hello jon,
sounds like your exaust could be pluged. been useing stihl oil mix? if you don't the exaust will plug up.also aircooled engines need to be run wide open this will burn off carbon deposites so they won't buil up
pull the exaust screen out of the muffler and throw it away it should run fine then

 

Check that all the wiring is in place in the handle.

 

I agree

Also take the actual muffler off and turn it where the port is facing down and scrape the buildup from the exhaust port

FS45 is a homeowner model and that could be part of the problem

 

I took the exhaust off, but i dont no what you mean by takng the screen out. There was no carbon build up in the exhaust. even when i started it without the exhaust, it still had the same problem.
The electrics seem o.k,
i think there is too much fuel getting to it, coz when you touch the throttle, it sprays loads.
what shall i do now
thanks
jon

 

What type carb is on that model (the box one- or the one with a cable going in the top?) sounds like a good adjust might help (maybe replacing the diaphrams too).

 

try this there are two adj. screws on carb. one marked H the other marked L turn the one marked L anti-clockwise a little 1/8 or 1/4 turn and see if this helps

 

DO NOT TRY TO ADJUST THIS CARB!!!!
it has no adjustment screws and if it does they will have caps on them all you will do is ruin it take it to your dealer or buy a new one they are on sale now for $139.00 with a ten dollar rebate so it will only cost you 129.00 plus tax

 

had the same exact problem not to long ago on the same hedge trimmer. tried to give it gas and it started to 'bog' down and would eventually die.

the 'spark' arrestor screen has to be unscrewed from the muffler..once it it unscrewed, the problem should be solved...

talked to the dealer not long ago and the 'spark' arrestor screen shouldn't be a problem if you're using the correct gas/oil ratio. but it doesn't void the warranty if you take it off or anything...

let us know if that's the problem...

dave

 

Change the fuel line. 99% sure it is cracked somewhere.

 

A few stihl's died this season. One was a scored piston(at the exhaust port) and two wore out with no compression(always check before checking for spark with your finger over the muffler hole). If there is gas or dirt stuck to gas around the carb you might just get away with tightening every screw you can see( except the mixture screws). If that doesn't work, you can try opening the carb and cleaning out the little fuel screen and jets. You also might end up having to get a carb kit with all the sealing parts.