I was at an unfamiliar pump on a road trip once. I could NOT get the pump to turn on. I went to the office and got the attendant to come out and get it going. He pointed out immediately that I had the gasoline nozzle in my tank and was trying to push the diesel button....Their gasoline nozzle had a green cover on it....
I did same thing, gas nozzle had green and diesel had Yellow, think it was around Pa., caught it after putting a gallon in, then topped it with 35 gallons diesel, no problems with it