FS 55 RC won't idle

DonnyB

Forum Newbie
Joined
Jun 29, 2016
Threads
3
Messages
8
I have an FS55RC string trimmer that won't idle. It HAD a broken primer bulb, so I ordered a carb kit. That included a new carb (with primer bulb), spark plug, fuel filter, fuel lines, air cleaner, and gaskets. I emptied the fuel and replaced with fresh fuel mix.
In order to start it now, I will prime, set the choke, and crank about 6 or 7 times. I will let it sit for 5 minutes, then prime, choke, and crank. It will start after 2 pulls, but will not idle. I can use it, but I have to run it at almost full throttle and tweaking the throttle (constantly pushing/releasing).
I have tried to adjust the high speed and idle adjustments. Right now the idle is set at about 1.5 turns out from full seat, and the high speed is set at about 1.0 turns out from full seat. No matter how I adjust these, it will not idle.
Anybody have a suggestion?
 

Boobala

Lawn Pro
Joined
Feb 15, 2015
Threads
200
Messages
7,000
Sounds to me as though you MIGHT, have missed something when you were doing your cleaning of the carb. , it's also possible you may have a gasket / seal improperly installed, meticulous cleaning of these small carbs. is very important, for best performance, and attention to proper placement / order of gaskets / seals, is also important, see the following .......
I believe you may have a Zama or Walbro carb. ( you didn't provide make/model of carb info.)

http://outdoorpowerinfo.com/repairs/#id_diaphragm
 

DonnyB

Forum Newbie
Joined
Jun 29, 2016
Threads
3
Messages
8
I used the word "kit" in my description. That was probably a bad choice. The carb is brand new and came with all the other new parts (air cleaner, primer bulb, fuel filter, fuel hoses, spark plug, etc). I don't know the brand of carb, but it did look exactly like the original. I did not do any cleaning or washing of the carb because it was brand new. I read a different post that suggested taking the fuel hose (the one with the filter) off of the carb. Then slowly prime until gas comes out of the open fuel line. If the level drops there might be a bad seal. I did this and the level did not drop. One other thing I thought about was the spark plug gap. I will check that tomorrow, however, if the gap were not right, it would probably not run at all. I did remove the carb one more time to check the gaskets and seals. All seems to be as it should.
Am I on the right track or have I missed something obvious?
BTW, a few months ago, my power washer would barely run and would quit for no reason. I recently replaced that carb/fuel tank and it works like a dream now. I know it's a totally different engine and carb, but it tells me it can be done and that encouraged me to do the same on the FS55RC.
 

Boobala

Lawn Pro
Joined
Feb 15, 2015
Threads
200
Messages
7,000
I used the word "kit" in my description. That was probably a bad choice. The carb is brand new and came with all the other new parts (air cleaner, primer bulb, fuel filter, fuel hoses, spark plug, etc). I don't know the brand of carb, but it did look exactly like the original. I did not do any cleaning or washing of the carb because it was brand new. I read a different post that suggested taking the fuel hose (the one with the filter) off of the carb. Then slowly prime until gas comes out of the open fuel line. If the level drops there might be a bad seal. I did this and the level did not drop. One other thing I thought about was the spark plug gap. I will check that tomorrow, however, if the gap were not right, it would probably not run at all. I did remove the carb one more time to check the gaskets and seals. All seems to be as it should.
Am I on the right track or have I missed something obvious?
BTW, a few months ago, my power washer would barely run and would quit for no reason. I recently replaced that carb/fuel tank and it works like a dream now. I know it's a totally different engine and carb, but it tells me it can be done and that encouraged me to do the same on the FS55RC.

Without trying to "rain on your parade" .. sometimes even a new carb is bad, also have you pulled the muffler off to check for heavy carbon and cleaned it too ?? Not using too much oil in your fuel mix , are you ?? I live near Ocala, Fl. .. Where are you located ..?? (city) ?? I'll do some diiging and see if I can find something else in my files, off-hand, with ALL new parts being clean and such, I'm head scratchin !!
 

EngineMan

Lawn Addict
Joined
Jun 12, 2012
Threads
9
Messages
2,275
When you replaced the gasket did you put it the right way round (hole in the gasket see photo), and have you done a leakage test yet.
 

Attachments

  • stihlfs55carb copy.jpg
    stihlfs55carb copy.jpg
    69.1 KB · Views: 15

DonnyB

Forum Newbie
Joined
Jun 29, 2016
Threads
3
Messages
8
In answer to the questions raised, I did a leak test. By leak test, I mean I removed the fuel line from the carb - the one hooked to the fuel filter. Then I slowly primed it until gas came to the surface of the exposed fuel line. The level did not go down for about 5 minutes. One thing I will check later today is the spark plug gap. Also, someone suggested the Ebay carbs are not all that reliable and could be the cause of my problems. I have the old carb and the only problem it had was a cracked primer bulb. I am going to try putting the good bulb on the old carb and see if that helps. Since I just retired, I have lots of time for things like this, but this one project has consumed a lot of time already.
I did remove the spark arrestor and cleaned it, although it was not that dirty.
I live in Apopka going on about 3 years now. I was afraid this forum would not be very active since it is winter time. Those of us living in Florida need lawn care all year long.
I am scratching my head also. I will do the things I mentioned and see what happens.
 

BlazNT

Lawn Pro
Joined
Apr 26, 2012
Threads
28
Messages
6,973
The line connected to the fuel filter is the fuel inlet. You have the fuel lines crossed. That may be the problem.
 

DonnyB

Forum Newbie
Joined
Jun 29, 2016
Threads
3
Messages
8
I think I have found the problem. I removed the carb one more time, and thanks to EngineMan, I looked at the gasket with the small hole in the bottom. There was a fragment from the old gasket that was covering the small hole. I cleaned that off and put it all back together. It now starts easily and will idle just fine. Thanks to all for your help!
 

EngineMan

Lawn Addict
Joined
Jun 12, 2012
Threads
9
Messages
2,275
Set (H) 3/4 turn out and (L) 1 turn out that's if you haven't already done so. and thanks for the feedback.
 

Boobala

Lawn Pro
Joined
Feb 15, 2015
Threads
200
Messages
7,000
Don't be a stranger Donny ! Glad it's up & running, .. Happy New Year ..!!!
 
Top