The fuel pump relay is one of the crucial parts that fires the ignition in a car. The fuel pump relay works to provide electricity to the fuel pump to turn it on and supply the required fuel to the engine. The ignition system or the power-controlling component activates the fuel pump relay.
There are a few signs indicating a fuel pump relay has gone foul. These are:
- Engine stops.
- Engine not starting.
- Fuel pump going silent.
- Turbulent acceleration.
- Engine check light flashes on the dashboard.
So, can a bad fuel pump relay cause misfire?
Well, the fuel pump relay provides power to the fuel pump, any problem with it can cause a hindrance to the flow of fuel to the engine. In short, a bad fuel pump relay will create issue to the ignition which may cause engine misfires as well.
A bad fuel pump can’t provide substantial pressure to the engine to run poorly and misfire it with wavering acceleration. The best way to fix a bad fuel pump is to get it inspected by a professional service personnel and let him do the job.
Experts recommend replacing a faulty fuel pump relay with a new one as the best way to deal with it.
Our thorough research on this point will help readers understand the issues related to fuel pump relays in a better and simple way. Herewith are the points that we are going to cover in this article.
- Can a bad fuel pump relay cause misfire?
- What are the symptoms of a bad fuel pump relay?
- What happens when a fuel relay goes bad?
- What Can Damage A Fuel Pump Relay?
- How do you test a fuel pump relay? How To Replace it?
- How do you start a car with a bad fuel pump relay?
- Can You Run A Car With A Bad Fuel Pump Relay?
Without further ado, let’s jump on to the sections.
Contents
Can a bad fuel pump relay cause misfire?
Yes, a bad fuel pump relay will have issues with the ignition and result in engine misfires. A faulty fuel pump relay will also cause uneven idling plus stalling of the engine.
The fuel pump gets power from the fuel pump relay. If the fuel pump doesn’t receive any power from the fuel pump relay, it won’t function. Any malfunctioning of the fuel pump relay will cause problems with the fuel pump, leading to several troubles affecting your car’s drivability.
One problem which you can notice is the misfiring of the engine. A bad fuel pump relay cannot provide substantial pressure leading to engine misfiring. Before blaming the misfiring entirely on the faulty fuel pump relay, you can also check for depleted spark plugs and faulty wiring.
What are the symptoms of a bad fuel pump relay?
Herewith are a few symptoms to identify a bad fuel pump relay.
Engine stops
If you notice stalling of the engine unexpectedly, it may be a symptom of a bad fuel pump relay. The faulty fuel pump relay cannot supply power to the fuel pump, indirectly stopping the fuel supply to the engine and leading it to stall.
After a while, you can start the vehicle with a partially faulty fuel pump relay but won’t be able to do in the case of an entirely faulty fuel pump relay.
Engine not starting
A bad fuel pump relay will leave the fuel pump dormant without providing it the power it needs to supply fuel to the engine. You may still notice the cranking engine noise while starting the vehicle, but the engine won’t start as it doesn’t get an ounce of fuel.
Engine not starting may be caused due to several other reasons, so it’s inevitable to get your vehicle inspected by a professional mechanic to identify the real reason.
Fuel pump going silent
If you become all ears while starting your vehicle, you often hear a low noise of whine or hum. This noise comes from the fuel pump whenever the fuel pump relay passes power to it to awaken it.
If you hear no noise, it could be due to a bad fuel pump relay. It happens when a bad fuel pump relay doesn’t provide power to the fuel pump, which won’t work without power and remains silent.
Turbulent acceleration
A bad fuel pump relay will affect the fuel pump to supply uneven fuel supply to the engine. As the engine lacks the appropriate fuel quantity, you may experience rough acceleration while driving the car. This situation will eventually lead to stalling the engine to stop the vehicle. Later, it may happen that the car won’t start at all.
Engine check light flashes on the dashboard
An engine check light flashing on the dashboard and you encountering driving problems during the same time frame is a good indicator of a fuel pump relay gone bad. A timely inspection of the fuel pump relay can save you from huge frustration and save your valuable time.
What happens when a fuel relay goes bad?
A failed relay can lead to several problems with your vehicle’s operation. It is that crucial component providing power to fire up the fuel pump enabling smooth flow of the fuel to the engine.
The vehicle needs a regulated flow of fuel to run efficiently. A bad fuel pump may not power up the fuel pump, cutting off the fuel supply to the vehicle and leading to the stoppage of the car unexpectedly.
A faulty fuel pump relay may cause unregulated fuel flow, causing the engine to misfire, rough acceleration, etc. It also drains the battery in the case of a short electrical failure, as the ignition and fuel pump will draw current from the battery once the ignition is “ON.”
The car won’t start due to insufficient fuel supply, but the battery keeps draining.
In some cases, the fuel pump relay may overheat and burn to melt onto the fuse panel. This situation may put a hole in your wallet, as the melted component is hard to remove from the fuse box, and you may have to replace the entire fuse box.
Therefore, a timely check of the fuel pump relay is essential.
What Can Damage A Fuel Pump Relay?
A fuel pump relay may go bad due to several reasons. Commonly, a surge in the electrical power leading to a voltage increase may damage the fuel pump relay. The fuel pump relay has a winding to enable contacts to pass voltage or current.
The contacts may burn in an instance of high voltage or current. In some cases, a shorted signal coil is also the result of a high voltage or current.
How do you test a fuel pump relay? How To Replace it?
Herewith a few steps to test a fuel pump relay and replace it.
Steps:
- Shut the engine off.
- Locate where the fuel pump relay is in the fuse box. (you can Google to find the location of the fuel pump relay of your vehicle or your vehicle’s instruction manual)
- Remove the fuel pump relay by grabbing it firmly and pulling it out from the fuse box terminals.
- Scrap the spikes of the relay with a wire brush. If the relay has been rusted or corroded, try to scrap it as much as you can. You can even use a contact cleaner for electrical parts to clean the corrosion.
- Inspect the circuit on the relay to understand where to connect the multimeter and the power. You will see any 2 points having a connection icon to understand which points are controlling the power. You only need to test these 2 points. Check the numbers that correspond to these points.
- Set the ohm setting on your multimeter. Choose the smallest range on your multimeter to achieve reading accuracy.
- Connect jumper wires to your car’s battery terminal. One wire to the positive and another to the negative.
- Now connect the same jumper wires to the relay terminals- positive to positive and negative to negative.
- You may hear a “click” sound once you connect the power. If you hear it, the relay is working. If not, then there is a problem with the relay.
- Replace the faulty relay with a new one by re-attaching the fuse box.
How do you start a car with a bad fuel pump relay?
You will be able to start your car with a bad fuel pump relay by applying a few methods:
- External pressure: You can apply manual pressure externally to start your car. You can achieve this by connecting an air pump to the fuel tank and operating it to pressurize the fuel tank.
- Maintaining engine temperature consistently: A bad fuel pump relay may overheat the engine. Take a break from driving the car to cool down the engine. It will help to reset the fuel pump without any pressure.
- Connect fuel pressure meter: You can fit this meter into your vehicle’s engine. It will enable you to check whether the pump is working correctly or not and help you to restart the car.
Can You Run A Car With A Bad Fuel Pump Relay?
In the case of a partially bad fuel pump relay, you will be able to drive your car with hiccups and sometimes unexpected stalling of the vehicle. Because the fuel pump may provide an uneven fuel supply to the engine, causing rough acceleration in some cases.
A fuel pump relay may also not work ideally due to a wiring or electrical shorting issue. If you notice these problems, you should get your gas inspected the earliest by a professional mechanic.
Frequently Asked Questions (FAQs)
How Much Does It Cost To Have A Fuel Pump Relay Replaced?
Commonly the new fuel pump relay will cost approximately $25. Plus the labor charges of a mechanic will depend on the locality.
How often Should You Replace Your Fuel Pump Relay?
Averagely, a fuel pump relay will run for 1,60,000 to 3,00,000 km when you drive your car daily for 8 to 15 years.
What Are The Causes Of Engine Misfiring? Explain What Can Also be the Cause of a Misfire?
A bad fuel pump relay can cause an engine to misfire. Apart from this, herewith is a list of other issues that may cause engine misfires.
☑️ Absence of or Worn-out spark plugs.
☑️ Clogged fuel injectors.
☑️ Imbalance in the air-to-fuel ratio.
☑️ Worn-out piston rings.
☑️ Blown gasket.
☑️ Transmission problems.
☑️ Prattling clutch.
☑️ Clinging brake pads.
Conclusion:
A fuel pump relay is a tiny component resting in the fuse box. But it’s one of the crucial elements that provides power to the fuel pump, enabling it to supply fuel to the engine.
A bad fuel pump relay may cut the power of the fuel pump, resulting in engine misfire, engine stalls, car stopping midway, etc. A fuel pump relay issue should be resolved at the earliest; to prevent further damage to other parts of your car.
