P3193 on 2013 Prius

Hi All,
I'm new here and hope you all can help me out. About 6 weeks ago, I was driving my 2013 Prius (120k miles) on a dry sunny day on a flat stretch of road. 1/4 tank of fuel reading on the dash. Inexplicably, my wife and I both heard a single "thunk" noise come from the back seat area of the car. We had not run over anything, but it had that kind of sound. We both mentioned that it sounded out of the ordinary, but the car kept driving until we got to the restaurant about three miles away (mostly downhill). We parked, walked into the restaurant, decided the wait was too long and went back to the car. When I started the car, it backed out the parking spot and died (I don't think the ICE had come on at all). I got a "Check Hybrid System Stop Vehicle In A Safe Place" warning with other warning lights. I had the car towed home. With an OBD2 reader, I got P3190 "Poor Engine Performance" and P0A0F "Hybrid Drive System - Engine Failed to Start". After clearing these codes, I was able to get the ICE to start, but it would only run for 20 seconds or so before dying. I could hear the fuel pump come on, but the car wouldn't stay running. I also checked with a meter and measured 12v at the pump connector. Because the "thunk" noise sounded it like it came from under the back seat, I was laser focused on a mechanical failure of the fuel pump. Not wanting to go all in with a $400 - $600 new OEM fuel pump, I bought a used one for $100. I did a visual check under the hook and removed the MAF to make sure some junk was clogging it up. Anyway, like I said the thunk noise from the back of the car had me convinced it was not an under-the-hood problem. Yesterday, I finally got around to installing the used fuel pump. I also added about 5 gallons of gas for good measure. This got me basically nowhere. I can hear the fuel pump run at a low hum after I hit the start button. The car will run for 20-40 seconds and die. Also, now the fuel gauge reads dead zero with the last pip blinking. Therefore, I get code 3193 "fuel run out". Seems like my hunch of the fuel pump being bad was incorrect. What else could it be? What was the thunk sound I heard from the back of the car? My wife and I are 100% sure we didn't run anything over to cause the sound. For some reason, the ICE is not getting the correct fuel air mix. Tomorrow, I plan to spray the MAF with cleaner, but I doubt that makes a huge difference.
Gracias

 

One thing I forgot to mention above. When I start the car, my OBD2 sensor shows Fuel System Status "Unknown"

 

@Mendel Leisk Thanks for the reply. Good point about the ICE not actually running. As far as filling up, I always remove the pump after it clicks off the first time. Provided it has delivered approximately what I expected. I called a local dealership yesterday. They charge $204 for diagnosing a problem. That seems cheaper than throwing parts at it. I'll have it towed there (AAA) and see what they determine. Depending on what they find, I might tow it back home and repair or just let them do it.