40 Fuel Pump Relay Wiring Diagram

Fuel Pump Rewire Relay Diagram for DUAL in tank pumps DSMtuners
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Welcome to our blog post on fuel pump relay wiring diagrams. In this article, we will be discussing the importance of fuel pump relays, how they work, and providing you with a detailed wiring diagram to help you understand the electrical connections involved. Whether you are a car enthusiast, a DIY mechanic, or simply curious about automotive electrical systems, this article aims to provide you with valuable information and insights. So, let's dive in!

What is a Fuel Pump Relay?

A fuel pump relay is an essential component of a vehicle's electrical system. It is responsible for controlling the flow of electrical current to the fuel pump, ensuring that the pump only operates when necessary. This is crucial for fuel efficiency, as it prevents the pump from running continuously, thus reducing unnecessary power consumption.

Function of a Fuel Pump Relay

The primary function of a fuel pump relay is to control the activation and deactivation of the fuel pump. When the ignition switch is turned on, the relay receives a signal from the engine control unit (ECU) or the ignition module. It then energizes the fuel pump, allowing it to deliver fuel to the engine. When the engine is turned off, the relay cuts off power to the pump, preventing it from running unnecessarily.

Importance of a Fuel Pump Relay

A fuel pump relay plays a crucial role in the overall performance and efficiency of a vehicle's fuel system. Without a properly functioning relay, the fuel pump may continue to operate even when the engine is off, leading to unnecessary fuel consumption and potential damage to the pump itself. Additionally, a faulty relay can cause intermittent or complete loss of fuel delivery, resulting in engine stalling or failure to start.

Fuel Pump Relay Wiring Diagram

To help you understand the wiring connections involved in a fuel pump relay, we have provided a detailed diagram below:

Fuel Pump Relay Wiring Diagram

Understanding the Diagram

The fuel pump relay wiring diagram consists of various components and connections, each serving a specific purpose. Let's break down the diagram and explain each element:

1. Power Source

The diagram starts with the power source, which is typically the battery. The positive terminal of the battery is connected to a fuse, which acts as a safety mechanism to protect the electrical system from overloads and short circuits. From the fuse, a wire leads to the fuel pump relay.

2. Fuel Pump Relay

The fuel pump relay is depicted as a rectangular box with four or five terminals. Each terminal represents a specific connection point. The relay receives signals from the ECU or ignition module and controls the flow of current to the fuel pump. It also receives power from the fuse and distributes it accordingly.

3. Fuel Pump

The fuel pump is represented by a symbol resembling a small electric motor. It is connected to the fuel tank and delivers fuel to the engine. The fuel pump receives power from the fuel pump relay, allowing it to operate when the engine is running.

4. Ground Connection

A ground connection is essential for the proper functioning of the fuel pump relay and the overall electrical system. In the diagram, the ground connection is depicted as a line with multiple branches, indicating various points where the ground is connected to the vehicle's chassis.

5. Engine Control Unit (ECU)

The ECU is the brain of the vehicle's electrical system. It sends signals to various components, including the fuel pump relay, to control their operation. In the diagram, the ECU is represented by a box with multiple input and output connections.

Wiring Connections

Now that we have explained the components in the diagram, let's delve into the wiring connections involved:

1. Battery Positive Terminal

The positive terminal of the battery is connected to a fuse through a wire. This provides the initial power source for the fuel pump relay and other electrical components.

2. Fuse

The fuse acts as a safety device, protecting the electrical system from overloads and short circuits. It is connected to the fuel pump relay, ensuring that power is distributed safely.

3. Fuel Pump Relay Terminals

The fuel pump relay has multiple terminals, each serving a specific purpose. These terminals include power input, power output to the fuel pump, ground connection, and signal inputs from the ECU or ignition module.

4. Fuel Pump Terminal

The fuel pump terminal is where the fuel pump is connected to the relay. When power is supplied to this terminal, the fuel pump starts operating, delivering fuel to the engine.

5. Ground Connections

The ground connections are crucial for completing the electrical circuit. These connections ensure that the fuel pump relay, ECU, and other components have a reliable path for current flow.

6. ECU Signal Inputs

The ECU sends signals to the fuel pump relay, instructing it when to activate or deactivate the fuel pump. These signals are crucial for efficient fuel delivery and overall engine performance.


In conclusion, understanding the fuel pump relay wiring diagram is essential for anyone working with automotive electrical systems. By grasping the connections and components involved, you can diagnose and troubleshoot issues related to the fuel pump and relay. Remember, always consult the vehicle's specific wiring diagram and follow safety precautions when working with electrical systems. We hope this article has provided you with valuable insights and knowledge. Happy wrenching!

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