One problem related to other fuel system tank mounting has been reported for the 1999 Jeep Grand Cherokee. The most recently reported issues are listed below.
The fuel tank skid frame supporting the fuel tank has rusted through. This part is designed to hold the fuel tank with no other means of support. Once this fails the fuel tank dislodges and has the potential to separate from the vehicle. This vehicle is being investigated by NHTSA and Chrysler has recently stated that the skid frame provides protection for the plastic fuel tank mounted behind the rear axle. It fails prematurely due to its inadequate thickness and water/salt catching design. There is no way to prevent the corrosion and perform maintenance without removing the skid frame/fuel tank . A recall to install a thicker gage metal corrosion resistent skid frames is needed. Many 1999-2004 Grand Cherokee Jeeps are vulnerable as their skid frame supporting fuel tank decay. Many reports of people who have the wj Jeeps are having this problem per the internet/Jeep forums.