STHIL FS90R - Where is the Spark Arrestor?

[Shawn R.]

This weed eater has been getting weaker and weaker over the past 2 weeks and now it is so weak, I can barely cut with it. After doing some research and reading the manual, it says that the Spark Arrestor may be clogged with carbon build-up. And that it is located behind the muffler. Well, I just took off the muffler and there was something behind it but not exactly what I was looking for. So, I found this:



And I was expecting to find this: When I searched for a new spark arrestor for the FS90R, this is what came up. So, where is this screen?

 

[Shawn R.]

This is the side of the weed eater where I took off the muffler and that piece of cardboard:

 

[Rivets]

Over the exhaust hole on the front of the muffler, under the exhaust deflector.

 

[Shawn R.]

Ok. I checked and the screen is missing. It was never on there. This was my dad's trimmer btw. I'll just order a new screen and put it on. The trimmer is still running weak. What else can cause it to act like this? I took out the air filter and tried that but still the same result.

 

[Hammermechanicman]

Possible causes:
Scored piston/cylinder scored
Valves out of adjustment (common)
Valve cover gasket not sealed
Bad leaking crank seals (common)
Crankcase pan not sealed (common)
Worn down cam
Clogged fuel filter
Carb issue

 

[Shawn R.]

Ok. Thanks for the info.

 

[Fish]

Ok. Thanks for the info.

Take off the plug and put up a pic of the tip of it.

 

[Hammermechanicman]

From the pic I would guess it needs the valves adjusted and new gasket and it needs crank seals and the pan resealed which is very common on high hour 4 mix engines. That is the rustiest valve cover I have seen on a 4 mix

 

[tgzzzz]

4 mix engines

a very apt designation

 

[Shawn R.]

Take off the plug and put up a pic of the tip of it.

Hey. I actually put a new spark plug in it a few weeks ago. I took the weed eater to M&M Enterprises and dropped it off. Two hours later, they rang me up and told me that it was ready. Total bill came to $51.89. They cleaned it up, used carb cleaner on it, put in a new air filter (cause I took the old one out), and they adjusted the valves. The guy who worked on it said the valves were tight and that's why it was so hard to crank up. The cord was really hard to pull. And also it ran weak. Now it's running like it's brand new! They didn't mention putting in a new spark arrestor screen. I guess it doesn't need it.