Husqvarna 460 Rancher fuel breather problem

[pleasant]

24 minutes ago, adw said:

Will everybody stop calling it a bloody primer, it’s a purge!

A fair point adw....admittedly in this case it should be referred to as a purge bulb, although this is not a correct name for all applications and type. All depends on the age of the machine and purpose. Modern machines generally use a purge primer to 'purge' the system of air prior to starting....they do not inject fuel into the carb. Unlike earlier systems (and some still used today....predominantly on 4 strokes) whereby the correct term is a primer bulb, which primes the system by injecting fuel mix into the carb to aid cold starting.

 

Edited February 13, 2023 by pleasant

[JohnBoyy]

So now that I actually know what way the fuel flows I didn't like the fuel supply hose, it was twisted and a little kinked.  I shot a bit of wd40 on the bush it passes through and pulled it up and down a bit and got it sitting happier.

 

Cleaned the filter with carb cleaner even though it looked pretty spotless.

 

Popped the plug which was what I thought was a fairly nice shade of beige.

 

I've it all back together and will test tomorrow and report back.

 

 

[adw]

18 minutes ago, pleasant said:

 

 Noted.

[openspaceman]

 All the bulbs I have come across on hand held two stroke motors have been to purge, i.e they pull fresh fuel through the carb and dump any vapour, air or hot fuel back to tank.

 

On old B&S mowers with float less carburetors there is a bulb which squirts petrol directly into the choke tube as there is no choke control.

 

We had a similar device on old motorbikes, a "tickler" which depressed the float and allowed fuel to dribble up the main jet into the choke tube, recipe for flooding if used on a warm engine.

[Muddy42]

Let us know if straightening the kink and cleaning everything fixes it. As I said the new one might also be defective. I assume you’ve tried sucking carb cleaner or petrol through the tank breather with your pump? Or poking it with a pin?

[JohnBoyy]

Took it for a test drive at lunch time.  I don't have much big timber here but I ran it as hard as I could for 15 minutes.  It spluttered once or twice but never died.

 

if it was running 40% right before it was definitely 80-90% now.

 

 

I'm now wondering did I manage to accidentally reinstall the blocked original breather rather than the new one the day I bought the new one to replace the leaky spurious one.

 

Assuming saturday comes dry I'll be on the farm where I have a lot of ash down and I'll report back.

[JohnBoyy]

No joy I'm afraid.

 

Once I got it into some sustained cutting at the weekend it started its usual tricks dieing a death on me.

 

I swapped back in the spurious vent and no dieing issues, but I did have a few hot start problems then, which this saw never ever has, it's always unreal to start, max 3 pulls cold and always starts on the first pull when hot, so there's definitely something else up, also I felt on saturday that the purge bulb wasnt filling like it normally would  That could be down to me taking the hoses on and off half a dozen times during the week too I guess.

 

Fuel filter and hoses are probably a good idea, what else after that?  strip and clean the carb?  looks a more complex beast than carbs I've worked on before, but sure every day's a schoolday.

[Muddy42]

How annoying.  If it has one, have you checked the spark arrester screen is clean in the muffler?

 

I think it would be helpful for you to disassemble the fuel tank half of the saw completely, to help with the diagnosis and testing.  There are plenty of youtube videos if you google "rebuild husqvarna chainsaw" or something.  Just take your time, have a large clear bench so you can put each part aside with its screws (or keep the screws in the holes).

 

Once the fuel tank is off you can clean everything in hot soapy water.  Then you can connect the hoses back up and submerge it under water.  Plug the fuel line and send pressure through the fuel return line and look for bubbles. Buy a new fuel filter, the genuine ones are best.

 

Yes to carb cleaning with carb cleaner.  Buy a carb kit compatible with your make of saw.  I generally find a partial rebuild is fine.  In layman's terms I unscrew each side of the carb in turn and put in new gaskets and diaphragms exactly as they were before.  Whilst the carb is exposed, spray everywhere and with carb cleaner and into the holes and passageways.  Unscrew each jet in turn (H,L,idle) and spray in there too. 

Edited February 20, 2023 by Muddy42

[JohnBoyy]

Taking the fuel tank out is a total saw teardown, the fuel tank is the crankcase on this model saw.

Crankcase for Husqvarna 455 Rancher Chainsaw - OEM No. 510 06 59-14 | L&S Engineers

WWW.LSENGINEERS.CO.UK

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Crankcase for Husqvarna 455 Rancher Chainsaw Genuine Husqvarna Part. OEM No. 510 06 59-14

 

 

So I'll hold off on doing that for as long as possible!

 

don't think it has a spark arrestor but I'll check, if it does it's not much good as she likes to blow sparks when cutting stacks of branches in the sawhorse.

 

I'll get a carb kit, filter and hoses and do some more cleaning.

[Muddy42]

1 hour ago, JohnBoyy said:

Taking the fuel tank out is a total saw teardown, the fuel tank is the crankcase on this model saw.

 

So I'll hold off on doing that for as long as possible!

 

don't think it has a spark arrestor but I'll check, if it does it's not much good as she likes to blow sparks when cutting stacks of branches in the sawhorse.

 

I'll get a carb kit, filter and hoses and do some more cleaning.

 

Ah OK, sorry I have worked on other Huskys where the fuel tank is separate.  Have you tried running the saw without a fuel filter to see if the fuel filter is blocked?  Its not recommended for long periods, but I have done this for testing.  You're going to open up the carb anyway which is where any dirt will end up.  Make sure the fuel tank is really clean - neat unleaded is good for this.