1998 528i vapor lock

When trying to start my '98 528i, the starter engages, but is not able to turn over the car. I've checked the battery and the starter and both are fine. I brought it to the dealer and they told me that the fuel injectors are staying open when the car is off and dumping fuel into the cylinders which is creating vapor lock in the cylinders. The dealership to this point is not able to tell me what the root of the problem is. Has anyone ever experienced this or does anyone have any suggestions as to why the injectors would stay open? Thanks.