Stihl got the Blues...!

[AltaLawnCare]

I've got Stihl problems. I have an old FS 80 trimmer, that when it gets hot - it wont take the gas, it just bogs and cuts off.

My new FS85 is starting to do the same! It's not as bad as the FS80, I can still use it.

The FS80, has had the following done to it so far...
New plug, Muffler cleaned out, air cleaner cleaned, gas changed, fuel filter cleaned, carb kit installed, firing checked, new fuel lines installed.

I run Amsoil 80 to one..(1/2 bottle to 2.5 gallons of gas)

Next, I'm gonna try some stihl oil, just to see if the new one will straighten out before it dies too!

Anyone have any ideas?? :confused:

[grasmo]

make sure the carb. idle and main circuits are adjusted, the fuel pump/needle tang is adjusted, and make sure you have a good cylinder.

[barnard]

The next time you run it runit until it bogs, then loosen the gas cap and see if it makes any difference. It might be a vent problem . Air can't get in the tank-gas won't get in the carb.

[General Grounds]

:blob3: gas cap all the way...

[olfrt]

Assuming this just started suddenly

When it is acting up check the spark to ensure that it is not a spark problem.

hope this helps

[AltaLawnCare]

Thanks, everybody. ;)

I hope its not a problem with Amsoil, I run it 80to1.

I rarely go wide open, most of the time I'm 3/4 throttle, and just hold it there. The guy working on it for me said that might be a problem - hes a very good mechanic, but works as a automotive mechanic, not small engine.

[Jeff in AL]

On the older unit, it will most likely be the muffler or exhaust port starting to stop up with carbon. If so, it will need to be cleaned out.
On the newer FS 80, I would check the coil. I have replaced probably 15 coils in the past 4 mo. Stihl has had a problem with some of the coils, and are now using a different manufacture for them.
To check the coil, run the unit as normal (wide open throttle) for about five minutes, and then shut unit off. Then let it sit for two or three minutes and then restart it. If it starts, most likely its NOT the coil. However, it probably won't start. In this case the coil is bad and will need to be replaced.
Here's the deal, while the engine is running, enough air passing over the engine is keeping the coil cool enough to work. When the engine is shut off, the engine temp. goes up for a short period of time, because there is no are blowing over the engine to cool it. While the engine is getting hotter after it has been shut off, there is a solder joint in the coil that breaks from the heat, and when the engine has had enough time to cool off, the solder joint makes connection again, and will run just fine untill the unit is shut off again.
One more thing you can also do to verify this is to remove the top orange engine cover, and look at the coil. The coils that have had the problem have a CLEAR potting compound on the top of the coil, and the replacment, or the known good coils have a black potting compound.
If the coil ends up being the problem, take it to your dealer, and they should replace it at NO charge to you.
The part number for the coil is 4137 400 1350

Hope this helps

Jeff

[Clewsew]

I know that this is late, but maybe better late then never. I believe that the Sthil 2 stroke engines run 50-1 for the oil mixture. if you are running 80-1 then you are most likely running the engine lean on oil, which would cause overheating and eventually damage to your engine!

Also, I have been told to run the engines is the best thing for them in keeping the muffler and screen from fouling(although I do not run WOT very ofter myself.) The 50-1 mixture is set to be optimum at WOT. Less then WOT causes the oil to be a richer mixture, causing fouling. In your case, your only running 3/4 throttle may have saved your engines.

One last note, my FS85 manual says that after running the unit hard to let it idle for a couple of minutes before turning it off. This is because the engine turning does create airflow to help cool the engine off.

Hope this helps,
Clewsew

[khouse]

I have ran Amsoil 100 to 1 since the late 70's. I have ran it in my Shindaiwa power head, Redmax trimmer, Stihl chain saws, Rm 125 Suzuki, lawnboy mowers. I have never had a major engine failure. It's been in a 1977 lawnboy since new. I'm sure at 80 to 1 your very safe. I do 3 lakes with the Redmax wide open for up to 4 hours strait. I would have to say the fuel cap,fuel filter or coil - in that order.

[AltaLawnCare]

Thanks everybody!

The FS80 is still apart.. We think its sucking air around the carb to head mount, so I ordered a new gasket.

The new FS85 acts up some, I've tried changing back to Stihl oil, but no difference, it just smokes more.

I hadn't been letting it idle before shut down, I'll start doing that.

The backpack is running good and its still on the amsoil. I'll probably take the FS85 in to the dealer when things slow down. The 85 will not run wide open, it just misses badly.

[65hoss]

New Carb! You more than likely have a vaccum leak in the carb.

[Clewsew]

Also check to see what the proper Oil to fuel mixture is. When you say that the Sthil oil just smokes more, that would be correct if you have gone from 80-1 to 50-1 because you are consuming a higher amount of oil. Look at it as a perc of keeping the Mosquitos away. :D

Khouse may have had good luck with the 100-1 mixture, but I am not sure what his equipment calls for as far as the proper mixture is concerned. Maybe he is really lucky too! If your FS85 is still under warranty, I would not tell them that you ran 80-1 fuel, because then they could say that you are to blame for the problems since you did not follow manufacture specs. Hopefully is is just a prob whit the carb, and you have no engine damage

I am a hugh fan of following what the manufacture recommends for their products. Since they design it or at least sell it, they are not going to tell you to do something that they know is going to cause them more work or support for the future. If your truck holds 5 quarts of oil you wouldn't put 3 in instead right. Anyway Good luck, and I hope you get it fixed.

Clewsew

[Randy J]

This is not a sales pitch for Amsoil, just trying to make sure everyone is on the same page. Amsoil is formulated to be run at a 100:1 ratio, where other oils are at 50:1 ratio. I personally like Amsoil and have no problems with the 100:1 ratio. However, if you're running Stihl oil or something similar, run it at 50:1.
Randy

[Clewsew]

Thanks for the info Randy.

[khouse]

We know it's not the oil anyway because you tried it. Amsoil will pay for any oil related failure.

[Nomoslowmow]

Khouse-

I am a skeptic that Amsoil will EVER replace ANY equipment under this "warrantee". How do you prove that it was an oil related failure-go to court and testify against their lubrication expert witness?

Many people are happy with Amsoil products (I use some of them) but the above replacement promise is just marketing smoke.


Bob

[crawdad]

Did you change the fuel pickup hose? The one in the gas tank? They only last a couple of years.
BTDT
Crawdad

[khouse]

Bob,
I was sceptical also for a manufacturer to say run 100 to 1 when I was running 20 to 32 to 1. Back in 1977 I was an ASE master tech for automobiles and we worked on anything that came in including small engines. One of our customers was an Amsoil dealer and said "hey try this 100 to 1 oil" me and my boss though - what! That will burn up any engine! He said just try it on our own stuff. I remember putting it in my Mom's Lawnboy and pulled the rope. Ran good, so I mowed the yard. Nothing happened except no smoke. I have run it in all my 2 strokes and even run the engine oil in my Honda Oddessy 240 hp. I called Amsoil and said my nephew wanted to run the racing oil in his Yamaha Banshee 350 and he was scared about the warranty. He said if you think it is an oil related problem then he can send papers for a claim. I should have asked more questions on what and how they pay. Maybe you can call and find out for both of us and ask more questions. We can always learn more.
www.amsoil.com