Cadillac: gas gauge flashes Empty, gas gauge, cadillac deville

Question
I have a 1988 cadillac deville which was given to my wife when her aunt died. 179000 miles, and was parked for 5 yrs in her garage. I had the injectors stuck when i first tried to start it. Now i notice it starts quickly, but the gas gauge shows an E flashing and it only held a couple dollars worth of gas before it spit it out and refused to take anymore. could it be a sensor for the full and not big bucks?

Answer
We need to check the computers for fault CODES:

1. Ignition ON. Engine OFF.

2. Simultaneously push and hold the OFF and WARMER buttons for 3 seconds and release them.

3. Codes will start to appear and the display will stop at .7.0

4. Write down the codes in the EXACT order in which they display and let me know what they are.

5. turn ignition OFF.