The air leak I'm talking about wouldn't show up as bubbles in fuel line.
If cylinder has air leak, it will alter the fuel/air mix in the cylinder, making it run lean.
jiggling the choke would compensate for this.
thanks,

Glenum, the screws were tight, but I took the plastic mount completely off to inspect for cracks or damage but found no problem. Reinstalled the piece and tightened the screws firmly, but still the same problem.
Thanks for the suggestion anyway, I see how it could have caused the same problem.

The best way to test for an air leak is to a Pressure/Vac test. You can do a cheap test by putting soapy water or oil on your crank seals, but this requires the engine to be running to see well. To do a press/vac test you'll need something to create pressure and vacuum (I have a Mity-Vac). It's easy to find something to create pressure with a gauge, it is the vac that you should make sure the tool can do if you go this route. You'll also need to cover the intake and exhaust ports, I use a piece of plumbers rubber wrap. You can put the seal between the muffler and exhaust port and between the carb and intake port. You want to make sure that you do not pressure the carburetor as you can ruin it. I believe you pressure and vac to 3.5 psi but double check before doing it. Too much and you can ruin the seals, where the crank comes out of the engine case. Your engine should hold the press/vac for about 1 minute IIRC. If it fails the test then you will need to find out what is allowing the flow of air in and out of your engine. If you can't find the culprit, the best way to do it is to pressure the engine and dunk it in water. You'll see air bubbles where the leak is. Of course, take off your ignition module before doing this.

I've done this sort of test twice and I think I can do it in under 2 hours. At shops I think they could probably do it in under 30 minutes. You'll just have to decide if this engine is worth that amount of work.

Thanks for the info Masiman. I've already got more time in this trimmer than I care to admit and have gotten nowhere. I'm not real fond of these big box store 2 strokes as it is.
I think I may just give my dad an early fathers day present, perhaps a Stihl or an Echo since I've never been disappointed by either.

That is my thought on also on this engine. I am guessing this is a I personally have a Stihl trimmer, which I really like. Although, I know I would probably any of the other manufacturers trimmers in the $250+ range. Decide if you need to use the trimmer as a brushcutter or not. If you need to be able to do brushcutting, you'll spend a little more for a bigger engine and a solid shaft. If you don't need it, you can save a little money and have a lighter machine.

Probably worn out or cylinder wall scrtched or scored causing low compression? I'd see if it has any compression? If the three or four screws that hole the head on are tight probably worn out from too little oil in the gas if it's a two stroke? too lazy to look up the model number. Hundred of them ususally on ebay, get one for 5 or 10 bucks and swap out the piston and jug. Done that quite a few times with homelite brands which by the way is one of the easiest weedwacker to work on.

I forgot to mention the compression test that rcmoser suggested.

The compression test will check the integrity of the combustion chamber. Can it hold the charge without letting your mixture leak out of the combustion chamber by the piston and rings and into the crankcase. On two strokes you should be getting @150-200 psi. At least that is what chainsaws should be. I'll assume that other small two strokes are the same but someone correct me if I am wrong. A much easier test to do than pressure/vac.

The pressure/vac test ensures the integrity of the cylinder as a whole.

Thanks to all for the advice and suggestions. I'll have the compression checked and if it fails I'll pull the carb that I just rebuilt and chunk the rest. Dang I'm a packrat, I just can't bring myself to throw away a perfectly good rebuilt carb!

Zero: Don't feel Bad , We all do the Same . I have an Old Weed Eater 1700 that just won't die , I have to set the carb up every yr. But it still runs great for camp usage. I have two cast off Weed Eaters also just for parts should I need then of about the same vintage lol .

Success at last!!! Sometimes itÂs just plain awkward admitting to a careless error, but in hopes that it helps someone elseÂÂ.here goes. I had so much time in this project I just couldnÂt just abandon it without answers or without at least learning something. Just to satisfy my own curiosity I purchased a compression tester, (which I should have bought earlier.) Surprisingly the compression pumped up quickly to 138, so now the carb is once again suspect. Keep in mind, this is the new style Zama carb with those dang tamper proof adjustments, thus the one thing I never did when I rebuilt the carb was to remove the H & L adjusting screws. I got busy with the dremel tool and made a tool to fit them, removed the screws, sprayed cleaner in the holes and replaced the adjusting screws. I set both to 1 ½ turns, cranked it up, touched up the H & L adjustments and it ran like new again. As the famous radio commentator Paul Harvey once so eloquently said, "and now you knowÂÂÂthe rest of the story."

I am having issues with a TB trimmer. I believe it to be a four stroke? It starts right up per the directions but once hot, it will shut off if I am not on the throttle---it especially struggles if I move the choke to the third position. Tonight, it even bogged down for no reason---as in, I wasn't cutting anything---and the entire machine felt unstable like it was being ripped from my grip. I don't expect anyone to help me but heck, any information would be helpful.

IMO Apache RP, Post a new post with your current history of all you have done to solve this matter. Look at the dates of this post’s info. I have gotten caught and maybe due to a search vs being active on the board .

From my limited experience with the 4cycle I’ll be concered with the age of your treated or untreated fuel and “Oil Level” in the engine.

My TroyBilt TB25ET starts easily and runs good until I throttle up. The choke flip opens up and the engine shut down. It will start back up again, but as soon as the choke flip snaps open, the engine shuts down again. I cant' get past the throttle idle position. Any suggestions. My fuel lines, filter and air filter have been replaced.

Can you post a diagram of
your carb or show what mechanics holds the choke closed? I feel a spring is missing, lost tension or not correctly placed.

It's hard to find a breakdown of the carb. The part number is 753-04338. (Replacement parts.com has several views. There's a idle adjustment screw on top that seems to do very little. Seems to just get in the path of the throttle cable attaching hole. The start procedure is to Flip (Choke), Prime (10 times), Pull. The choke seems spring loaded and locks in place. I can let it idle (choke on) for several minutes and it idles. The throttle snaps the choke open and then the shutdown.

I needed an idle adjustment to fix the hard running. I also suspected a few minor tweaks with routine upkeep because I originally sent it out but that person really didn't do me any favors---creating more work and confusion.

So I had my uncle check it out. If your adjustment screw seems to do very little, is there a chance it is turned too far in one direction? I'm not an expert by any stretch but my TB has run well ever since my uncle adjusted it. You may also want to check your air filter and be sure it is clean.

Good for you that you have an
Uncle with Good Skills to learn from.
Good Skills are becoming Rare!

Good point on some work need
to be performed by a “Known Professional”.
At the same time IMO we need to know and practice basic up-keep “And Use”
on our equipment. That’s why it is not a
good practice to loan equipment. If I
know you well enough to loan you power equipment. I’ll be visiting you while you use my
equipment. LOL!

I hate to think some people
do not know any better when they miss-use power equipment. Depending on there background, I feel they
have not learned how to safely use or not overuse power equipment.

I would feel if an adjustment
screw is making a difference and it stops changing RPM, Accelerating
Performance or Etc. it is out of range.

For the record, I sent out to get worked on and it didn't go well. But I do try to learn and know when to ask for help. I can't say the same for some people close to me. lol.

That is why I don't like loaning out equipment. Any time I lend something out to those people or share something with them, I get the short end of the stick. It is almost comical but not really because I am the opposite. If someone lends me something, they get it returned in the same or better condition---a full gas tank, a new saw blade, etc. I wouldn't feel right if I did it any other way. I'm certain my uncle feels the same about the same people. He once found them some equipment, fixed it up, and within a day, they did something to leave it not working. Instead of going directly to him for help, they decided they could tear it apart and fix it but they couldn't and he ended up returning their money. They honestly did the same to a car and needed to buy a brand new one. Crazy.

Apache RP, I Feel Your Pains! I have been in the business of Learning And
Sharing since 6th grade (1958).
I started working for different Techs and Craftsmen as they saw I had an
interest to Work And Learn. I started
Sharing then as I learned More and wondered why this was not a common cycle for
All. Even today I have to remember, “We
Are Not All The Same Or on The Same Page”.

I hate it when I realize a
Person was out to use me vs “Allowing Me To Help Them”. This has slowed my efforts to help not to
Mention What My Body And Drs Are Saying.

Keep Your Spirit!!

PS. Is ewalk Still Sharing?

Sounds like the breather hole in the gas cap was plugged up, by a leetle bug!?

I know-i'm way late!

I've had that feeling many times with these particular people. Usually, I end up having extra work to do in someway or another and it is highly frustrating. It doesn't mean I won't help if asked but I'd rather do the work myself than loan something out---much easier to do it right myself than the alternative. Forgive me loger_gw, I don't understand the ewalk reference if I am supposed to?

I doubt a bug was the culprit in my case but it does remind of a project. I found a critter friend one day while filling the gas tank---I definitely did a double take because he was oblivious to me. But I have holes to look for and seal in the shed.

ewalk shared in this info up
above in 2010 (listed below). I have
note seen shared info from him since Approx 2012. I miss his Tips! Plus, wonder about him being well.

ewalk

"Zero: Don't feel Bad ,
We all do the Same . I have an Old Weed Eater 1700 that just won't die , I have
to set the carb up every yr. But it still runs great for camp usage. I have two
cast off Weed Eaters also just for parts should I need then of about the same
vintage lol ."

March 27, 2010 at 11:28AM

I've been reading these comments and none of the ideas seem to be an issue for me and my TB 4 cycle trimmer. I changed the oil and replaced the fuel tank, air filter, and carb. The unit, when it gets started, will idle in position 2 or 3. When I put it in pos 3 and throttle up it bucks like it has a bad cylinder, like my car once had. Any chance it may be the spark plug? It's never been changed but no one has mentioned this as a possible cause for rough a throttle. I'm going to try it and see if it may be the cause. If not, this will be the last Troy Bilt thing I ever buy again(this was the second trimmer after my first 2 cycle one). I got it because of the interchangeable head option.

d69: Rather sketchy details , usually spark plugs should be inspected annually and cleaned or replaced. Also tuning of your carb and valve adjustments are required when warranted. Do you use ethanol fuel , do you use fuel conditioner on a regular basis ? From the shudder or bucking description you may have either carb or valve train issues . Pull your plug and describe the condition and colouration to us ...aka Ewalk Thanks !

I have had two experiences
helping neighbors with Troy Bilt Trimmers (TB6044XP)

1. The 1st over
fill his with oil. 2 OZ is a small
amount compared to 4 cycle equipment. We
did not ck to see how much it was over filled but the foaming, smoking vibrating
indicated too much oil IMO. We drained
and refilled using the listed steps, oil fill window and measured and it ran
fine

2. The model is designed to
electric start or pull start. The 2nd stopped
turning the engine over to manually start.
It was given to me and it started using the “Electric Start Hand Held
Attachment (and ran fine). Knowing it
runs, I investigated and found the lock washers were too loose for the manual
start to work. Getting it apart to replace the washers is another chapter.

Applying force to replace the
washers the threaded shaft snapped as I re-tightened. Another chapter without a special adapter and
torque specs. Thinking I had broken the
crank, I still wanted to see more to discover I broke an adapter. I felt the adapter would be affordable until
I learned it’s only sold in a complete short block (73.00).

I donated the unit and
promised we would find a bad Short block for that part on the curb vs
Ebay. See the attachment and give your
opinion of the adapter purpose.

I purchased one of these trimmers new and it did not want to run without the choke being on. It would stall whenever I hit the throttle and would buck hard enough to nearly pull the trimmer out of my hand. The fix for mine was replacing the fuel lines, especially the one that goes to the filter in the tank. The fuel line was defective from the factory and was brittle and had small cracks that were almost unnoticeable. This condition allowed the line to suck in air when it was running creating a lean out condition. Keep in mind the trimmer was brand new and the the fuel line looked new. It still runs good after replacing the lines two years ago. Make sure your replacement lines are the correct outside diameter to prevent leaking where it goes through the gas tank. Expect to replace the primer bulb sooner than later as well. Good luck!

One tank same problem won't run. Tried everything everything is tight. What it boils down to is you do a damn thing with it except chunk it across the yard. This is one worthless pos

My Tb weedeater will crank fine and idle fine but when I pick it up it goes dead. It seems like I hit the kill switch. It will start rite back up

Lane,

Please give some history of your trimmer
and services, including age and hrs.
If it starts and idles it should Run.
I feel if moving the trimmer is an issue it could be related to the
following.

1. Trash in the carb restricting fuel
   flow.
2. The fuel line in the tank is
   changing positions and could be cracked, sucking air.
3. Trash in the fuel circuit that is
   trapped and fine wire or compressed air will move.
4. Know your Carb adjustments before
   pulling the screws (count inward turns.
5. Ck the small screen in the carb. A
   pencil’s eraser will reseat it if pulled.
6. If a spark arrestor is on the
   muffler, please check it. Heat/brush screen if needed.
7. Please share what you find or some
   feed back.

Idle speed set too low . one quarter turn in will help !

Having read thru the post aimed my efforts to the carburetor. I too had a nearly new TB 22 2 cycle string trimmer that started from the choked position but when moved to the 2 nd positioned would run but would die unless jiggled between the full choke. The third position, full run was not even possible. The air and fuel needles had a speck of debris I was sure of. The needle adjustments are counter sunk into carb housing requiring a special tool. Didn’t have one, considered machining my own, machinist for 35 years, but having a Dremel tool decided to cut a shallow screw driver slot in in head of each air and fuel adjusters. I did not even remove needle valves but opened each up a half turned, cranked it over a few times to flush debris thru carb, returned needles to original position and wah-la been running strong since.

Yep , if your in a bind the dremel trick will get you up and running !

I have a TB575EC that starts fine Run good for a little while then dies like kill switch was hit.Then starts up first pull.It does not stay off long enough to test for spark

Bad coil !

I have a tb 525 ec. The fuel lines cracked so we ordered a tank with new lines, now won't start at all. Anybody know why?

Did you refill the new tank ? lol .

are you sure the lines are attached to the carb right?

Ah 300 ' yeah have to let them run with the line prior to setting the hook Bud !

Yes sir I have been reading up on this post and I have a Troy Bilt 27cc tb80ec I bought it offline from the this guy... had problems with it ever since... It fires up and runs great now that I have changed spark plug clean the carburetor I've even switched to a new carburetor... it fires up and runs good for about 5 minutes and then starts trying to bog down and runs irregularly jerks tries to back fire... I useused the hacksaw trick on the carburetor the original one... adjusting the screws seemed to help a little but still minutes once it gets warmed up starts losing power... the only things I haven't done yet is change the ignition switch and replace the Piston flywheel or clutch.... I could really use some help on this one... I am by no means a small engine guy I didn't learn most of this until I pick you up junker up.. hope you can help me solve it ....ssewalk.. thanks in advance

Since it is a used unit the causation can be more troublesome . You have pretty well checked , cleaned or replaced the normal areas of concern . The ignition switch may be faulty as you have indicated which can be bypassed . Secondarily and more likely is that your coil is heating up and breaking down . They are inexpensive on eBay . I would also advise since it is used to ensure your fuel filter and air filter and gas cap vent are clean and check the cylinder and headbolts are tight roy- bilt and ryobi have fastener issues Good luck Bud !

you have a vented gas cap. try running it with the gas cap loose.

Yes I have cleaned the gas cap and I have ran it with it loose I've checked my gas lines still same thing... I was going to go is in ignition next just because it is the cheapest thing on the list to change next... I only spent $43 on the if I could only spend 43 more to fix it I would be okay with that... thank you I will let you know how it turns out....

Were there any signs of trash in the carb when you cleaned it? If so, even with the new, ck to see if additional varnish or etc is on the small screen in the carb restricting gas flow. If so , clean the tank and complete carb system “Again”! I gave my 4-cycle TB above away to try to keep my Sanity. Good Luck! If this is not fun, “Life is too Short”!

10% chance it's the Switch , 75% chance it's the coil , 15 % chance faulty gaskets or seals .

woooooo..... I'd almost given up on darn thing

It was the coil..... I'm glad everything else got changed and replaced but man that was a process... I have must have watched 50 YouTube video

Can't thank you fellas enough

My $43 Troy-Bilt weedeater shall we live on LOL

Yeah repaired enough trimmers in my day . Must be the most repeat customers i encounter other than routine chainsaw servicing lol. Keep the fuel treated and you will have plenty more yrs of usage .

What would cause my TB22 weed eater to get real hot then bog down and shut off, after it cools it will start back up, but not as easy as it used too since it started getting hot, I cleaned the air filter, which wasn't that dirty, I checked the muffler and screen and it still looked almost new, tried adjusting the carb screws and still no better, I cleaned and checked the gap in the spark plug as well, I've had this weed eater for about 3 years now and never a problem until today, any ideas??