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Common Failures Of A Bad Fuel Pump Relay!

Your car contains a wide range of relays, including one for the fuel pump. Like any other relay, the fuel pump relay can eventually fail. When this happens, the fuel pump will no longer work as it should and your car will start to show some noticeable symptoms. To prevent your relay from going bad, read about common faults for a bad fuel pump relay .

What does a fuel pump relay do?

A relay is basically an electromagnetic switch that uses a low current to control a higher current circuit. Inside the relay, you’ll find a coil and a switching mechanism with a set of contacts. Most automotive relays are normally open, which means that current does not flow between the contacts until the relay is activated.

In a typical automotive fuel pump circuit, a control module activates the relay. When the module deems that the conditions are correct, it supplies ground to the coil inside the relay, causing current to flow through the coil . The current flowing through the coil creates a magnetic field that causes the relay contacts to close. Current then travels through the contacts to the electric fuel pump, causing it to turn on.

Once activated, the electric fuel pump moves fuel from the tank to the fuel injectors on the engine. The injectors supply the fuel necessary for the engine to run.

Common signs and faults of a bad fuel pump relay

When the fuel pump relay goes bad, the fuel pump does not work properly. As a result, you’ll notice one or more of the following common failures from a bad fuel pump relay.

Note: Because other problems can present the same symptoms as a faulty fuel pump relay, you’ll want to perform a thorough diagnostic on the vehicle before replacing any part.

1. Engine cranks but won’t start

The most common sign of a bad fuel pump relay is an engine that starts but won’t. A fuel pump relay will often fail in the open position, preventing voltage from reaching the fuel pump. As a result, the engine runs out of fuel and refuses to start.

2. The fuel pump runs continuously

Although rare, there are cases where the fuel pump relay can stick closed, causing the fuel pump to run continuously. The problem can occur in circuits that supply power to the fuel pump fuse at all times. In this case, you will hear the fuel pump running continuously, even when the key is out of the ignition.

3. Illuminated check engine light

In some vehicles, the engine computer, often referred to as the powertrain control module (PCM), monitors the fuel pump relay and its circuit. If the PCM detects a problem, it turns on the check engine light and stores a corresponding Diagnostic Trouble Code (DTC) in its memory .

The P0230 “Fuel Pump Primary Circuit” code is one of these codes. Please note, however, that this code is not compatible with all makes and models. Therefore, not all vehicles will turn on the check engine light for a faulty fuel pump relay.

Frequently asked questions and answers

Once you know a little about what are the problems that an important part of your car can present, you will have some doubts in mind. We bring you here the most asked questions with their answers.

1. How can I test a fuel pump relay?

Automotive relays are usually very similar. The easiest way to test a fuel pump relay is to temporarily swap it out with another (unimportant) relay from the power distribution box.

For example, you can interchange the fuel pump relay with the air conditioning compressor relay if the two relays share the same design . If the fuel pump works with the alternate relay installed, you know the fuel pump relay needs to be replaced.

You can also test almost any automotive relay, including a fuel pump relay.

2. Where is the fuel pump relay located?

The fuel pump relay is normally located in the power distribution box in the engine compartment. Consult your owner’s manual if you need help finding the relay.

3. Will a bad fuel pump relay throw a code?

As mentioned, a bad fuel pump relay can cause a code in the PCM, but only on certain cars.

4. How much does it cost to replace the fuel pump relay?

Replacing the fuel pump relay is a do-it-yourself repair. A fuel pump relay is usually less than $20 for the part alone. Of course, the exact cost will vary depending on a variety of factors, such as the year, make, and model of your vehicle.

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