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cjdg

Husqui 550 XP no fuel

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OK, It was  Christmas Eve and I  just could not resist a bit of grafting to finish off a job of chipping and wanted to cut a bit of brash to fit in the chipper and my reliable old 550 XP 2 years old and probably with about 300 hours on it would not start.  Its been good as gold for two years.  It had not been used for about a month, had about 1/3 of the tank full was in the cold so not dried out and it "appears" that the pump is working (but no bubbles).  Pulled my nuts off for up to twenty pulls - no joy.  Took off the plug and it was bone dry - not a drop of fuel. Tried again with lots of pumping - no joy.  I read on this forum that if it gets too hot the fuel vapourises an there is an air lock.  This seems unlikely as it has worked fine for two years.  OK suppose that is right, how do I get fuel to the carb? I was thinking of perhaps putting some in the cylinder and "hoping" that it might drag some liquid in but suspect that is a crazy hope.  How can I tell if the pump bubble is working? There must be a way of disconnecting fuel line to carb and checking.  Yours aye Chris

 

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I think the pump should get to feel firm when you pump it.

 

Is it normal petrol pump fuel? Maybe chuck a bit in the cylinder and see if it will fire up just to rule out the spark, compression etc then concentrate on the feeling side?

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There is a test for the pump on the software and PC interface but not too much help here - they are usually relatively reliable though.

The purge bubble should get fuel in it when it has done its job. It basically hauls fuel through the normal fuel line, through the carb and back in to tank.

If the saw has lost most of its compression or has a major air leak, it can stop the engine pulling fuel through but is unlikely on a 2 year old saw.

These autotunes don't tend to pull loads of fuel through and the plugs don't tend to look that wet even when choke is used many times.

If you are brave, you need to pull the carb off, make sure the fuel line pisses out fuel, then remove the pump cover and check the pump diaphragm, the gauze strainer and that there is fuel in that section. Do the same for the metering section and you will hopefully find where the issue is.

These machines should fire if petrol is put in the plug hole unless the coil is shot - seen one like that!

Most likely issue is shyte in the gauze strainer! .......when I say shyte, I mean wood chip not....you know what:$

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As has been said already the purge pulls fuel from the metering chamber of the carb and dumps back to tank, if the purge is approx 3/4 full there has to be fuel in the metering chamber, this would sort of rule out a blockage in the fuel line or fuel gauze, i would be pulling the clutch, sprocket and oil pump off and checking the crank seal, they are a bit prone to the bearing cage breaking up and ripping the seal out.

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Following on from ADW, the ripped out seal would cause a big air leak and would stop the crankcase making vacuum (when the piston goes upwards) that is needed to pull the fuel and air in to the bottom end.

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On 25/12/2018 at 17:12, Toad said:

I think the pump should get to feel firm when you pump it.

 

Is it normal petrol pump fuel? Maybe chuck a bit in the cylinder and see if it will fire up just to rule out the spark, compression etc then concentrate on the feeling side?

That was my idea as well -works for a motorbike but was not sure of a small cylinder saw.  In fact the fuel bubble is firm and appears to be pumping fuel

 

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On 25/12/2018 at 17:50, Stubby said:

Could be the fuel solenoid .  The primer should feel resistance when full . 

Does not appear to be VERY resistant but then it never did. It is certainly not "easy".

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You should be able to depress the primer bulb with thumb pressure and there should be some fuel in the primer bulb in around 5-10 pushes. Thumb pressure - around 1/3rd of the total thumb pressure you can muster! It isn't difficult!

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