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Petrol-powered Brushcutter support
The purge bulb on my grass trimmer or brushcutter does not seem to work. What is wrong?
If the purge bulb on your Husqvarna grass trimmer or brushcutter does not seem to work, it is usually caused by a fuel system issue such as incorrectly connected fuel lines, a blockage, a damaged fuel line or a lack of fuel in the tank.
This guide explains how the purge bulb works, the most common symptoms and want to check before contacting a service centre.
What does a purge bulb do?
The purge bulb helps move fuel through the fuel system before starting the engine.
When pressed, it:
Draws fuel through the fuel filter, fuel line and carburettor.
Pushes excess fuel back to the fuel tank through the return line.
This process helps the engine start more easily, especially when cold.
Quick troubleshooting guide
| Symptom | Possible cause | What to check |
| Purge bulb will not compress | Fuel lines connected incorrectly | Check fuel line routing |
| Purge bulb stays compressed and does not return | Blocked fuel filter, fuel lines or carburettor | Inspect for restrictions |
| Purge bulb works normally but no fuel moves | Empty fuel tank or damaged fuel line | Check fuel level and fuel lines |
| Purge bulb feels soft or damaged | Cracked or worn bulb | Inspect bulb condition |
The purge bulb will not compress
If the purge bulb cannot be pressed, the fuel lines may be connected incorrectly.
What to do:
Inspect the fuel lines.
Verify that the fuel supply and return lines are connected to the correct locations.
Refer to your operator’s manual if you are unsure of the routing.
The purge bulb stays pressed in
If the purge bulb does not return to its original shape after being pressed, there may be a restriction somewhere in the fuel system.
Check the following:
fuel filter
fuel lines
carburettor
A blockage can prevent fuel and air from moving correctly through the system.
The purge bulb works but does not move fuel
If the purge bulb appears to operate normally but no fuel is visible moving through the system:
Check the fuel tank
Make sure there is enough fuel in the tank. This is one of the most common causes.
Inspect the fuel lines
Look for:
cracks
splits
loose connections
holes
Even a small air leak can prevent the purge bulb from drawing fuel correctly.
Inspect the purge bulb for damage
Over time, the purge bulb can become:
cracked
brittle
worn
leaky
If the bulb is damaged, it may not create the vacuum needed to move fuel through the system.
Replace the purge bulb if you notice any visible damage.