[pontiacmark]

Have a Troy Bilt 2 stroke string trimmer TB70SS model that I bought new last year. I emptied the tank at the end of last season and put Stabil in my can. First use this year it did 3/4 of the yard and stalled. It would not idle upon restart. I figured some gunk in the carb so I tore it down and cleaned it with carb cleaner in every passage I could find. Just a small amount of buildup around the needle and seat. I put it back together and it still would not idle. I tore it down one more time and cleaned as best I could and replaced the fuel lines and bulb. Same result, no idle unless I held the choke halfway open. Seems like it would be lean then. I am not sure what else to try. Spark arrestor was clean too and plugged looked fine and was gapped perfect. Maybe a vacuum leak through one of the gaskets? Any ideas? I almost want to toss it and go electric but I have a lot attachments I use with this thing.

[beemergary]

Is there a L-low side adjustment screw-back it out to richen it.

[pontiacmark]

I assume the screw you are referring to is one of these special type accessible through the hole in the top of the cover? If so, where is a good source for the tool?

[74gto]

Unfortunately, thanks to the EPA, the tool is not available to the general public. Any dealer caught selling tool can be subject to a large fine from the EPA.

[tdavidl]

Originally Posted by 74gto

Unfortunately, thanks to the EPA, the tool is not available to the general public. Any dealer caught selling tool can be subject to a large fine from the EPA.

two simple options then:

1. give away the tool
2. lose the tool & tell them where you lost it

[HaloMedic]

Same thing happened to me, did everything you did with the same results, then I got smart and went here bought a replacement carb and it runs like new
https://www.partstree.com/parts/?lc=troy_bilt

[pontiacmark]

Replacement carb about $75. New trimmer $109. May pass on replacing the carb.

[John V.]

According to what I read, the Troy-Bilt trimmer has an adjustable idle screw.

Use a small flat blade screwdriver inserted into a small hole, about the size of a pen tip, in the top right of the air filter cover.

Turn the screw clockwise 1/8 turn with engine running til it idles smoothly.

CCW 1/8 to stop the trimmer head from spinning at idle.

I don't own this trimmer so only telling you what I read.

My Ryobi wouldn't idle right, I discovered the head bolts had loosened after a couple years. Head actually was visibly moving up and down with each stroke of piston. Tightened 'em up and has run great since.

I've never used Stabil in my life and have always used up old gas at the start of every new season. But maybe your fuel mix itself is the problem especially since you put Stabil in it.

I'd mix up a new can with fresh gas and see if that works even before messing with the idle adjustment. And if so, next year, skip the Stabil.

[pontiacmark]

I did try a fresh can of gas/mix with the same effect.

I am going to make my own tool to adjust the idle mixture and then try the idle speed adjustment. The idle speed is probably not it as it will not run well at full throttle either.

[scott0]

There should be a screen on the muffler. Remove it and see if it is plugged. Those are the correct symptoms for that problem. I can't imagine the carb would just magically be out of adjustment.
Hope this helps! Scott0

[pontiacmark]

Already checked the spark arrestor screen and it was clear. Thanks.

[John V.]

I assume you checked the obvious dirty air filter.

The loose head bolts that caused the loss of power for me was a common problem for the Ryobi brand, guessing that isn't your problem with the T-B.

You should check for a cracked primer bulb, possible source of vac leak.

But I'm guessing carb adjustment is the likely issue you are having.

The story that the carb adjusting tools are illegal seems to be BS.

They are sold in lots of places.

You might check O'Reilly's, somebody claimed they sell 'em for small engines.

Otherwise, tons of places show them on-line, this is just one example (it also has all of the usual head types, so pretty versatile).

http://www.amazon.com/Performance-To...djustment+tool

Lots of DIY'ers have also improvised their own or cut a slot in the screw with a Dremel, stuff like that.

[pontiacmark]

Air filter was clean and primer bulb was already replaced.

[John V.]

Oops, forgot you mentioned bulb replacement in the O.P.

So get/make the carb adjustment tool and make sure to report back. Seems like the most likely problem after all you've done already and an almost new machine. I bet it will run great once you turn the screw a bit.

I suspect these things are tuned "lean" from the factory, but need a little more fuel after they've been run a bit. Hope so anyway, that would be a cheap fix.

[pontiacmark]

Cut slots in adjustment screws with Dremel. Couldn't get it to run enough to see results from adjustments. Gave up and bought a cheap electric trimmer for now as I don't have much yard to trim. I will keep playing with the gas model later and let you know.

[rexs73gto]

My trimmer runs bad to when it's close to idle but ok/good when it's at full pull. I've used mine for about 10 years now but I don't use the strings any more. I've used the blades for thelast 5 or so years & they work so much better. It makes them vibrate a little bit more but I can use mine to trim & if I turn it on it's side I can use it as an edger to.I've went through 2 sets of the blade ,, thats 12 blades as you have 3 blades on each trimmer but when you get your running again try the blades. If you have any small trees no bigger then an inch or so around it will cut them down & you'll never see them again. The junk that grows in between my garage & the neighobers garage is always a small jungle but using the blades I go through that stuff in no time at all. Instaed of an edger I use mine to cut the edge back where it grows over the edge of the blacktop in my driveway. The string won't touch it but the blades, I love them.

[pontiacmark]

Looking back, I wasn't real clear on a key point. Not only would it not idle, it wouldn't even run at full or half throttle without the choke half open/ closed.

[John V.]

Similar to what I recall the Ryobi doing with the loose head bolts. Struggled to start it, then would die when I opened the choke. So I ran it choked, but even then it lacked power. Sometimes it ran strong for a few moments, then it would slow down/lose power.

In my case, proved to be a massive vac leak as the head separated and closed with each piston stroke.

So maybe you are on the right track looking for a vac leak somewhere or maybe a fuel restriction (see below).

Are you sure you were turning the adj screw after you slotted it?

Did you notice a change in rpm at all as you turned the screw?

This video shows how to clean the internal carb screen. Says this screen is often the cause of sluggish running. Did you notice this screen when you had the carb disassembled?

http://www.how-to-diy.org/wnRbZFiXEu...retor-fix.html

[JLHarper]

Probably had old gas still in carb, since you said tank stabill added but didnt say you ran it through.

May require a good soaking...even a tear down and cleaning may not get it all un gunked, ime if old gas was in carb.

I run Marvel Mystery diluted through all of mine.

I get all of the neighbors gas machines every Spring...only time I see some of them...lol/.

Like posted the vacum leak from a crack is also a big problem, but bet your carb is still fouled.

[beemergary]

Originally Posted by beemergary

Is there a L-low side adjustment screw-back it out to richen it.

OK Plan B Did the diaphrams get put back in correctly? Try bending the needle arm for more fuel. Play with 2 cycles all the time and it usually the opposite with a flooding problem. Neeedle and seat not seating due to dirt or arm out of adjustment or bad diaphrams-holes or just dryed out and junk. You can also have problems with the spring under the arm but usually causes a flooding from not enough pressure on the needle and seat. Race vintage snowmobiles and carbs can be a nightmare.