Runs ok--for 3 seconds


  #1  
Old 05-25-18, 12:06 PM
T
Member
Thread Starter
Join Date: Apr 2011
Location: USa
Posts: 142
Received 1 Upvote on 1 Post
Runs ok--for 3 seconds

My Stihl FS-76 string trimmer ran fine yesterday. Now suddenly it will start and run for a few seconds, then dies. Then I can immediately start it again--same story. Just a few seconds, over & over; choke or no choke. Giving it gas tends to kill it. I tried removing the fuel filter & air filter; no difference. Time to get the carb cleaned, or is there something else I should try?
 
  #2  
Old 05-25-18, 03:32 PM
A
Member
Join Date: Jan 2013
Location: U.S.A.
Posts: 1,902
Received 73 Upvotes on 66 Posts
I'm sure others here have better replies, but I'd start by cleaning the gas cap. Although it generally takes longer with a larger engine, I've seen this happen with lawn mowers and such, and it only stands to reason that a vacuum in the tank is going to arise sooner with a smaller engine. If not that, I would go with a carb overhaul or replacement. I can't think which one it was a couple years ago, but a replacement carb for something I was working on was within a few bucks of a kit.
 
  #3  
Old 05-25-18, 03:37 PM
J
Member
Join Date: Jan 2011
Location: USA
Posts: 4,459
Received 125 Upvotes on 110 Posts
A total replacement carb is by far the fastest easiest way to fix it.
There's so many tiny parts and orifices it's a real pain to try and rebuild one.
 
  #4  
Old 05-25-18, 05:05 PM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 4,960
Received 158 Upvotes on 144 Posts
Have you checked the spark plug?
Geo
 
  #5  
Old 05-25-18, 08:35 PM
cheese's Avatar
Forum Topic Moderator
Join Date: Jul 2001
Location: USA
Posts: 15,797
Received 112 Upvotes on 102 Posts
I agree with just replacing the carb. They are so cheap these days that it isn't worth trying to rebuild it and possibly end up having to replace it anyway.
 
  #6  
Old 05-27-18, 12:30 PM
T
Member
Thread Starter
Join Date: Apr 2011
Location: USa
Posts: 142
Received 1 Upvote on 1 Post
Wow--Just for the heck of it, before replacing the carb, I cleaned it w/ spray carb cleaner. That miraculously cured it! (this time...)
 
  #7  
Old 05-27-18, 12:37 PM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 4,960
Received 158 Upvotes on 144 Posts
Hi, run some Seafoam through it to clean the whole fuel system out.
Geo
 
  #8  
Old 05-27-18, 01:12 PM
T
Member
Thread Starter
Join Date: Apr 2011
Location: USa
Posts: 142
Received 1 Upvote on 1 Post
I had tried some other carb cleaner of the type you dump in the tank; then repeatedly, about 30 times, started it; waited for it to die after a few seconds; started it again...

The carb cleaner that you spray into the carb worked a whole lot better. But did not try Seafoam. Does it seem to be better than other carb cleaners that you mix w/ the gas?
 
  #9  
Old 05-27-18, 02:49 PM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 4,960
Received 158 Upvotes on 144 Posts
I have had good luck with it, itís a bit expensive but have you to loose?
Geo
 
  #10  
Old 05-27-18, 03:05 PM
BFHFixit's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jun 2007
Location: USA.
Posts: 1,511
Upvotes: 0
Received 0 Upvotes on 0 Posts
Seafoam does not nor claim to do anything for diaphragm carburetor's. It will not rejuvenate diaphragms and gaskets.
As already mentioned I agree to replace the carb and fuel lines.
 
  #11  
Old 05-27-18, 05:39 PM
2
Member
Join Date: Jan 2014
Location: USA
Posts: 29
Received 2 Upvotes on 2 Posts
Taking off the carb and cleaning thoroughly should cure the problem and order a rebuild kit and replace your rubber parts and gasket every season. I'm betting your using 10% ethanol fuel. What happens is when the trimmer cools down and condensation forms (no matter how little), the ethanol separates from the gas and binds to the water molecules and forms a varnish. This is why gas won't keep for more than a couple of months anymore, especially in a garage or storage shed where temperatures fluctuate quite a bit. To help combat the problem of crappy gas, get yourself a 2 quart mixing cup and use a MixMizer and only mix a 1/2 pint to a pint at a time.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: