Husqvarna 460 Rancher fuel breather problem

[adw]

I still find it hard to believe it’s the tank breather, they are so reliable, and if it’s a new genuine breather there will not be an issue with it, have you checked the impulse hose? it runs from the side of the cylinder to the housing where the carb sits on.

If all fails I can send you a shop manual for it to help you.

[JohnBoyy]

Yeah there's definitely something bigger wrong, the breather is only highlighting the problem.

 

It's also definitely getting worse on restarts.

 

Have a pair of forceps on the way in the post, I don't fancy taking the carb off and not being able to get the fuel supply hose back on, it's a bit of an awkward spot under the carb.  once that lands I'll dive into cleaning the carb and see how it goes.

[Muddy42]

1 hour ago, JohnBoyy said:

Yeah there's definitely something bigger wrong, the breather is only highlighting the problem.

 

It's also definitely getting worse on restarts.

 

Have a pair of forceps on the way in the post, I don't fancy taking the carb off and not being able to get the fuel supply hose back on, it's a bit of an awkward spot under the carb.  once that lands I'll dive into cleaning the carb and see how it goes.

 

Totally agree.  As I said in post 3, I think there is something else wrong with the fuel delivery system, that can be masked by opening up the fuel cap or breather valve.  Buy the right carb kit, spray carb cleaner and disassemble and replace each side of the carb's diaphragms.  I find it safer to clean and tackle each side in turn. Be liberal with the carb cleaner, spray it in everywhere - you can even get tiny bottlebrushes - H/L screws, needle/ regulator arm/ tiny fuel guaze. Check meter height.  Pressure test and replace fuel lines and purge lines. Lots of youtube videos on this.

[adw]

Just a thought, the carb metering side cover plate has a small hole in it, this allows atmosphric pressuer to depress the metering diaphram, if this is blocked you will have symptoms like this, easy to check without removing the carb.

[Muddy42]

It seems stupid now, but I missed the holes in this fuel line when I first checked a chainsaw.  Photo below.  when I checked again (after rebuilding the carb) I found the signs that this hose was perishing.

 

Its worth really checking these lines, bend the rubber about and really scrutinize it in good light. and pressure test whilst doing so.

 

[spudulike]

Well at least you have learnt a bit about saws and their fuel systems. The simple way of testing a line is to plug or clamp one end and to use the Mityvac on "pressure" and see if it leaks. It will only test for integrity of the line and not the overall condition but it does prove if the line is holed or not.

Sounds like you are getting there.

[JohnBoyy]

Thread revival!

 

I was busy with a million things in the spring so I just worked on with the stihl 180 and a little ego battery saw.  we took down a dozen ash trees in the spring and there was loads of tops to be cleaning up with the small saws.

 

I took the carb off and could see nothing wrong.  these saws have a rubber inlet manifold which seemingly can also crack but it looked perfect so I got a rebuild kit and took the carb apart.  I didnt 100% strip it out of fear of not getting it back together properly, didnt remove the jets/needles.

 

I couldnt see anything glaringly obviously wrong, maybe the pump diaghpram was dodgy, or maybe I damaged it taking it apart.  Eiether way I put it back together with a new fuel fiter and hose and with some fresh juice it fired right up.  I've only done some relatively light work with it yet but it didnt seem to struggle or splutter at any point so I'm hopeful that I've done it right.  

 

I need to watch some more tuning videos on youtube to be sure I have the carb set right, last thing I want is to end up running lean.

 

 

Thanks for all the advice folks.

[adw]

Be careful following some of the YouTube videos, they can be very miss leading.