HS45 runnning problems

[Jwc]

hi all ive got a stihl hs45 its possibly only 18 months old and had minimal use but recently went to use it and it just wont run. can start it after 10 ish pulls on choke then it dies, sometimes i can then take the choke off and it will start then just cut out straight away. Ive stripped the carb right down replaced all the gaskets etc cleaned the carb with carb cleaner and still nothing. someone once mentioned spark arrestor and muffler needing cleaning but mines a sealed unit it just has one hole that goes onto the exhaust outlet and another piper thats the exhaust nothing else comes off it. completely stuck as what to do with it now and i need it. The carb looks mint inside, there was no dirt of markings at all. cleaned the spark plug check for a spark of that and it sparks perfect?

 

any help will be greatly received and appreciated.

 

many thanks

[felixthelogchopper]

Will it start again if you undo the filler cap then replace it?

[base]

I had a HS45, the fuel pipe was sucking / collasping together when underload, on tickover it was fine but underload would cut out, never came across this before took along time to find the problem. I was convinced it was a carb problem and had the carb apart alot:)

[Jwc]

just had a try and it started and ran but not well enough to use with the fuel cap off/loose but did cut out in the end, now it wont start again.

 

how did you find out the fuel line was collapsing could you see the green pipe squeezing together?

[slim reaper]

When you cleaned the carb did you take out the mixture adjusting screws inlet needle and wire gauze filter ?

[Jwc]

When you cleaned the carb did you take out the mixture adjusting screws inlet needle and wire gauze filter ?

 

Yea it's stripped right down and cleaned with carb cleaner and then replaced.

[harrythecat178]

Try another carb off a known good machine

[spudulike]

Sounds like lack of fuel as ten pulls is a lot on full choke.

 

Check the thin plastic pump diaphragm is against the main body of the carb and the spacer gasket is between the pump diaphragm and the cover.

 

Check the fuel line isn't split and the filter is in good shape.

 

Check the gauze strainer is clear, they often get a fine clear haze of scum in them that looks fine but stops fuel and you need to remove it and view with a magnifying glass to see it.

 

Other than that, check the spacer gasket is between the metering diaphragm and the body of the carb and the metering arm is set high enough and the spring is set correctly.