* The fuel sending unit: This is located inside the fuel tank. It's a common failure point.
* The fuel gauge itself: The gauge in the instrument cluster could be faulty.
* Wiring: Broken, corroded, or loose wiring between the sending unit and the gauge is a possibility.
* Grounds: Poor grounding can affect the gauge's accuracy or operation.
Instead of searching for a relay, troubleshooting should focus on those components. A wiring diagram specific to a 1984 Pontiac Fiero will be extremely helpful in tracing the circuit. You can find these diagrams online through various automotive repair resources or in a Haynes or Chilton repair manual for your specific year and model.
