An OBD2 code reader will point to the likely cause if the MIL remains.
Peter, I have one of these
https://www.ebay.ch/itm/376399817150. Inexpensive and easy to use (but check that it matches the shape/size of your OBD port). I'll bet you will see code P0627 which is a very common fault in the fuel sender. Just delete the code and that will turn-off the MIL light.