Surging

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  #1  
Old 11-15-04, 11:09 AM
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Surging

I have a tecumseh 9 HP engine thats surges and backfires. New gas, remove nut on bottom of cab. bowl and cleaned out holes but it did not help. The engine is only about 3 years old.
 
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  #2  
Old 11-15-04, 05:26 PM
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If this engine is 3 years old, it may possibly need a better cleaning than that. Make sure you are at least using automotive Gumout Spray and compressed air to clean out every orphis of the carb. If you are still having trouble, than you may need to adjust your high speed mixture screw. Let us know how it goes
 
  #3  
Old 11-15-04, 05:49 PM
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Thanks for the input.
Can you tell me where the high speed adjust screw is located? Do I have to remove the cab. to do this cleaning?
 
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Old 11-15-04, 06:43 PM
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bill
the high speed screw is located on the bottom of the float bowl. It will look like a brass colored nut with a screw going through the center of it. Turning it counter clockwise will richen the mixture and clockwise will lean it out. Here is a site that you can download a great manual for Tecumseh engines and it has a terrific step by step on rebuilding of the carb. http://www.cpdonline.com/692509.pdf
Yes you will have to remove the carb to do a thorough cleaning but just to adjust the high speed screw, you can leave it on.
Hope this helps.

snoman
 
  #5  
Old 11-15-04, 07:00 PM
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Thanks again for the info.
I looked for that screw on the bottom of the Cab. but only found a nut but it did not have a screw in it. The nut is called a High speed bowl nut.When I removed this nut it did have 3 holes it two on the bottom and a smaller one more to the top, that is what I cleaned. There is also a screw that's called the idle mixture screw ( just above the bowl) and when the engine is running this screw turns by it self.There is no spring like other adjustment screws to hold it in place? This is a Sears Model number 143.029003.
 
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Old 11-15-04, 11:24 PM
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I'm not sure if that one had a spring or not. If there's room for one, then there probably was.
 
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Old 11-16-04, 10:55 AM
Azis
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Check the manual snoman posted and go here and enter your model # to find a parts breakdown http://www3.sears.com/.
I am pretty sure there is supposed to be a spring on your idle adjustment.
 
  #8  
Old 11-17-04, 05:46 AM
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That web site had very good info, thanks.
I have learned a lot about this carb. in the past few days with your help. I need just one more bit of info. How do you remove the main nozzle tube from the carb.? The carb. number is 640052.

I was also reading about shaking the carb. and listen for rattle sound from someting called the emolltion tube. If no rattle is heared ( holding all other parts from making sound) then the carb. needs to be replaced?

O.K, that's was two bits of needed info !!!
 
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Old 11-17-04, 10:23 AM
Azis
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Well Bill that is the first I have heard of that but great find, I did a little diggin and found this http://www.jackssmallengines.com/faqrebuildcarb.cfm which pretty much states the same thing as you in reference to the emulsion tube. Sure sounds like ya need a new one. I may have to do some readin in my manuals now just fer me own peace
Last I checked the base carb was around 60 bucks, the link above is for jackssmallengines, it looks like a nicely written instruction for rebuilding Tecumseh carbs. Jacks does however sell most parts you would need, so if ya find the instructions helpfull in anyway maybe at least check out their prices.
Think I will see if we can get a moderator to do some actuall moderatin round here LOL and add some of these links to the FAQ or sticky or whatever.

GL bill and keep us posted

P.S. Thats why I love this forum, I know now what I knew not yesterday
 
  #10  
Old 11-17-04, 11:19 PM
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You don't think I'm moderatin' enuff??

Because of forum policy, I can't and wont make that a link in the FAQ/stickies. It is a commercial site, which is not supposed to be linked to at all in these forums...even in this thread. I am leaving it, however, because it is helping this member solve the problem they are having. I don't know if that's acceptable to the administration or not, and will find out. I like to see members get help around here...so I don't think it'll be a problem. (the link isn't directly to the commercial portion of the site).
 
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Old 11-18-04, 09:24 AM
Azis
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Hehehehehe...I must a rattled a cage or 2 maybe just the word Moder..... throws a flag somewhere LOL, could swear after that post at least 2 of em showed up somewhere...
I hadnt thought of the comercialism thing but yep guess rules is rules, I had only noticed a nicely written tutorial
U da cats pajamas Cheese u do the best modratin of all modratin I seen
 
  #12  
Old 11-18-04, 09:52 AM
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Ok you two, remember you are here to help the one's with problems not create them !!!!!!! LOL

Well I cleaned and installed the carb. and it help with the surge problem the only problem is every once in a while the engine seems to misfire (backfire). It happends more at high speed then low speed. It runs well when not doing this. Any ideas?
 
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Old 11-18-04, 10:10 AM
Azis
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LOL Bill, Problems were too few gotta quota to keep :P
Did you happen to check your emulsion tube?
The manual snoman posted http://www.cpdonline.com/692509.pdf should have your exact carb mentioned with a section on adjustment. Sometimes a mixture adjustment can cause backfire. In the manual is also a troubleshooting section, it should list the symptoms and possible remedies. You may find some causes not related to fuel or carb, although since we have been directing your efforts towards the carb, check those first.
If you dont find anything come on back, we may have a battleroyal goin by then.
 
  #14  
Old 11-19-04, 01:40 AM
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No problems here!! Just friendly ribbing. You didn't rattle my cage Azis, and apologize if I made you think you did. I wouldn't run off a super member like you, who helps so much on the boards.

I checked with the "higher - ups" and they said the link will be ok. So feel free to use it!

I also agree that the mixture adjustment screw may be the cause of the backfiring. It sounds like the engine may be running just a bit lean. You might have to go back and clean out the tiny holes in the bowl screw if adjustments don't help.
 
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Old 11-19-04, 02:29 PM
Azis
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Never a doubt here Cheese, although only a few months I been hangin round here, but I think we get one another

Oh thx fer the quick n fancy moderatin there too
 
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Old 11-19-04, 04:28 PM
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So, how is it going, update?
 
  #17  
Old 11-24-04, 06:45 AM
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Update, I replaced the mixture screw ( non adjusting type), everything is back together. Engine starts right up but still misses every once and awhile. I may just leave it at that and see how it performs under load, first snow storm. I live in New England so I should be testing it soon.
If anyone has any other ideas I'm open to them.

Thanks again for the help.

Bill
 
  #18  
Old 11-24-04, 10:43 AM
Azis
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One thing I just worked on a mower that was surging, it had the carb rebuilt by a shop but was removed and installed by the owner. It would surge at full throttle. Once I got the linkage and mixture returned somewhere to normal it still had the same sypmtom. While removing the carb I noted the gaskets between the carb and intake, one of which had not been installed properly and missed one of the bolt holes. It was an obvious air leak, installed correctly and voila out the door.
You may want to check for leaks as well, usually you can take a can of carb cleaner or WD40 and with the engine running hit each gasket joint with a blast. If there is a leak it will suck in the spray and should cause a noticeable RPM change. Any leak even small ones will effect carburation and since air is induced after the carb, mixture adjustments will be difficult if not impossible.
 
  #19  
Old 11-24-04, 03:24 PM
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Thanks for pointing this out. I, too, have an engine (3hp Tecumseh 2-cycle) that surges or throbs. I'll test for an air leak tomorrow. Thanks.
 
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