Typically this is due to one of two reasons. Either a QCC flow restriction has happened, which can be cleared, or there is a faulty part which we will replace. Below are the steps to clear a QCC flow restriction. 

1. Close the tank valve.
2. Disconnect the assembly from tank. 
3. Open the brass control valve. 
4. Close the brass control valve. 
5. Reattach the assembly to tank. 
6. Open tank valve. 
7. Set regulator to around 20 psi.
8. Crack open brass control valve and light burners. 

If the pressure still drops contact Farmer's Friend for a replacement part.

It is worth noting that the order in which you light the Pyroweeder can cause it to trip. The lighting instructions are in the manual, but basically you must work your way from the tank valve up to the brass control valve. Starting psi should be around 20 psi or less.   

See attachment below for pictures with steps.