Depending on the model year of your Hyundai, the gas tank door may be opened mechanically or electronically. Each will have its own method of troubleshooting. In either case, if the signal to open the gas tank door is not reaching the release lever on the gas tank, the door will not open. The issue resides in one of three components: the switch, the connection or the release level. Each must be inspected in order to determine the source of the problem.
Inspect the switch that opens the gas tank door. The switch should be on the left side of the driver's seat. Inspect the switch. Older models (mid-90s and earlier) will have a mechanical switch; newer models will have a switch that sends ae electronic signal to the gas tank door. A mechanical switch, when pulled, should pull a cable forward. Check to make sure this cable has not been severed.
Open the gas tank door. Inspect the release lever. Have a friend pull the release switch in the car while you watch the lever. What happened when the switch is pulled? Does the release lever move, or does it remain still? In mechanical release switches, the cable connected to the release lever should be pulled to release the gas tank cover. Check to make sure the cable is still intact and attached to the lever. If it is, then check the lever itself as the issue may be in the lever.
Replace the switch and the lever in electronic models. Unfortunately, the only way to know which part of the unit is the issue is to replace either the switch or the release lever. Replacement parts can be purchased from Hyundai or an authorized retailer.
