How To Diagnose A Failing Fuel Pump: Common Fuel Pump Problems
The fuel pump transports gasoline from the fuel tank to the engine. If it fails, your car won’t start. Fortunately, there are several warning signs before a complete breakdown occurs. If you think your fuel pump might be failing, it's important to attend to it immediately. This guide will help you identify and fix common issues with your fuel pump.
Symptoms Of A Failing Fuel Pump
If the fuel pump is malfunctioning, your engine may get an inconsistent fuel supply. Or the fuel pressure might be too low. These issues can lead to poor engine performance. Should you notice any of the symptoms listed below, it might be time to consider replacing your fuel pump:
- Difficult starting: If your engine requires many attempts to start, the pump might not be delivering adequate fuel.
- Loss of power when accelerating: A failing fuel pump may work under light loads, but fail to supply enough fuel during hard acceleration.
- Random stalling: Is your vehicle stalling at stop lights or hesitating during acceleration? It could be due to intermittent drops in fuel pressure. Or a clogged fuel filter.
- Noises from the gas tank: Since the fuel pump is in the fuel tank, unusual whirring or whining sounds from this area may mean the pump is failing.
- Limp Mode: In some cases, the car detects an insufficient fuel supply and goes into limp mode.
Fuel Pump Troubleshooting
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If you're not sure whether the fuel pump it the cause of the issues you're having, you'll want to trouble shoot the problem a bit. To do this, you'll need:
- Fuel pressure test gauge
- Fuel Filter (if clogged)
- Voltmeter
- Screwdrivers and ratchet set
- Service manual (to check fuel pump flow and voltage figures)
There are a few things you can do to narrow down the problem:
1. Replace The Fuel Filter
Contaminated fuel may result in a clogged fuel filter, which can produce symptoms similar to those described above. It's important to replace the fuel filter according to the manufacturer’s recommended schedule. Additionally, it's wise to change the fuel filter whenever you replace the fuel pump.
Failing to replace a dirty filter can allow contaminated fuel to reach the new pump, potentially damaging it. If the filter is blocked, you will continue to face the same performance issues. (Be aware that not all Mazda's have an external fuel filter. Some are located in the fuel tank at the pump inlet.)
2. Test The Fuel Pump Pressure
If the car starts but isn’t running smoothly, it might be due to low fuel pressure. You can attach a fuel pressure gauge to your vehicle's fuel system. There is usually a dedicated pressure test port.
Ask someone to rev the engine while you monitor the gauge. Then, compare the pressure readings with the service manual specs to determine if the pump is faulty.
3. Test The Fuel Pump Voltage
If your car fails to start, it's possible that the fuel pump has completely failed. To troubleshoot, you should:
- Examine the electrical wiring for any signs of corrosion.
- Inspect the relay for any burn marks on its connectors.
- Check the relevant fuse in the fuse box to see if it has blown.
If these components appear to be in good condition, then use a voltmeter to measure the voltage at the fuel pump’s terminals. Compare this reading to the voltage of the car’s main battery. If the voltage at the pump is significantly lower, this could mean that the pump’s connectors are worn. This will increase resistance levels.
4. Check The Relay And wiring
Fuel pump relays can fail or work intermittently. Test the relay with a voltmeter, or ask your mechanic to do it for you. If they have a replacement relay, swap it out to see if it solves the problem. Corroded wiring to and from the fuel pump, can also cause intermittent issues.
OEM Replacement Fuel Pumps From REAL Mazda Parts
If your diagnosis reveals the fuel pump to be faulty, you should only use OEM replacement components. They are designed to fit perfectly and function exactly like the original. Choosing aftermarket parts could potentially damage your fuel system and lower your vehicle's performance.
REALMazdaParts.com has been providing genuine Mazda parts online since 2014. Each OEM component is supported by Mazda’s manufacturer warranty. Use our Mazda VIN Decoder to find the correct part the first time. You can reach out to us online, and our expert team will assist you in finding the ideal replacement fuel pump for your Mazda.