FS 55 not priming

jm123

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According to Manuel the Mexican Mechanic the two needles are set to 3 turns out each so give them another turn and try again.

Also try starting with the trigger pulled in and the idle wound up full
Adjust the high speed jet first, lean ( in ) till it starts to faulter then rich ( out) till it starts to faulter then slightly to the rich side of 1/2 way between them.
Make sure there is a foot of line hanging out of the head to put a bit of load on the engine.
now let your finger off the throttle slowly.
You should be able to get it to stay running as with the idle ( throttle stop ) screwed all the way in it should be running on both the high & low speed jets.
Start backing the throttle stop ( TS) out till the engine slows then adjust the Low jet to the fastest running position then back off the TS some more.
Continue till the head just stops spinning then do the same adjustment with the low jet as done with the high.
If the head starts to spin, back off the TS a little more.
When the Idle Jet is correct you will get a smooth acceleration.
If it speeds up a bit then drops back as you throttle on the Low is a little too lean.
If it bogs down as you throttle on the Low is a little too rich.

Thanks! I'll try this tomorrow. Today actually. Reading a book.
 

jm123

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Success! Well sort of.

I followed the instructions above and got it started. Let it run for a while to do some tuning. Got it tuned so that it wasn't too rough, head not spinning at idle. Used the trimmer to clear some brush. Seemed a bit under powered.

That was when I noticed that I'd forgotten to open the choke. Oopsie. So I opened the choke and it stopped running. Needed to put more line in anyway.

Should get it working tomorrow.
 

bertsmobile1

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If it ran with the choke out you are about 1 turn too lean.
You would not be the first person to tune the carb with the choke on.
There is a reason why I know you are about 1 turn too lean :ashamed:
 

jm123

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Re: FS 55 not priming [Solved]

If it ran with the choke out you are about 1 turn too lean.
You would not be the first person to tune the carb with the choke on.
There is a reason why I know you are about 1 turn too lean :ashamed:

Victory at last!

Reset the three screws to all the way in. Backed High, Low out three turns. Fiddled with them (small adjustments) until the trimmer started. Let it warm up, added some gas to get about half a tank. Tuned it until it sounded good, accelerated well.

Mowed some brush. Finally ran it out of string. Was low enough on gas that it stopped when turned on its side.

Scraped off grass debris until the head cooled down(after noticing that it was *hot*). Put in new line, filled the tank. Started using normal procedure on second pull.

Some other thoughts:

- If you get an aftermarket carb the H and L screws may not be labelled. They aren't on mine. The left is High. The black knob is quite a bit larger as well.
- Once it's running small adjustments work a lot better. Keep the screwdriver in place in case you go too far. Patience...


I want to thank everyone who helped!
 
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