work this out.

[jimllshiftit]

right then,

i have a stihl fs76 trimmer that does not work. it will start and run for a few minutes then lose power and die.

good bits are:

new diaframs in the carb,
new fuel filter,
new piston rings,
new base gasket,
checked the fuel lines,
compression is good,
spark plug is dry whem removed after its cut out,
new plug doesnt help it,
spark is still strong when the machine has cut out,
tank cap is clear,

bad bits are:

worn butterfly in the carb,
some vertical scoring on the piston and the barrel,
evidence that the piston has seized at some point in the past,
evidence of overheating,

the bad bits may provide some clue as to what is causing it to fail although all those problems were present when the machine was working fine.

i cant figure it out - can you?

 

[MJR]

Buy a second unit and use yours for parts. Good luck.


Grass Trimmer- Stihl FS 76 Gas Powered - $250
________________________________________
Reply to: [email protected]
Date: 2007-07-18, 3:10PM PDT


This is a great grass trimmer. It has been used very little. If you have tall grass, this is what you want. These sell for over $400. Call Tom or Pam 541-385-7770





• Location: awbrey butte
• it's NOT ok to contact this poster with services or other commercial interests

PostingID: 376903903

 

[FJH]

right then,

i have a stihl fs76 trimmer that does not work. it will start and run for a few minutes then lose power and die.

good bits are:

new diaframs in the carb,
new fuel filter,
new piston rings,
new base gasket,
checked the fuel lines,
compression is good,
spark plug is dry whem removed after its cut out,
new plug doesnt help it,
spark is still strong when the machine has cut out,
tank cap is clear,

bad bits are:

worn butterfly in the carb,
some vertical scoring on the piston and the barrel,
evidence that the piston has seized at some point in the past,
evidence of overheating,

the bad bits may provide some clue as to what is causing it to fail although all those problems were present when the machine was working fine.

i cant figure it out - can you?

>some vertical scoring on the piston and the barrel,
evidence that the piston has seized at some point in the past,
evidence of overheating, <

There is a good chance that this is causeing your problem as the fuelpump needs a good seal on the piston and rings to work properly!scoring is usualy caused by too lean of a mix or not enough oil in the gas!

 

[2506]

pin hole ?

My Husky pole saw exhibited the same behavior. Took a while, but I traced it down to a tiny pin hole in the fuel line. It would run for a very short time, then lean out and die. Works good as new with new fuel line.

 

[jimllshiftit]

>some vertical scoring on the piston and the barrel,
evidence that the piston has seized at some point in the past,
evidence of overheating, <

There is a good chance that this is causeing your problem as the fuelpump needs a good seal on the piston and rings to work properly!scoring is usualy caused by too lean of a mix or not enough oil in the gas!

im sure you are right but at £125 for a new barrel and piston i want to make sure that it cant be anything more simple.

is there any way to ensure that the diaphragm is set up properly?

i use a 28 / 1 fuel mix but i dont know what the previous owner used and it must have seized during that ownership. what mix do the pro's use?

 

[mysawmyrules]

I'm no small engine expert a diesel is more my speed but I did have the same problem with both of ours a fs 80 and a fs 38 and I immediately over engineered my problem and it turned out to be on the fs 80 a piece of carbon dancing around and restricting the muffler and the fs 38 was the screen holes were just carboned enough to make it flutter and then power out. Might not be the trouble but the symptoms sound the same and the propane torch to burn out the carbon is cheap.

 

[FJH]

im sure you are right but at £125 for a new barrel and piston i want to make sure that it cant be anything more simple.

is there any way to ensure that the diaphragm is set up properly?

i use a 28 / 1 fuel mix but i dont know what the previous owner used and it must have seized during that ownership. what mix do the pro's use?

Thats a stout mix for that. I use a 20 to one on my mill saw cause its working hard I Wouldn't use that on on a michine like yours 30 35 to 1 is ample.My Mill saw once into a log cleans right up and burns every bit of the oil cleanly no smoke just diggs in and goes!