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Need ideas on FS 111RX poor running engine

#1

M

MagnumMike

Hi guys! I have a one year old trimmer that has problems producing full power. Since new, the machine starts fine but only seems to reach half throttle, regardless of how much I squeeze the trigger. The machine has less than 10 hours on it (I keep track). I only use non ethanol fuel along with Stihl HP Ultra 2 stroke oil. From idle to half throttle is normal. After that it won't rev up any higher. Recently during a 90* day in upstate NY, I could not keep it running. I needed to continually "play" with the throttle just to prevent it from stalling. Releasing the throttle caused it to die immediately. It continued to start on first pull, but would not stay running without playing with the throttle. Seemed like it was starving for fuel. Before storing last winter, I ran Stabil 360 through engine and then drained fuel tank. Dealer suggested rebuilding the carb with a new kit. That doesn't make sense to me, given it is 11 months old with less that 10 hours on the engine. Any thoughts on this issue are greatly appreciated!!

Thanks in advance!

Mike


#2

M

mechanic mark

Absolutely, I use 93 octane gasoline with fuel additive Star Tron in 5 gal. gas can per instructions on bottle in all outdoor power equipment.
www.lawnmowerforum.com

Fuel - John Deere Fuel Treatment

https://www.google.com/search?q=john+deere+fuel+treatment&oq=john+deere+fuel+treatment&aqs=chrome..69i57j0j69i60l2j69i61.19212j0j4&sourceid=chrome&ie=UTF-8
www.lawnmowerforum.com www.lawnmowerforum.com
Read page 18 concerning ethanol & unleaded, paragraph 4 is why I choose to use 93 octane gasoline.


#3

Fish

Fish

Taqke a look at the screen in the muffler. It could be carboned up too much, and giving you problems.
Like a potato in your tailpipe...
$_57.jpg


#4

Fish

Fish

If it is,
look at your air filter.


#5

S

slomo

With only 10 hours on a new engine, you might have your fuel mix messed up. If you remove the muffler and the window (spark arrestor) screen is plugged with carbon, your mix is waaay off. I would take it back to the dealer and make them fix it under warranty. Course they are going to tell you that you used the wrong octane and too much oil, blaming you. Then politely ask them when will it be fixed.

Make sure you SHAKE/SWIRL your fuel can every time before filling. I've seen boats where guys dump oil in the tank and it never mixes. One boat was half full of oil sitting on the bottom of the tank. Guy was complaining about fuel range LOL.

Make sure the throttle trigger is giving you full throttle AT the carb. Throttle cable routing might need looked at.

Sure sounds like a plugged exhaust.

When you put the 360 in, did you shake the can?

slomo


#6

Fish

Fish

Then again, I missed the "since new", and "only 10 hours" parts.
Likely the gas is bad by now, and should be replaced.
But you must realize that these four stroke trimmers run a whole lot slower, but have much more "grunt".


#7

M

MagnumMike

Fish said:
Then again, I missed the "since new", and "only 10 hours" parts.
Likely the gas is bad by now, and should be replaced.
But you must realize that these four stroke trimmers run a whole lot slower, but have much more "grunt".
Click to expand...


#8

M

MagnumMike

MagnumMike said:
Hi guys! I have a one year old trimmer that has problems producing full power. Since new, the machine starts fine but only seems to reach half throttle, regardless of how much I squeeze the trigger. The machine has less than 10 hours on it (I keep track). I only use non ethanol fuel along with Stihl HP Ultra 2 stroke oil. From idle to half throttle is normal. After that it won't rev up any higher. Recently during a 90* day in upstate NY, I could not keep it running. I needed to continually "play" with the throttle just to prevent it from stalling. Releasing the throttle caused it to die immediately. It continued to start on first pull, but would not stay running without playing with the throttle. Seemed like it was starving for fuel. Before storing last winter, I ran Stabil 360 through engine and then drained fuel tank. Dealer suggested rebuilding the carb with a new kit. That doesn't make sense to me, given it is 11 months old with less that 10 hours on the engine. Any thoughts on this issue are greatly appreciated!!

Thanks in advance!

Mike
Click to expand...
slomo said:
With only 10 hours on a new engine, you might have your fuel mix messed up. If you remove the muffler and the window (spark arrestor) screen is plugged with carbon, your mix is waaay off. I would take it back to the dealer and make them fix it under warranty. Course they are going to tell you that you used the wrong octane and too much oil, blaming you. Then politely ask them when will it be fixed.

Make sure you SHAKE/SWIRL your fuel can every time before filling. I've seen boats where guys dump oil in the tank and it never mixes. One boat was half full of oil sitting on the bottom of the tank. Guy was complaining about fuel range LOL.

Make sure the throttle trigger is giving you full throttle AT the carb. Throttle cable routing might need looked at.

Sure sounds like a plugged exhaust.

When you put the 360 in, did you shake the can?

slomo
Click to expand...


#9

M

MagnumMike

Thanks for the quick reply! To clarify, I'm using Sunoco 90 Non-Ethanol with the Stihl Oil. The mix is fine as I'm using the same fuel/oil mix in my leaf blower and chain saw with no issues. The lack of power issue start with the very first tank of fuel. I did not keep any fuel in the machine over the winter. After emptying the tank, I ran the engine till it quit. I will check the spark arrestor, but can they clog up after such a short period of time? Previously I had a John Deere trimmer that the arrestor plugged up after 10+ years of use.


#10

Fish

Fish

Can you put up a video of it running?


#11

M

MagnumMike

Taking it to dealer today. Took off the plastic shroud and muffler screen. Filter is like new as is the muffler screen. Fuel/Oil mix is used in other machines with no problem. Appreciate your thoughts!!!


#12

S

slomo

MagnumMike said:
Taking it to dealer today. Took off the plastic shroud and muffler screen. Filter is like new as is the muffler screen. Fuel/Oil mix is used in other machines with no problem. Appreciate your thoughts!!!
Click to expand...
Poor running is either a dirty carb, stale gas or plugged exhaust. You said muffler spark arrestor screen was clean. Only leaves carb or stale gas. What does fresh gas and oil do for it?

slomo


#13

M

MagnumMike

slomo said:
Poor running is either a dirty carb, stale gas or plugged exhaust. You said muffler spark arrestor screen was clean. Only leaves carb or stale gas. What does fresh gas and oil do for it?

slomo
Click to expand...
I'm using fresh gas. My other machines are running fine on the same fuel/oil source. If it is a dirty carb, I'm trying to understand how that can happen with less than 10 hrs on engine. It has been properly (per the manual) winterized during off season.


#14

Hammermechanicman

Hammermechanicman

How did you store the unit over the winter? Full of premix fuel? Run till empty and just quits? Run till empty and when start stumbling and close choke and run till quits with choke on and the pull rope numerous times with choke closed to be sure all fuel is out of carb? I work on equipment every year where people "ran it empty" where they let it run till it just stops and putting it up and the carb needs serviced next season. Filling it with mix and leaving it over the winter can be a problem too, depending. Being a 4mix engine first thing is the check and adjust the valves then troubleshoot fuel issues.


#15

S

slomo

MagnumMike said:
I'm using fresh gas. My other machines are running fine on the same fuel/oil source. If it is a dirty carb, I'm trying to understand how that can happen with less than 10 hrs on engine. It has been properly (per the manual) winterized during off season.
Click to expand...
That removes the fresh gas issue. Now you are back to a dirty carb or cracked fuel lines. Might have a vacuum leak at the carb area. Forget about winterizing. That means nothing now.

Was this machine used to cut down farmers fields and fence lines? Overgrown yards? Some how dirt/grit is inside the carb and won't run properly. Fuel filter okay?

Get a carb rebuild kit. Take it all apart. Remove all plastic and rubber parts, set aside. Place the carb in the wife's dishwasher on pot scrubber super mode. Next dunk the metal parts in pure ammonia for a day or so. Blow it out with a real air compressor and air nozzle both ways. Soak again in ammonia if needed and blow. Install new carb kit and test.

Do you have strong spark and a good plug?

slomo


#16

M

MagnumMike

Hammermechanicman said:
How did you store the unit over the winter? Full of premix fuel? Run till empty and just quits? Run till empty and when start stumbling and close choke and run till quits with choke on and the pull rope numerous times with choke closed to be sure all fuel is out of carb? I work on equipment every year where people "ran it empty" where they let it run till it just stops and putting it up and the carb needs serviced next season. Filling it with mix and leaving it over the winter can be a problem too, depending. Being a 4mix engine first thing is the check and adjust the valves then troubleshoot fuel issues.
Click to expand...
Thanks for the feedback Hammer! What's strange is this particular machine has had the lack of power issue from the day I bought. It always starts on first or second pull. Even during the latest episode where it did not want to run, it restarted on the 1st pull after it died. I own 4 motorcycles, 2 JD tractors and a new Ferris Z-Turn. I am a fanatic when it comes to maintenance. Luckily this is still under warranty so the dealer will be addressing the problem.


#17

S

slomo

MagnumMike said:
Thanks for the feedback Hammer! What's strange is this particular machine has had the lack of power issue from the day I bought. It always starts on first or second pull. Even during the latest episode where it did not want to run, it restarted on the 1st pull after it died. I own 4 motorcycles, 2 JD tractors and a new Ferris Z-Turn. I am a fanatic when it comes to maintenance. Luckily this is still under warranty so the dealer will be addressing the problem.
Click to expand...
Why didn't you say it's under warranty from the start? It never ran proper from day 1.

slomo


#18

M

MagnumMike

slomo said:
Why didn't you say it's under warranty from the start? It never ran proper from day 1.

slomo
Click to expand...
I noted in my initial post that the unit would not rev up to full rpm. Regardless of whether it was under warranty, I wanted to understand why it was running that poorly for a new machine. That's what I thought this forum was for. Sorry if I was mistaken.


#19

S

slomo

MagnumMike said:
I noted in my initial post that the unit would not rev up to full rpm. Regardless of whether it was under warranty, I wanted to understand why it was running that poorly for a new machine. That's what I thought this forum was for. Sorry if I was mistaken.
Click to expand...
No problem but you kinda of took up our non-precious time with your warranty claim. This is not a new machine. It is used. Good luck with it.

slomo


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