about 6-7 years old.  cranks very easy, idles fine, but when I give it gas it kinda ramps up but then quickly just dies.  theres a screw on there where I can adjust the idling up or down, this doesnt seem to help either way.  VERY odd that I can raise the spinning head up in the air and it seems to throttle up OK like that.

i first started noticing this a few years ago, started to progressively get worse, now its just unusable.  i took it to the shop last year to tune it up i think prob al lthey did was change the spark plug and charge me like 50bucks.

Check the filter position inside the tank. Fuel filters are meant to move within the tank when operating position is changed on most trimmers.

Sounds like your filter is either stuck in an odd position or not connected to the fuel line inside the tank at all. Especially if it runs in one position fine but no others.

Hope this helps

I'd flush the carb journals while you're working on it.

I had a 4 stroke Troybilt and I became wizard at taking apart, cleaning, reinstalling the carb.  

My dad ran ethanol gas in it for a summer.  Never ran well after that.

If it's like any other power equipment it's cheaper to just throw a whole new carb on it rather than messing with the old one.

Also check the exhaust to see if it has a spark arrestor and if it's plugged up.

well i took off and apart the carb.  ive never run ethanol gas in it over the past 6-7 years.  this thing looks pristine.  at least to my laymans eyes.




i also took fuel tank out to take carb off.  the little swigning weight piston dealio down in there does seem to move around.  i cant really do much else though?  replace fuel tank?  try a gravity feed?  

but i did notice this, and yall tell me what you think:



so there are 2 cables coming off the throttle assembly, 1 cable is just the mechanical steel braid throttle control.  but this one we see here is the kill switch cable; its got 2 wires red & black and this is the red wire we see here exposed (though theres no exposed actual wire) because of some insulation wear/degrade of the outer cable.  is it possible that voltages are high enough that when I throttle up such that it arcs to ground/chassis there and thinks i hit kill switch?  or something along those lines?


and now i have to figurte out how to reassemble the pull start spring thing.  wtf?  do i pre-wind it somehow?  but how to keep the wind tigh while assembling???
i guess next i can try to look at the exhaust thing.  thanks all for the help

You can't see buildup in the journals, the passageways are covered.  The big voids aren't the issue, it's the tiny journals that collect gunk.


Get you an old Rubbermaid container and put the carb pieces in it.  Soak the parts in carb cleaner.  Using the plastic straw on the carb cleaner, blast all of the journals in both halves.  Wear eye protection because it will blast out into your face.

You've got spark and air.  I think fuel delivery is the issue.  I'd also go ahead and replace fuel lines.  I'd also check the primer bulb and make sure it isn't hardened...If it is, replace it.  I've had hard primer bulbs create similar issues since they don't seal well and reduce vacuum in the fuel lines.

Sounds like a lot of stuff, but you're only gonna be out 15 bucks or so.

ETA: I'd replace that cable if I were you.  You've already got it apart.

well at this point since the thing is 7 year old im thinking to just buy new carb, tank/lines, air purge primer bulb, spark plug (its only 2 yrs old now though), kill cable, and gaskets; $60 after shipping, from ereplacementparts:

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but now it seems ive broke off this little plastic guide key (there are 2 of them) that sits on a spring on the fan blade assembly on the back of the motor where the pull start housing engages on.  i cant seem to find this tiny part anywhere. FML

I would start with the lines.  Cheap first step test.  Unless it's time sensitive, then just get it all so you can fix it quick.

FWIW, I bought a Troy Built trimmer years ago from lowes.  Worked great for about 87 seconds.  Then I had to adjust the carb, but it required a proprietary tool to do so.  I dremeled my own fitting and it worked okay for a year or so, then just shit the bed.  Fuel lines looked 20 years old, all yellow and brittle.  The throttle assembly looked like it was a WW2 surplus item.  I threw it away and said never again for TB.  Went Stihl. Paid a lot but the whole buy once, cry once thing is really true for shit like this.

Had the same issue with mine years ago.  Fuel line in the tank had a crack in it.

I had a leaf blower that did that . Found out the fuel lines were collapsing.They were very gooeyand rubbery.  I replaced those and now it works fine.

Make sure the air filter isn't clogged. When you turn up the throttle it adds more fuel into the carb and needs more air to go along with it.

Also take the air filter completely off and start it, and then spray some starter fluid into the air intake, which should burn out anything clogging the carb. Try throttling it up and if it starts to "choke" then spray more starter fluid until it stabilizes.

Which reminds me--make sure the choke is off...

check exhaust too... sometimes (on my stihl) there is a removable spark arrestor which can carbon up... just went through that with my blower.