 parts and O-rings are the same, so I replaced what I could, cleaned out all of the orifices/passageways (including both holes in the bowl nut), cleaned it till it was shiny, and reassembled it. (NOTE: float is fine, and I did not change welch plugs). Mixed generous amount of Seafoam in tank to get rid of any residual varnish.

Yahoo! Runs like brand new...strong, no sputters, no leaks...perfect.

12/26 Blizzard (upstate NY) Ran it for over an hour. Still running like a Swiss watch - blasted through 2' drifts like a hot knife through butter. Broke my arm patting myself on the back.

1/6 Snowstorm - Ran great for about 30 mins...then sputtered and died. 4-5 pulls and full choke to restart. Runs OK for 90 seconds on 3/4 choke...sputters once...dies. Finished with shovel. Too aggravated to think about it till last night.

Last night - Removed bowl nut and bowl. Cleaned both holes in bowl nut. Sprayed carb cleaner all over carb. Cleaned and inspected as best I could...all looks fine. Reassembled.

Starts on full choke, runs for 90-100 seconds on 3/4 choke...sputters once...dies (similar to 1/6). Restarts on 1st pull (full choke, no priming) and will runs again for 90-100 seconds on 3/4 choke...sputters once...dies. Almost seems like it's burning the fuel in the line, then starving...hmmmm.

Drained tank, pushed small phillips head screwdriver up though hole (thinking it may be clogged) - possibly felt some cruddy resistance but not sure. Anyway, it's clear now. Fuel line is clear and fine. Reassembled. (NOTE: as far as I can tell, this is a non-venting cap)

Same as before - runs (fairly strong) for 90-100 seconds on 3/4 choke...sputters once...dies.

Contemplating another rebuild with the correct kit (632760), but may just replace the whole carb.

Your thoughts?
 
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  #2  
Old 01-11-11, 10:23 AM
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Update:

Rebuild kit 632760B $19.29 available locally.

New carb:640082 - local shop says it's no longer available. They recommend contacting TEC and asking if there's a replacement, and what parts may need to be swapped over from old to new (ex. choke shaft, etc).

Any of you TEC experts have any ideas?
 
  #3  
Old 01-11-11, 11:10 AM
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When I rebuild a carb, I soak it and the main jet overnight in a carb cleaning solution avaiable at your local auto parts store. Then, rinse in water and blow out ALL holes with compressed air.
 
  #4  
Old 01-11-11, 11:54 AM
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Just curious...as I mentioned, in my first sort-of rebuild - I didn't change out the welch plugs. I know there's some sort of jet(s) under the welch plugs...should I re-do it and make an effort to get those out?
 
  #5  
Old 01-11-11, 01:14 PM
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I dont remove the welch plugs. By soaking the carb overnite, the cleaning solution gets into & cleans the holes under the welch plug.
 
  #6  
Old 01-11-11, 04:22 PM
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I know you stated you cleaned both holes in the bowl nut(main jet), however depending on different peoples views there might be 2 to 4 holes, anyway, the one that is usually the problem is the tiny one near the top, there are several designs for the bowl nut so use the pic below for reference only, on some it is almost invisible, I use the wire from a twist tie to clean it. Have a good one. Geo

 
  #7  
Old 01-12-11, 06:13 AM
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Thanx geo - yup...got that teeny tiny hole too (also used twist tie!).

I found the OEM carb 640082 at a couple of places on line - and ordered one from needlawnmowerparts.com - I've never ordered anything from them. I have my doubts that they actually have it - expecting an email saying "We are unable to fill your order..." - we'll see.
 
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