Pressure build up in Husky fuel tank on non runner saw help.

[Arghshh]

Afternoon,

 

I've been playing around with a non-runner saw lately and this Husky 41 has me stumped.

 

Some history;

 

I fitted a new cylinder and piston (circlip had come free from the gudgeon and wrecked them) and new carb diaphragms. Its got good compression at 160psi. The fuel lines are leak free and fuel passes through the fuel line under gravity on its own no bother.

 

I'm going to strip and rebuild the carb again and blast it clean with proper carb cleaner this time rather than just blowing the jets out with air.

 

One thing that I would like advice on is is it normal for a fuel tank on a saw to build up pressure in such a way that it makes the fuel cap difficult to remove, I think a vacuum is being created in the tank which I assume means it's not breathing and so stopping the saw running.

 

Is there a sure fire way of testing the tank breather, which incidentally seems to be a simple non-removable, pressed in the plastic, brass membrane on these saws......

 

Hope this makes sense, and I look forward to ideas and advice.

[slasherscot]

hi

if u take top off carburettor u should have petrol there.......hows the spark have u checked the plug.

 

nothing worse than saw playing up gl

[Arghshh]

Yea spark is fine, I'll check the fuel pump side of the carb for fuel as you suggest when I strip it.

 

Thanks for the reply

[PDGS]

when I got my husky 372xp new it had been run prior to being sent out and when I open the the fuel cap it was very hard to open and a big puff of vapour fumes came out but with fuel in the tank its not a problem it doesnt build up pressure does yours still do it with a full tank

[minnnt]

Sounds like the tank vent may be blocked... if the tank cannot get rid of the pressure through the vent then this will cause it to build up and make the cap hard to undo...

[Arghshh]

Yea it builds up a strong vacuum with fuel in the tank.

 

Can anyone suggest away of pressure testing the fuel tank without buying expensive test kit, I assume emptying the tank and sucking on the filler hole will tell me if the tank vent is blocked?

[ukminch]

Have you tried starting it with the fuel cap off/loose??

[combined tree services]

im pretty sure that some of the older husky's were fitted with venting fuel caps , this was only done for a while as they were not too good . as already stated start the saw leve it run untill it starts to die and then open the fue tank , if it picks up then you have a problem with the breather . hope this is of use to you

[Arghshh]

Have you tried starting it with the fuel cap off/loose??

 

Just tried that, still won't fire.

 

I'm going to strip and clean the carb again and double check everything in there.

[ukminch]

Yer probably best, alternatively I've got one you can have for £50 quid..........