No starter operation?

My truck HD2500, crew cab will not start sometimes. I can drive somewhere come back out and it won't turn over. Makes a sound like the fuel pump or something is engaging. The PRNDL will light up and the battery light will light up. Nothing else happens. No other lights on the dash. No gauge movement. Interior lights and radio work. Once it gets towed to the shop. It fires right up. Might work for two weeks and then randomly won't start. The last time I was in a drive through and I opened the car door and it shut off. Tried to start it and same behavior. Once it got to the shop no problem.