Pentair 250 pool heater

You probably need to change out the pilot generator. That is what tells the gas valve that the pilot is lit. They wear out after a few years.
It's not a tough DIY but you may have to pull the burner tray which involves opening the gas line. A pool tech should be able to change it out for about $130.

first of all dont jumper the gas valve! if the pilot stayson and the burners wont fire there a a few reasons for that. one of your safeties are open.....malfunctioning potentiometer ( tstat control)......or theres a short or voltage drop through the circuit. ur pilot generator should have around 400 dc millivolts. if you follow the path in the circuit and anything drops to the 200dc mark then theres a problem. make sure ur electrical connectors are tight. millivolt models are garbage, as it takes very little to interupt the circuit

If the plot light will not stay lit then usually either the pilot is not sufficiently heating the thermocouple or there is a problem in the pilot control valve. I hope this helps.

check the vent to the outside air for an obstruction

Could be bad coupler or pilot valve is not staying up due to bad spring. If the light does stay lit at all, then the problem is with the fuel.

You can get the entire pilot assembly for $70 at poolcenter.com

clean t burners