# 2 cycle Tecumseh starts but will not continue to run



## plsbcheap (Aug 30, 2006)

I have a Tecumseh 4HP - 2 cycle engine (TVXL840) I have owned for 15 years. I love the engine for power and runs on any angle. I let it sit alot during the last year and now I can't keep it running. It will start after priming but will not keep running unless you pump "feverishly". That will keep it going but you can't increase the throttle. My guess is a carb rebuild but I have not atttempted that before. I have taken the carb a part and cleaned it good with carb cleaner but it still does the same thing when I assembled it back. Now I'm a little confused if I got the linkage back correct where it hooked to the governor.  BUT I don't think that has anything to do with the problem right now.

Any suggestions are appreciated. Since the carb doesn't appear to have a diaphram I don't know how the carb pumps fuel after priming has started the engine. I saw the "welch" plug when it was disassembled and scraped off the crud (varnish?) but are not sure what it does and how to know if it is bad.

Thanks for any help and advice.
:thumbsup:


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## big ed (Jul 29, 2006)

if thhis is a bowl type carb sounds like the main jet is clogged with the same stuff that was on the welch plug spray carb cleaner and compressed air is where id start but be careful the seat where the float needle sits may come flying out good luck


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## geogrubb (Jul 28, 2006)

I had a similar problem with the same motor it had a small piece of grass in the main jet(it's the bolt in the bottom of the bowl). When I first sprayed it with carb cleaner it only resulted in moving the grass out of sight the second time I made sure it was gone and so was the "priming to run" problem. Have a nice day. Geo


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## plsbcheap (Aug 30, 2006)

Geo and Big Ed,
You guys are awesome! Thanks for sharing you knowledge. I followed Big Ed's advice. Cleaned it good, blew it out, removed the seat and was about to reassemble when I saw Geo's comment. I did not notice that the bolt had holes in it and was functioning as part of the main jet. I sprayed it out (had never cleaned it before) and stuck a small wire through it. Sure enough he had some crud in there (probably varnish from stale gas). When I put it all back together I could tell when I pushed the primer that it was firmer and sucking better. It cranked on the first pull and ran very nice. I bought this engine new in the 80's and it has been fantastic until this leagering problem. As it turns out the stale gas clogged the jet. This was a great relief for me to get this off my to do list. Many, many thanks to you both. I hope someone can return the favor for me to you. :thumbsup:
Blessings,
Dwight


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## geogrubb (Jul 28, 2006)

plsbcheap;
Is your TVXL840 on a lawnmower, if so would you post what it is. The TVXL840 I am dealing with is on a 21" Lawnboy cast deck mower, I noticed the blade is really shot and I dont know what to replace it with it has a 5/8 hole and is 2 1/2" wide, the mounting bracket looks like a Lawnboy but my Lawnboys have a small bolt hole. Any ideas other than take the blade with me to the mower shop? Thank and have a nice daay. Geo


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## donv_1 (Sep 16, 2006)

I too have a similar problem with a 2-cycle Tecumseh...starts runs ragged (hunting) and then stalls...won't continue to run even on the choke ...yet hitting the prime bulb will occasionally help for a moment...the engine is on a Craftsman 3/20 single stage snowthrower Model #247884311, that was given to me (apparently the problem was frustrating it's previous owner)...I've found a parts diagram of the 'blower' only on the Sears Parts Site...No engine parts blow up diagram at that site...I've replaced the fuel/oil mix w/ fresh...no diff...bowl seems to remain full of fuel as engine stalls...still gas comming out of the spring loaded bowl drain when pushed in...I've not yet removed the bowl...I assume that the brass nut in the bottom of the center of the bowl holds the bowl to the carb throat cast...right?...I'm concerned that when I crack the bowl away from the housing that there will be a seal that I'll have to replace...readily available?...where do I find the proper setting for the adjusting screw in the center of the brass retaining nut...is this a liquid flow control or a float setting screw?...I dont see any air /mix adjusting screw...I'm assuming that the red plastic 3/8 inch thick disc about the size of a half dollar is a fuel filter...if it is , could it be clogged...or is it a flow check valve to prevent back flow...I guess I'm asking what is my next move??? and where can I get a parts diagram of the engine...HELP !

Thanks 
Don V


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## 30yearTech (Sep 14, 2006)

To donv_1 when searching the Sears parts site use the model number of your engine AH600-1664N and you should be able to pull up a parts IPL. If not email me and I can send you a "pdf" of the engine and carburetor. If you remove the float bowl from the carburetor body, you may or may not have to replace the O-Ring seal it just depends on the condition of the seal. The screw on the bottom of the bowl nut is the load or main jet adjustment for the carburetor and it is most likely plugged up with varnish or whatever.


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## 30yearTech (Sep 14, 2006)

To Geo, Sounds like your mower uses a Lawnboy Tri-Cut blade Lawnboy/Toro P/N 612543-03 also available after market, you can probably pick one up at Lowes or Home Depot if you don't have a Toro/Lawnboy dealer near you.


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## geogrubb (Jul 28, 2006)

30 yr;
Thanks a bunch;
donv;
Usually on the sears diagrams they will list a number for the engine (ie 54) then when you look at the parts list, part number 54 will say something like , engine xxx with the model number (ie, 143.65174), then enter that model number to find the diagram and parts list for the engine and some cases the engine diagram will have the same procedure for the carb and other assemblies. Have a nice day. Geo


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## donv_1 (Sep 16, 2006)

*Thanks and a Follow up RE: Gas Mix W/ Carb Cleaner*

30Year and GeoGrubb:

Thanks for the help...It's a busy time of year, sorry for the lag before acknowledgement...I guess that it's time to pull off the carb and clean it...I assume that a local small engine shop should have the 'o' or 'quad' rings that I may need...I assume that the bowl is held in place by the nut on the bottom of the bowl (the nut that has the main jet screw in it)...I probably cant make this snow thrower run any worse...so I'll get at it soon...is there any standard pre-set to the main jet screw on the bottom of the bowl when I replace it after cleaning...???...Like screw it all the way in and then back it out 1 1/4 turns...???...One more question (one of a lazy man or a man with little free time)...Would a carb cleaner fuel additive be effective at cleaning out the 'gum/gunk in the main jet area w/out damaging the engine...I suspect that a two cycle may be more sensitive to gas and oil diluting w/any type of solvent...???...Is it worth the gamble...???...If so any specific brand recommendation or specific % mix to be effective...???...I know that I'm looking for the easy way out...but I'm not in need of proving that I can remove, clean and replace the carb if I don't absolutely have to ...

Thanks Again Guys
Don Valley


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## geogrubb (Jul 28, 2006)

On engines that seem very carboned and have set for a long time i use a very strong mixture of Chevron Techronic. Need about 8oz of fuel and 1 of cleaner let it idle until the fuel is gone. Don't rev it or you will mess it up. You will be amazed at the stuff that start drippin out the muffler. Have a nice day. Geo


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## donv_1 (Sep 16, 2006)

*30 year and anyone else...same tecumseh start but no run...*

Well, I dropped the bowl cleaned the metering jet...checked the needlevalve to be sure there was no crap in it...reassembled it...same easy start -- but no run...then I pulled the plug and cleaned it, put a couple oz of carb cleaner directly in the gas mix and it started and ran a bit ragged but steady(didn't stall out)....interesting thing was that it only started and contimually ran when I started it w/ NO Choke...so weird...Could it be running only due to the carb cleaner in the mix...

Another observation, there is, what I'd like to consider, too 'little' smoke when running on the prescribed 32 to 1 fuel mixture...could it be that in it's previous life it was run on a mixture w/ too little oil and that it has somehow messed up the cylinder walls??? I've been told that if it was run on an incorrect mixture (too little oil) that subsequently the engine may start but then fail to run due to the cyl damage...

I tried a new plug (Champion CJ7Y) and it didn't stay running...Do I have the right plug???...so I put the original back in (could be that the new one wasn't gapped right)...I'll check it....028 ? ...I'm going to try it on the first small snow storm but I have my doubts as to it's ability to make a sustained run....another question...if a 2 cycle has in it's past been run on too little oil in it's fuel mix and has sustained a bit of cylinder damage will running a heavier mix, say 20 to 1 make a difference ???...(perhaps providing a better piston-ring/cyl seal)....I'm grasping at straws...hate to throw this thing out, but it's getting to that point...any last ideas???...bad coil???...bad wire???...run it on carb cleaner and dry gas concoction mix w/regular fuel???...run it on 'Jack Daniels' special mix???..

Junk It...

Thanks to all.....
Donv_1


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## 30yearTech (Sep 14, 2006)

Yes if it was run on a mix with insufficient oil mix then there could be damage to the cylinder, on this model engine it has a steel cylinder sleeve and unless the damage is severe it could be honed and it's possible that the rings may be stuck in the ring lands in the piston assembly. The spark plug you are using is correct. You might want to remove the muffler and inspect the exhaust ports for possible build up and while your there you can inspect the piston and cylinder. When damage occurs from insufficient lubrication the most damage occurs on the exhaust side of the piston so any damage will show up here. Also you can check the rings to see if they are stuck by pushing on them with a small screw driver, they should push in slightly and spring back out freely. You can try mixing some sea foam in with your fuel to clean out the carbon build up or the stuff geo suggested.


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