# Stihl FS85 carb problem



## mmyer2g

Hi. This is a great forum. I just joined. I'm new to forums so bear with me. I'm not that knowledgeable about carbs. I have a Stihl FS85T trimmer. I searched around and was told I either have a Zama or Walbro carb. After the trimmer would barely start and then not at all, I took it to a small engine shop. They told me I needed a new carburator. I thought that was a little unusual. After asking questions they finally told me more details and said it couldn't be rebuilt. They apparently cleaned it and it still wouldn't start then either. I hardly ever let the trimmer sit with fuel and I service it myself according to manual every year....new filter, spark plug, etc. They told me the cost of new one is $115. I assume this is additional to the initial diagnosis cost. Is this typical? Is this something I can do myself by buying the correct model carb and replacing it? Can it be rebuilt with the kit or are they just pulling my leg?


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## Rookie1

I had a similar situation where a shop charged me $85.00 to "get it running", ran for a week and died again.

I installed the rebuild kit myself and now it starts on the first pull every time.

A carb kit is $10.00. 
I say go for it. What have you got to lose?


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## repair_guy

Here is some 2-cycle carb.sites which might be useful.

http://www.powerequipmentandparts.com/walbro_carburetors.htm

http://www.psep.biz/store/walbro_carburetor_parts.htm

http://www.zamacarb.com


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## digger350

*i may can save a lot of headaches*

i may be able to save people a lot of headaches and money...i bought a new mtd weedeater for 10 bucks because the guy said it would only start and die so i took the muffler off and some have a pollution control crap screen between the muffler and engine that gets clogged up i took mine off and it runs like new now i will always check this before even fooling with carbs from now on


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## mmyer2g

Thanks for the input. I found out the carb is a Zama C1QS45 or S63. Apparently the number changed. Zama no longer makes this carb and I was told by the small engine shop that Walbro does not make a replacement. I've started searching the web to find one or a replacement brand but not much luck so far. If this was a $90 weedeater I wouldn't worry about it, but I paid $400 for this Stihl FS85 and got the edger shaft to go with it. Any more ideas I might consider? Thanks


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## Rookie1

Try Ebay, you'd be suprised what you find on there.


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## mmyer2g

For future info and those out there that have a Stihl weedeater, the brand carb I have for my model FS85 is Zama C1QS56. The shop I went to got the wrong model number. I ended up finding the carb at another dealer in town for $60. The shop I went to couldn't find it. I ended up calling the Stihl folks myself and found out the correct part number. It runs fine now. I have the old carb to play around with now. Thanks for the help.


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## revjohnnunes

*FS85T Carb Problem*

I've had my FS85T for 8 years. Great product. I just developed my first problem today. I believe it is the carb, but troubleshooting simple stuff first. How did you find out which carb you had, and is there a marking. Did you have to take the carb. off to I.D. it?


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## 30yearTech

If it's a slide valve it's probably a "TK", if its a butterfly or rotary valve then it could be a "Zama" or "Walbro" brand, I don't think Stihl has used any "Tillotson" carburetors in a long time. In any case the mfg. should be cast onto the carburetor body or pump cover.


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## RMHayes1954

*Replacement Zama carb*

I fought with my FS85 carb for 3 days. Cleaned, rebuild kit, new primer, adjustments, etc. with only a tease as a result (went from not starting at all to starting and idling but stall when it gets the trigger).

Finally gave up and called the dealer - it would take a week for them to look at it. On an off chance I asked about a replacement for my Zama C10-s63a carb. They had one - for $23!!! Apparently there was a 50% cut in Zama carb prices just recently.

If you have an FS85 with a few years on it, and you sometimes get hesitation when you pull the trigger (especially when cold) then RUN to your Stihl dealer and get this carb. It's a direct bolt-on 5-minute replacement job, already adjusted. Mine started on the first pull and loves the trigger. I'm a happy trimmer once more. 
BTW-consider changing the fuel lines and filter so you don't get crumbling old rubber pieces in your new carb.


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## AltshuleS

*Stihl FS 85 starting problems*

Here's a possible solution to the above problem. Check to make sure that 3 bolts holding the crankcase to the cylinder head are tight. It won't suck fuel into the combustion chamber if they are loose. I think that the problem slowly emerged and my FS 85's performance slowly dropped over a period of time. It runs great now, perhaps better than ever or at least as long as I can recall. the only question is what is the correct setting on the carbureator adjustment? Is it possible to over rev the motor? One clue with the above problem was that it would fire after 4-5 pulls afte squirting starting fluid into the carb, but wouldn't run long. So, I new that I had ignition, but no fuel...


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## betdy1345

*to AltshuleS*

for that one don't forget the stupid simple stuff like me. check the fuel line for a pinch or the filter in the gas tank. to see if it's the filter just remove it and shove the end of the gas line back into the gas and try to start. if it is 100% difference problem solved, but remember to put in a new filter. i fought a chainsaw that did the same thing for everything but the filter for 3 months on and off. when i checked the filter i felt pretty dense. my lesson learned. don't forget the basics!!!!! not saying you are wrong and realize mmyer2g has problem solved, but this could save someone that $85 carb job from a greedy shop.


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## Don L

RMHayes1954 said:


> I fought with my FS85 carb for 3 days. Cleaned, rebuild kit, new primer, adjustments, etc. with only a tease as a result (went from not starting at all to starting and idling but stall when it gets the trigger).
> 
> Finally gave up and called the dealer - it would take a week for them to look at it. On an off chance I asked about a replacement for my Zama C10-s63a carb. They had one - for $23!!! Apparently there was a 50% cut in Zama carb prices just recently.
> 
> If you have an FS85 with a few years on it, and you sometimes get hesitation when you pull the trigger (especially when cold) then RUN to your Stihl dealer and get this carb. It's a direct bolt-on 5-minute replacement job, already adjusted. Mine started on the first pull and loves the trigger. I'm a happy trimmer once more.
> BTW-consider changing the fuel lines and filter so you don't get crumbling old rubber pieces in your new carb.


Stihl bought Zama a year or two ago.The prices on a lot of replacement carbs dropped drastically.Be very careful with ethanol and carb cleaners,some carbs have non servicable check valves that swell closed when exposed to certain chemicals.
Don


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## Novaris

something else that should be looked at is the fact that 2 stroke oils are not properly bonding with ethanol fuels and the ethonal fuels only need 2-4 weeks to breakdown seperate and place water into the fuel tank of your equiptment it was brought to us by husquvarna that this was happening and now we are recommending that all users use Stihl high performance XP 2 stroke mix in there fuels it has a easier time bonding with the ethonal fuels and it cleans the heads but at current time we do not know if this is preventing ring gummage

Small Engine Repairman


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