vapor lock problems

[Lifer]

Sid is right on target with the hint about the gas cap! If air can't get into the tank, it's quite possible to build up enough vacuum in the tank that the fuel pump can't overcome it. When this happens, the engine will die and you won't be able to start it until you remove the gas cap. I learned this the hard way with a relatively new (only 8 years old) Cadillac with the new plastic screw-in gas cap. I'd fill up and "run out of fuel" at the 1/2 tank mark on the guage. I dropped the tank and looked to see if the pickup tube had rusted off or developed a rust hole in that area, but it was just fine. Then, a couple weeks later, I noticed that when I went to fill up, I could hear a "whooshing" sound as air rushed into the tank when I unscrewed the gas cap. A $3.00 gas cap from NAPA solved the problem.