Hi JACUSTOMER-sujds6vx-. Thank you for asking your question on JustAnswer.
If the fuel cap light is on and you can smell fuel then there is a leak in the evaporative emissions system. Generally this needs to be diagnosed with a ford scanner and a smoke machine. Its really not possible to diagnose a vapor leak in the system without this equipment. Being that it is a vapor leak that is why you are not seeing any fuel leaks as there is no liquid in the system. Diagnosis for this concern usually runs about 2 labor hours at whatever your shops labor rate is. You won't know if its a covered item on your extended warranty until you have it diagnosed.