# Troy Built wont run without choke



## David R (Jun 15, 2008)

just got this trimmer (TB25CS) ... looked hardly used, starts right up but wont keep running without the choke ... I had to use tape to keep the choke on so it would stay running .... I dont know much about 2 cycle engines ( i thought the float was stuck, but there is no float or bowl that I am used to seeing) can anyone help me get this fixed?


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## geogrubb (Jul 28, 2006)

There are several things that go wrong with 2-cycle trimmers, usually it's bad fuel lines, dirty carb/diaphram and air leaks, so I suggest starting with the fuel lines. Have a good one. Geo


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## David R (Jun 15, 2008)

Thanks for the reply ... I did find that the fuel line was broken, inside the tank ... i replaced it, now it wont stay running, choked or not ... I guess a carb rebuild is in order ... I also noticed that the primer bulb wont fill and it collapses when pumped, and takes awhile to "pop out" ... not much fuel in there when it does


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## geogrubb (Jul 28, 2006)

Usually when the fuel line breaks inside the tank it picks up some junk and contaminates the carb, etc. so my suggestion is to replace all fuel lines, remove and clean the carb by blowing through all holes, cracks and crevases with brake parts cleaner(it doesn't leave residue). Then install a new diaphram kit, if the new kit comes with a new metering arm, use the old one unless it is very worn, you might as well install a new primer bulb since they usuall fail along with the fuel lines, put it all back together and you should be good to go. Make diagrams for fuel lines, if it has adjustable High/Low jet screws, screw them to seat counting the turns so you can reset them after cleaning and reassembly. Have a good one. Geo


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## David R (Jun 15, 2008)

where will i find the carb info ... i do know its a zama? ....will the kit have all the gaskets i need? the mixture screw (1) has some sort of limiter on it ... i would guess it is the idle mixture ... i didnt see another, but it doesnt mean it isnt there!


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## nightmoves44 (Jun 11, 2008)

*same*

Ive had about the same problem,read my posts may help you.Most of us are asking the same questions.good luck on yours


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## dawgpile (Apr 28, 2008)

In addition to the aforementioned suggestions, make sure the fuel filter in the tank is not clogged. Remove and check it. You should be able to suck and blow air through this easily. Don't just do a visual inspection. You can't tell if it's clogged by just looking. If you have any doubt, go ahead and replace it. A clogged filter can cause the symptoms you describe of needing to be choked to run and the primer not being able to draw in fuel.

Keep us posted!


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## dawgpile (Apr 28, 2008)

You can see a parts breakdown on the Sears Parts site if you don't have one. There are 2 different carb kits. One is just gaskets and diaphragms. The other is a 'rebuild' kit that will have a new needle, control arm, and some other mechanical parts, in addition to the gaskets/diaphragms. While you can certainly order parts from Sears, they are generally not too competitive on price. Examine the carb and you should see some numbers/letters on it. You can go to the Zama website under the Service/Aftermarket tab and look at the document call the Quick Kit Cross reference. Find your carb in that doc, and take the number for the kit you need to your local repair/parts place. There is a good chance they may stock the kit or most certainly can order it. Here is the link to the doc I reference...

http://www.zamacarb.com/tips.html

IMHO, the majority of the time you can get by with just new gaskets and diaphragms. You only need the rebuild kit if you believe the engine has 'a lot of miles on it' and those mechanical parts are worn. Your call. As Geo mentioned, when you pull it apart, spray it thoroughly with cleaner through all the orifices. I don't see a need to remove the mixture screws and wouldn't before trying to get it going with new fuel lines, filter, gaskets and diaphragm and primer bulb if you think it needs it.

Most of the debris that makes it into the fuel line if the filter comes off is caught in a screen on the pump diaphragm side of the carb. You'll see it when you remove the cover that has the idle adjustment screw on it and then remove the gasket and pump diaphragm. Cleans out real easy when you spray it. That's why I wouldn't mess with removing the mixture screws at this juncture.


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## David R (Jun 15, 2008)

you guys are the greatest ... i found a small shop in town that has all the stuff i need to rebuild / replace these parts .... thanks alot, and i will keep you updated ....
in exchange for the help, i would like to offer any engineering advice / problem solving issues ... (senior mechanical design engineer, speciality machines, 30 yrs experience)


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## dawgpile (Apr 28, 2008)

BTW David, as an engineer you'll appreciate the richness of info available in the Zama Technical Guide(16 pages) on the same page as the Cross Ref doc. (I know I do:thumbsup Download that and have a look. Very informative and keep in mind the other two major carb manufacturers, Walbro and Tillotson have similar info on their sites, in case you endeavor to repair another 2 cycle engine with one of their carbs.


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## David R (Jun 15, 2008)

*It WORKS!!!!!*

Thanks for all your help ... the new parts did it .... starts on the first pull, idles smoothly and runs great (without the choke) ... that weenie that sold me this thing thought he hosed me good .... i got it for $25 ... spent $10 and its a champ!!!!!!!!!! looks like its brand new ... just bought a blower/vac for it too


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## geogrubb (Jul 28, 2006)

There is nothing greater than hearing that a suggestion made on the forum helped someone fix something, it saves money and keeps useable equipment out of the landfills. Have a good one. Geo


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