A fuel pump relay is an electronic switch that controls the flow of fuel from the tank to the engine. When the relay fails, the engine will not start or may stall while driving. In this blog post, we will discuss the common causes of fuel pump relay control circuit problems and the steps you can take to fix them.
Symptoms of a Failed Fuel Pump Relay
- The engine cranks but does not start
- The engine stalls while driving
- The engine starts but runs poorly
Causes of Fuel Pump Relay Control Circuit Problems
- Failed relay
- Faulty wiring or connections
- Failed PCM or BCM
Steps to Diagnose a Failed Fuel Pump Relay
- Check the fuse and relay
- Test the fuel pump
- Check the wiring and connections
- Check the PCM or BCM
Step 1: Check the Fuse and Relay
The first step in diagnosing a fuel pump relay problem is to check the fuse and relay. The fuse is located in the fuse box, usually under the hood. It is a small, plastic box with a metal strip inside. If the fuse is blown, replace it with a new one. The relay is usually located in the same area as the fuse box and is a small, plastic box with several prongs. If the relay is not functioning properly, it will need to be replaced.
Step 2: Test the Fuel Pump
The next step is to test the fuel pump. The easiest way to do this is to use a fuel pressure gauge. Connect the gauge to the fuel rail and turn the key to the on position. The pressure should be within the manufacturer’s specifications. If the pressure is low, the fuel pump may be failing and will need to be replaced.
Step 3: Check the Wiring and Connections
If the fuse and relay are fine and the fuel pump is working properly, the next step is to check the wiring and connections. Make sure all connections are clean and tight. Check for any frayed wires or broken connections. If any are found, repair or replace them.
Step 4: Check the PCM or BCM
If all the above steps have been completed and the problem still exists, it is likely that the PCM or BCM is the cause of the problem. The PCM (Powertrain Control Module) or BCM (Body Control Module) is responsible for controlling the fuel pump relay. If it is not functioning properly, it will need to be replaced.
- Always make sure the car is in park and the emergency brake is on before working on the car.
- Always wear safety glasses when working on a car.
- Always disconnect the battery before working on the electrical system
- Always refer to the vehicle service manual for specific instructions on the make and model of the car.
In conclusion, a fuel pump relay control circuit problem can be caused by a failed relay, faulty wiring or connections, or a failed PCM or BCM. By following the steps outlined in this blog post, you can diagnose and fix the problem. Remember to always refer to the vehicle service manual for specific instructions and precautions.