I once had a piece of glue come loose from the baffle inside the fuel tank. It blocked the fuel line. After it caused the flameout, I realized it was not acting right when I took off.
Also, on another jet, the vent got partially plugged and the engine would not spool up to full RPM. But if staying on asphalt, I would figure that a blocked vent is probably not the problem as it was running O.K. initially. A P-60 vent is usually small I.D. If you are not on asphalt, I would check the vent.
However, the failure to start is also classic for a low/bad battery condition. I would try a different fully charged battery. What battery type are you using? You can charge NiMH's and get false peaks. But I am assuming you are using LiFe or LiPo for the ECU cause NiMH typically just can't consistently deliver the current needed for a good start.
Not sure what the PV range is on a P-60. A PV 1.1 at 90K R seems low. If a different fully charged battery gives the same result and fuel system is not blocked, then pump is probably failing. But, if the filter is located in the right place (i.e. after the pump) and pump is going bad you probably also should be seeing debris in the filter. For me, it is a good idea to carry a spare pump for turbines that have external pumps. They come in handy for testing as well as preclude a lot of delay time while waiting for UPS and back orders, etc.
Just some thoughts to eliminate a few assumptions.