Husqvarna Mower Dies When Blades Engaged
So what's up when a Husqvarna mower dies, when the mower blades are engaged? The mower grass box is not fully closed, which causes the safety sensor to remain open. Other possible causes include:
- Grass Box Misaligned
- Grass Box Sensor Wiring Loose
- Grass Box Sensor Faulty
- Bad Gas
- Carburetor Dirty
- Carburetor Faulty
That's a list of all the most likely reasons that the engine dies as you apply the blade button or lever.
Now lets take a look at how we can quickly figure out what's going on and how to fix it.
Grass Box May Not Be Fully Closed
Grass Bag Misaligned
If your grass box won't close properly, removing the wiring from the back of the sensor and connecting them together will by pass the sensor.
You can use a piece of wire but a car fuse works the best.
Loose Grass Bag Sensor
Grass Bag Sensor Faulty
Grass Bag Sensor
The Husqvarna grass bag sensor is a four pin, although some mowers will only use two of them.
The sensor is fitted to other components that utilize the four pins.
Testing The Sensor
Set the volt meter to ohms, and check for continuity when the sensor is pressed.
The meter should read close to zero ohms, if not replace it.
Bad Gas Causes Poor Running
A lawnmower engine is very simple and forgiving. The carburetor that's bolted to it, is neither of those things. It's a finely tuned piece of kit, any slight change in the air/fuel balance will cause the mower engine to run poorly.
A carburetor has two jobs, mix the gas to air at a ratio of 14.7:1 and to supply the correct amount of this mixed gas to the engine for any given engine load demand.
Dirt in any of these components, will cause fuel starvation, which in turn causes the mower to not start, lack power or stall when the engine is loaded.
Common causes of fuel starvation are:
- Gas tank outlet blocked
- Gas filter blocked
- Gas valve faulty
- Gas lines blocked
- Needle valve dirty
- Fuel bowl dirt
- Fuel jet blocked
- Failed fuel pump
Check out my complete carburetor troubleshooting guide (internal link).
John Deere mower dies when blades are engaged? Your grass box is not fully closed, the safety sensor is shutting down the engine.
What causes a 4 stroke engine to backfire? A bad plug is a common cause of backfiring, but other possible causes include:
- Wrong plug type
- Faulty carburetor
- Broken shear-key
- Faulty shut down valve
- Stale gas / wrong type gas
- Intake vacuum leak
- Cylinder carbon build-up