Stihl blower carb primer question

[ipbr21054]

Primer bulb is empty thus blower not starting. There are no splits in the bulb & fuels lines are intact & not split etc.
I sprayed carb cleaner directly into the air filter & after a few pulls got it started.
I was able to pump the primer & could now see fuel in it.
Switched it off & am I correct in thinking the fuel that’s there should stay there as it seemed to be empty.

I pumped a few times & got it started & it happily ran no problem for at least 5 minutes.

So should primer keep fuel inside or does it drain out ?

Looking for reasons if it’s empty but should keep fuel inside otherwise.

 

[Burnerman]

After storing the machine for a while the primer bulb may empty with fuel draining back to the tank.
Pressing the primer fills the carb with fuel to aid starting, excess returns back to the tank, you will be able to see.
Once started, the primer remains full, but it’s really just there to aid a cold start.
There is a rubber flap valve below the primer bulb to retain the fuel, which seems to be passing in this case.
John

 

[ipbr21054]

Sometimes when pressing the primer bulb i dont see any fuel, i mean i could press it 3/4 times & nothing.
After a while i do see fuel but it seems to be a different situation from my other petrol tools that i use.

So do you think its the rubber flap under the primer bulb at fault.

 

[Burnerman]

If you think about it, there has to be one way valve somewhere as otherwise you would be just blowing air into the fuel tank and not getting very far.
If I recall, there is a white plastic block below the primer bulb and the valve is in there (I think!)
John

 

[ipbr21054]

Ah ok cheers.
Sometimes when operating i do hear say AIR being blown back into the tank.
I expected to here a gurling noise BUT i dont, i hear air when bulb is empty.

This would then explain why the primer takes 3/4 tries & becoming empty