Chainsaw Repair

Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Stihl => Topic started by: Ellinas on April 10, 2014, 01:56:58 pm

Title: Stihl fs45 problem
Post by: Ellinas on April 10, 2014, 01:56:58 pm
I would like to have your opinion about a problem my stihl fs45 trimmer faces

The thing is that when i push the throtle with open choke then the trimmer shuts down
but if the choke is closed the machine works perfect and as i know the order is not correct!

I Changed the fuell tank ( had some cracks ) and the fuell line but the problem doesnt desapeared.

I made a repair to the carb (Metering diaphragm and the Gaskets) i also clean it but the problem is still there...

If anyone knows what is going on please answer me.
Title: Re: Stihl fs45 problem
Post by: Fish on April 10, 2014, 02:16:14 pm
Take a 5/8 socket wrench and remove the exhaust tube and try to run it.
Title: Re: Stihl fs45 problem
Post by: 660magnum on April 10, 2014, 02:20:05 pm
I had trouble with my FS55R (same engine) as the idle circuit was plugged. I ran a tiny wire through all the passages I could get to, had the needles out, etc. Didn't change anything. The carb had some kind of white corrosion in it.

I bought a new carb from the Stihl dealer and the problems went away. That was three years ago. The carb was like $28
Title: Re: Stihl fs45 problem
Post by: 660magnum on April 10, 2014, 02:20:50 pm
I took the screen off the exhaust tube on mine.
Title: Re: Stihl fs45 problem
Post by: Ellinas on April 10, 2014, 03:13:19 pm
Thank you for your answers!

Fish i did what you describe but unfortunatelly no changes...

660magnum i went to a Stihl dealer and told me to throught it away and buy a new one (?)!
after a week i decide to try fix it myself. When i called him to ask for the carburetor told me that the
cost of it was 75 euros, so i prefered to clean it and buy the repair kit for about 20 euros.

I am trying to find a fix two weeks now but everything i do it's useless it works fine only when the choke is closed
when i open the choke and push the throthle the engine stops.

Thanks a lot.
Title: Re: Stihl fs45 problem
Post by: 660magnum on April 10, 2014, 03:49:32 pm
The carb has a restriction in it somewhere?
Title: Re: Stihl fs45 problem
Post by: H 2 H on April 10, 2014, 05:16:29 pm
IMO the white stuff in the carb is "E" fuel I've seen it before

I have found "E" fuel plugs alot of things up

After a number of tanks of fuel I took that exhaust tube off my FS45

Exhaust tube is so small and gets plugged easy

This is mine that I bought a few year back (when it was new)

(http://i59.photobucket.com/albums/g317/H2H_PHOTOS/DSC_5033_zps97712051.jpg)
Title: Re: Stihl fs45 problem
Post by: 660magnum on April 10, 2014, 05:41:58 pm
I have three of these. One was originally a FS45 and I made a FS55R out of it. Another was originally a straight FS55 and I made a FS55R out of it also. Then I have a 3rd power head that I made into a FS45.
Title: Re: Stihl fs45 problem
Post by: Fish on April 10, 2014, 05:59:50 pm
I have parted out a few hundred of them, let me see what I can do...Stihl has been selling most of their common Zama carbs for @ $20-30 lately, to help with the fuel problems....
Title: Re: Stihl fs45 problem
Post by: tinkerswithengines on April 10, 2014, 09:32:08 pm
I have come across many carburetors that have been clogged by "white rust" from ethanol fuel and gummed up from stale fuel.

There are just some internal areas of these small carburetors that can not be addressed by running wire into the channels or in extreme cases, removing the welsh plugs. True, you can replace a Zama today for around $30 but when you don't have one in stock, or if its a older model that has been discontinued or if your dealing with a rather expensive Walbro, I'll usually just clean it.

The method I have had great success with in cleaning these carburetors is with a heating capible, ultra sonic machine. Completely disassemble the carburetor and remove all the visible gunk before putting it into the ultra sonic cleaner. I use Mechanic In A Bottle or Star-Tron in the machine, heated to 110 degrees F for 30 minutes. I reuse these products/cleaning solutions many times over.

Usually when I am waiting for the carburetor to clean, I change out the spark plug and air filter and replace the trimmer line or if its a saw, I'll sharpen the chain etc.

Hope this information I just posted helps someone out.

Dave
Title: Re: Stihl fs45 problem
Post by: 660magnum on April 10, 2014, 09:45:53 pm
I had the opinion three years ago that the white stuff was corrosion caused by water in the fuel. The fuel with the ethanol has the potential to hold a good bit of water before the ethanol and water precipitate out. This water laced ethanol component is reacting with the zinc diecasting the carb body is cast from.

I bought the weed whacker I was having trouble with from Craig's list and it was leaning against the Northwest side of the owners house trailer on the outside. So I assumed that water was a big part of the problem.

I have had not problem with it or the other Stihl weed whackers since then but I do not store them outside. 
Title: Re: Stihl fs45 problem
Post by: Ellinas on April 11, 2014, 07:09:15 am
660magnum I do not know what you mean with the restriction thing
do you think it would be a good idea to upload the parts diagram of the carb
in order you to have a clear picture of what is going on?

Title: Re: Stihl fs45 problem
Post by: 660magnum on April 11, 2014, 07:22:43 am
660magnum I do not know what you mean with the restriction thing
do you think it would be a good idea to upload the parts diagram of the carb
in order you to have a clear picture of what is going on?



Restriction:
Part of the fuel circuit in your carb is plugged?

If you know your carburetor number, you can look up all about it here: http://www.zamacarb.com/prod_lookup.cfm
Title: Re: Stihl fs45 problem
Post by: Ellinas on April 11, 2014, 08:13:25 am
Thanks a lot! i found my carb and as i saw its a Discontinued model
so now i am wondering why the Stihl dealer does not told me that...

Well because there are lot of stuff in the pictrures and i am not an expert
i have one more question. The parts manual that i found on the net includes
five or six carbs for the FS-45, is it possible to fit all of them to my machine or only
the one of them fits? because i saw that some models are not Discontinued. And
is there any way to be sure that the dealers price match the real price of the carb?
because i suspect that the dealer try to sell in a higher price.

Title: Re: Stihl fs45 problem
Post by: 660magnum on April 11, 2014, 08:24:48 am
Thanks a lot! i found my carb and as i saw its a Discontinued model
so now i am wondering why the Stihl dealer does not told me that...

Well because there are lot of stuff in the pictrures and i am not an expert
i have one more question. The parts manual that i found on the net includes
five or six carbs for the FS-45, is it possible to fit all of them to my machine or only
the one of them fits? because i saw that some models are not Discontinued. And
is there any way to be sure that the dealers price match the real price of the carb?
because i suspect that the dealer try to sell in a higher price.



I had the same problem. My carb had been discontinued also. Then there were so many other carburetors on the list?

I picked another carb that was not obsolete. I had to order it as the dealer did not have any of the optional carburetors. The dealer ordered two of them when he ordered mine.

I installed the carburetor and the engine started right up as if brand new and never had any trouble since then. I just ran this trimmer yesterday.