It sounds as though a fuel leak developed that could be overcome by both pumps running but not with one pump running.

 

The best news is that you are here to tell the tale.

 

I doubt that there was an oil system problem until the last restart.

The rotary can rev up so fast that it is possible to have oil pressure much higher than the relief valve cracking pressure elsewhere in the system. Plus there is a bit of hysteresis in the relief valve (all relief valves). This where the valve will hold one pressure when open and flowing, but requires a bit more pressure to unseat (crack).

 

The rotary oil pressure is controlled by a valve at the end of the system, rather than at the pump as in most engines. So all of the system is at a slightly higher pressure than the cracking pressure all of the time. If you have the stock relief valve in the front cover, it is set at 144 pounds and is there to protect the oil cooler in cold starts. Not a factor here. 

 

The engine being turned by the gear box and the reduction ratio gives the engine a head start on an over rev (A very rapid acceleration)before the RPM is again controlled by the load.

 

Baring a fire as a result of the loss of oil, the engine can run quite a while with no oil pressure at all. Big bearings lightly loaded. My driver has demonstrated that several times.

 

Just speculation on my part.

 

Remember the FAA motto.

 

We're not happy until you're not happy.

 

Lynn E. Hanover