In a previous post I was dealing with a Cat pump with reduced pressure. As often happens the simple solution was to just swap it out with a stock electric pump. Then the new electric pump would run great for 10-15 min and shut off. After 3-5 min it would come back on.
The more nozzles were open the longer it would run. Since this seemed like a heating problem - I checked the pressure relief valve to see if it was returning water to the tank. Which it was.
More investigation revealed that the Cat pump uses a 50 PSI relief valve, whereas the electric pump uses a 25 PSI valve. So I was getting too much back pressure causing the pump to overheat.
Now with the proper 25 PSI relief valve - everything works great.
Hope this post saves someone some time.