saw suddenly won't start

[travis]

Chaps and Chapesses,

my Husqvarna, after working perfectly the day before, now won't start. The saw won't even pop on full-choke.

i have checked a few things; there is a spark, the chamber isn't scored, tried different plugs, compression i would say is pretty good. as for fuel, freshly mixed.

what could be the problem ? working great one day, won't cough the next ?

 

thanks in advance

travis

[Stubby]

Chaps and Chapesses,

my Husqvarna, after working perfectly the day before, now won't start. The saw won't even pop on full-choke.

i have checked a few things; there is a spark, the chamber isn't scored, tried different plugs, compression i would say is pretty good. as for fuel, freshly mixed.

what could be the problem ? working great one day, won't cough the next ?

 

thanks in advance

travis

 

If all of the above is true then fuel starvation for some reason . Is the plug wet after you try to start it it ?

[Brushcutter]

Is it a 550 or 560

[spudulike]

In very basic terms, a working engine needs Compression, spark and fuel - if the piston isn't scored and the saw isn't that old then make sure the plug is wet after a few pulls on full choke, it is possible the metering arm isn't high enough causing fuelling issues!

[travis]

brushcutter, the saw is the 575xp.

spud, yes the plug is wet, fuel was filling the exhaust because i pulled the starter so much.

what is the metering arm ?

do these saws suffer from the perished carb diaphragm ? and could that be a problem ?

[spudulike]

brushcutter, the saw is the 575xp.

spud, yes the plug is wet, fuel was filling the exhaust because i pulled the starter so much.

what is the metering arm ?

do these saws suffer from the perished carb diaphragm ? and could that be a problem ?

 

Right, assuming you checked the piston by taking off the exhaust, You need to clear all that puddled fuel -

 

Take the plug out, turn the saw upside down and pull it over hard a few times with the ignition turned off!

 

Heat the spark plug so it is good and hot - a plumbers lamp or gas hob is good for this.

 

Stick it back in the saw and pull the choke out and push it back in so the fast idle is on and give it a damn good pull with the decomp out, it will generally fire or try to.

 

If it doesnt work, try putting the choke on and then pushing it off and see if the fast idle makes a light click when coming off when you open the throttle - it should.

 

If you have that much fuel in the exhaust, the metering arm isn't at fault - it may possibly be the needle valve leaking though!

[elliott EGD]

Did you keep trying to pull it over sounds like just a bad case of flooding keep the plug out and let it dry out a bit try again tomorrow

[travis]

elliot, yes i did pull it over and over. decided that i had flooded it. that was friday though and it still won't start. argh.

Spud, i did remove the exhaust and tried to tip out as much fuel that was swishing round.

now that you mention the full-choke to fast idle 'click' i don't remember hearing it, is that important ?

what happens when the needle valve is leaking ?

[spudulike]

When you pull the choke on, two things happen, the choke flap is closed and also the throttle valve is kicked open a little to give fast idle. If the mechanism isnt holding the throttle open when the choke is pushed in then this can make a saw a bitch to start. Generally the mechanism clicks when it comes off when opening the throttle.

 

The needle valve stops the contents of the fuel tank flowing in to the carb. If it is leaking, you get flooding of the saw even when not trying to start it - you generally find fuel flowing out of the carb and in to the inlet manifild and engine.

 

An exhaust full of fuel makes me thing you have severly flooded the engine - probably from pulling it over too much on choke - clear the puddled fuel as I have described and try it again - if it won't pop after 5-8 pulls with the choke on then any more will flood the engine as has happened with your previous attempts:thumbdown:

[GardenKit]

The thing with a flooded 2stroke is that it does not just dry out like a 4stroke

Sure, the fuel in the combustion chamber evaporates slowly, but it leaves behind an oil residue.

 

So you clean the plug and blow out the pot, but then you pull it over again and it pulls through more petrol from the flooded crankcase. This is very rich in oil too, so it oils the plug straight up. You may need to clean the plug several times.

 

These things can stay flooded for days after the first failed start.

 

Keep the choke off, open the throttle and keep pulling for all you are worth. Eventually it will cough once, then twice, then three times. Then it might run and chuck out clouds of smoke.

 

Keep it going until the exhaust is clear and the engine note is sweet.