How to Check a Fuel Pump Relay in a Hyundai Excel

Power supply to the fuel pump on your Hyundai Excel is handled by the control relay or switch. This relay also supplies power to the injectors and the electronic control unit (ECU) or computer. Like any other electro-mechanical relays, this control switch contains movable points and coils that may burn or break. To confirm that the fuel pump relay on your Hyundai model is the cause of the problem, test it and replace it if necessary.

Things You'll Need

  • Ohmmeter 2 jumper wires
  • Identify the control/pump relay terminals. If you set the relay with the terminals facing you and the lock tab pointing up, these would be the terminal identification numbers. Top row, from left to right: 4, 3, 2 and 1. Lower row, from left to right: 8, 7, 6 and 5.

  • Set your ohmmeter to read within the 100 ohms range.

  • Hook up the ohmmeter leads to relay terminals 1 and 4. You should get an infinity reading or no conductivity.

  • Hook up the ohmmeter leads to relay terminals 2 and 8. Your meter should indicate a reading value close to 95 ohms.

  • Hook up the ohmmeter leads to relay terminals 3 and 8. Your meter should indicate a reading value close to 95 ohms.

  • Hook up the ohmmeter leads to relay terminals 6 and 7. Your meter should indicate a reading value close to 35 ohms.

  • Hook up the ohmmeter leads to relay terminals 1 and 2. Now your meter should indicate an infinity reading or no conductivity.

  • Hook up the ohmmeter leads to relay terminals 1 and 4. Jump terminal number 6 to the negative terminal on your car battery using a jumper wire and momentarily apply battery voltage to terminal number 7 using another jumper wire. Your ohmmeter should indicate a reading of 0 ohms.

  • Hook up the ohmmeter leads to relay terminals 1 and 2. Jump terminal number 5 to the negative terminal on your car battery using a jumper wire and momentarily apply battery voltage to terminal number 7 using another jumper wire. Your ohmmeter should indicate a reading of 0 ohms.

  • Compare your results with the reading values given in steps 3 through 9 above. If your results differ from these values, replace the control relay.