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Stihl FS-51AVE Won't Start


rossiskiracer91's Avatar
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07-14-10, 11:17 AM   #1  
Stihl FS-51AVE Won't Start

After a winter of sitting in a shed at my cottage, my Stihl weed eater wont start. I got a new spark plug and changed the fuel. Nothing seems to work. Any ideas of what I can do? I had stabil in the gas over the winter also.

 
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07-14-10, 02:26 PM   #2  
does it have spark? is the plug getting wet?

 
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07-14-10, 07:56 PM   #3  
There is spark and the plug is wet. I checked the gap too and its correct

 
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07-15-10, 02:02 AM   #4  
good one...is there anything blocking the muffler? air filter?

 
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07-15-10, 05:24 AM   #5  
Nothing is blocking the muffler and the air filter is pretty much disentegrated.

 
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07-19-10, 07:55 AM   #6  
how old is the unit? does it have good compression? with low compression it will be hard to start if at all. take out plug and hold your thumb over the plug hole and give it a good pull, you should not be able to hold back the pressure, or use a tester if you have one available.

 
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09-06-10, 10:05 PM   #7  
Model FS51ave won't start

Hi, and my first post.
I have the same model, & it too won't start after sitting two summers. It's always been quite faithful in the past.

I set it on 2 jack stands on the bench, disconnected the fuel line from carb with a full tank of fuel,
turned on the fuel valve, and no fuel flows.

*On the bottom of carb, there is a vacuum fuel pump diaphragm that controls needle & seat similar to typical float bowl.
It's possible this diaphragm went bad, but good chance it's Ok.

I disassembled fuel line to tank, and it's quite a complex arrangement of fittings.

Loosen main clamp that holds the rubber flanged adaptor to tank.
Slide this adaptor off, and you will see the small rubber fuel line.

*This is a good time to set a square cake pan under the unit to catch remaining fuel that will drain out once this rubber adaptor is removed from tank.

Carefully remove small rubber line going into fuel tank that's fitted on stem of fuel valve, and set valve aside.

Now to get swinging fuel pickup out of fuel tank that's on the other end of this fuel line.
It has to come out the fuel cap opening.

This swinging fuel pickup has filter media locked on this weighted bobber, so it has to be cleaned using can of contact/brake cleaner with spray tube fitted to blow into small end of hose to back-flush filter.

I set this assembly in the cake pan while using the cleaner.
Good rubber gloves help.
Make sure space is safe from and sparks.
Don't set trouble light near if it drops.
I use light-stand that sits on the floor.

I would not use air hose to blow through this small fuel line, unless you have a regulated line pressure installed to go gently about 10psi.
The small fuel line hose would easily burst.

The fuel line from valve to carb may be very hard and brittle, so I replaced it with 1/8" Tygon fuel line that you can see through.
Hobby stores stock it.

I now have to solve why there is no spark, otherwise it would be running.
The coil is mounted in cover after the drive stem is removed from power head.

If you come across manual to cover the service, that would be great.

Cheers & good luck

 
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