Hayward Comfortzone pool heater pilot will stay lit but main burner will not fire. If the TH terminals are jumpered it will, but it won't stay on.

if the pilot stays lit and main burners wont fire you don't need to replace the pilot generator! you have an open safety, poor electrical connection or a problem within the tstat controls

you prolly have an electrical short somewhere. follow the circuit and if any safety is getting around 200-250 dc millivolts then theres the problem. otherwise you have an open safety switch, or tsta controls

check how many millivolts the pilot is generating. if pilot stay lit and burners wont fire u have a problem with one of the safties, lose wire connection, tstat control

I have an H300 Millivolt Hayward heater. It will start and run for about 1 minute then shuts off along with the pilot going out. I've tried cleaning all the terminals and running all new wiring but same result. I've also jumped out the TH to TH terminals leaving the jumper in place and it still shuts down after 1 minute. Any idea what that could be ?

a short circuit in the heater wire will cause an immediate loss of all flame, pilot and main; check the wiring diagram and make sure your pilot wires go to the PP and PP/TH terminals; make sure the terminals are clean and the connection is good; you are dealing with .320 volts DC, any bad connection drops the voltage below the required minimum.

Sounds like the pilot assy needs to be replaced. It has 2 functions one is to light the main burner but also to let the system know that the burner is lit. If it thinks the burners are not lit it turns the gas off

possibly poor pilot adjustment or insuficient mv output from thermopile

Your problem is the pilot generator where the flame is by the burners. This needs to be repalced. That is what is causing the pilot to go out and not start. It is a flame sensor and also tells the gas valve when to release more or less gas.