2013 WRX Fuel Pump: Symptoms, Replacement Guide, and the Best Upgrade
If your 2013 Subaru WRX is cranking but not starting, sputtering under boost, or losing power at high RPM, a failing fuel pump is one of the most likely causes. The good news: replacing the fuel pump on a 2013 WRX is a job most DIY mechanics can handle in a few hours with basic tools, and upgrading to a high-flow pump like the KEMSO 340LPH gives you better reliability and headroom for future power mods at a fraction of the cost of an OEM replacement. This guide covers everything you need to know — symptoms, diagnosis, OEM part numbers, step-by-step replacement, and why the KEMSO pump is the smart choice for WRX owners in the United States.
What Does the Fuel Pump Do on a 2013 WRX?
The 2013 WRX uses a 2.5L turbocharged flat-four engine (EJ255) with electronic fuel injection. The fuel pump is an in-tank electric pump submerged inside the fuel tank. Its job is to deliver gasoline at the correct pressure and volume to the fuel injectors at all times.
Factory fuel injection systems typically require 40 to 60 PSI of fuel pressure. Under full boost, the WRX demands significantly more fuel volume than a naturally aspirated engine. If the pump can't keep up, the engine runs lean — meaning too much air and not enough fuel — which can cause detonation, burned pistons, and catastrophic engine damage.
The pump also relies on the fuel itself for cooling and lubrication. This is why running your tank below a quarter full repeatedly is one of the fastest ways to kill a fuel pump.
OEM Part Numbers for the 2013 WRX Fuel Pump
If you're looking for a direct factory replacement, here are the key part numbers:
- OEM Subaru Part #: 42021VA000
- Supersession: 42021VA030
- Fits: Subaru WRX and STI, 2015–2021 model years (20 vehicle variants across 2 models)
For the 2013 WRX specifically, the pump assembly is often listed under similar part numbers within the same generation. Always verify fitment by VIN before ordering, or use a vehicle lookup tool to confirm compatibility.
Signs Your 2013 WRX Fuel Pump Is Failing
Fuel pumps don't usually fail without warning. Watch for these symptoms:
1. Engine Cranks But Won't Start
This is the classic sign of a dead or dying fuel pump. You hear the starter turning the engine over, but it never fires because no fuel is reaching the injectors. Before replacing the pump, check the fuel pump relay and fuse — a blown fuse is a much cheaper fix.
2. Sputtering or Hesitation Under Boost
If your WRX hesitates, surges, or loses power when you accelerate hard, the pump may not be delivering enough fuel volume under load. This is especially noticeable in third and fourth gear pulls.
3. Whining or Grinding Noise From the Rear
A healthy fuel pump makes a quiet, steady hum when you turn the ignition on. A loud, high-pitched whine or grinding sound from the rear of the car means the pump is struggling. Address this immediately — a pump that seizes completely will leave you stranded.
4. Loss of Power Under Load
Climbing a hill, towing, or aggressive driving causes the engine to cut out or stall because the pump can't keep up with demand.
5. Car Dies Shortly After Starting
Some failing pumps work briefly when cold but stop delivering fuel once the engine warms up.
Important: Do not ignore these symptoms. A failing pump can send metal fragments or plastic debris into your fuel system, damaging injectors and the engine itself.
How Long Does a 2013 WRX Fuel Pump Last?
The average lifespan of a modern electric fuel pump is around 100,000 to 150,000 miles. However, several factors can shorten that:
- Running low on fuel regularly: The pump overheats because fuel cools and lubricates it.
- Clogged fuel filter: Forces the pump to work harder, drawing more current and generating more heat.
- Contaminated fuel: Dirt, rust, and water damage internal components.
- Old, degraded fuel: Can gum up the pump motor.
If your 2013 WRX is approaching or past 100,000 miles and still on the original pump, it's worth replacing it before it fails completely.
Tools and Parts You Need
Before you start, gather everything. Running to the auto parts store mid-job wastes time.
Tools:
- Socket set with extensions (10mm, 12mm, 13mm, 14mm)
- Flathead and Phillips screwdrivers
- Pry bar or trim removal tools
- Floor jack and jack stands
- Gasoline-safe catch pan (minimum 5-gallon capacity)
- Safety glasses and nitrile gloves
- Fire extinguisher (Class B rated)
- Shop towels
- Flashlight or headlamp
Parts:
- New fuel pump assembly (pump module)
- New fuel filter (always replace at the same time)
- New fuel pump strainer (usually included with the pump)
- New O-rings and seal gaskets
- High-quality hose clamps
- Dielectric grease for electrical connections
Step-by-Step: Replacing the Fuel Pump on a 2013 WRX
The 2013 WRX uses an access panel under the rear seat method, which is much easier than dropping the entire fuel tank. Here's the process:
Step 1: Relieve Fuel System Pressure
Start the engine, then pull the fuel pump relay or fuse from the fuse box. Let the engine run until it stalls. Turn the ignition off. This depressurizes the fuel lines so gasoline doesn't spray when you disconnect them.
Step 2: Disconnect the Battery
Remove the negative battery cable before doing any work near the fuel tank or electrical components.
Step 3: Work in a Well-Ventilated Area
Work outdoors if possible. Never smoke or use anything that creates a spark near the work area.
Step 4: Access the Fuel Pump
Fold down the rear seat and remove the access panel cover. You'll see the top of the fuel tank and the pump module.
Step 5: Disconnect Lines and Electrical Connectors
Label everything with tape or a marker. Disconnect the fuel supply line, return line (if equipped), and electrical connector.
Step 6: Remove the Old Pump Assembly
Unscrew the retaining ring or bolts holding the pump module in place. Carefully lift the pump out of the tank. Have rags ready — some fuel will drip.
Step 7: Install the New Pump
Install the new pump assembly with a new gasket and O-rings. Reconnect the lines and electrical connector. Reinstall the access panel.
Step 8: Restore Power and Test
Reconnect the battery. Turn the ignition on (don't start the engine) and listen for the pump to prime. Check for leaks. Then start the engine and let it idle.
Why Upgrade to a KEMSO Fuel Pump?
When it's time to replace your 2013 WRX fuel pump, you have two choices: buy another OEM pump or upgrade to a high-performance aftermarket unit. For most WRX owners, the KEMSO 340LPH High Performance Fuel Pump is the better option.
Here's why:
1. Higher Flow Rate
The KEMSO 340LPH pump flows 340 liters per hour — significantly more than the factory pump. This gives you headroom for future modifications like a bigger turbo, E85 conversion, or higher boost levels.
2. OEM Replacement Fit
KEMSO pumps are engineered to meet or exceed OEM specifications and fit directly into the factory housing without modification. Their website includes a vehicle lookup tool covering over 4,000 models from 1990 to 2024.
3. Built for Performance
KEMSO pumps use brushless motor designs in many applications, which reduce current draw, improve durability, and run quieter than traditional brush-style pumps. They handle ethanol blends up to E85 without issue.
4. Lifetime Warranty
Every KEMSO fuel pump comes with a lifetime warranty — a level of confidence most competitors don't offer. Their pumps maintain 98% efficiency even after 15,000 hours of use.
5. Proven in Real-World Conditions
Professional racing teams like Gridline Motorsports and drift teams like Bloodshed Motorsports have standardized on KEMSO pumps after experiencing fuel starvation issues with other brands.
6. Affordable Price
At $79.98, the KEMSO 340LPH pump costs a fraction of what dealerships charge for an OEM replacement, and it outperforms the factory unit.
Ready to upgrade? Visit https://www.kemsoracing.com/ to find the exact KEMSO fuel pump for your 2013 Subaru WRX. Their fitment guide makes it easy to confirm compatibility before you buy.
Maintenance Tips to Make Your New Pump Last
Once you've installed a new pump, follow these habits to get the most life out of it:
1. Keep Your Tank Above a Quarter Full
The fuel in your tank acts as a coolant for the pump. Running low consistently causes the pump to overheat and wear out faster.
2. Replace the Fuel Filter on Schedule
Most manufacturers recommend replacing the fuel filter every 30,000 to 50,000 miles. If you drive in dusty conditions or stop-and-go traffic, shorten that interval to 15,000 to 20,000 miles.
3. Use High-Quality Fuel
Top-tier gasoline contains detergent additives that prevent varnish and deposit buildup inside the pump.
4. Listen for Unusual Noises
A whining or buzzing sound from the rear of the car is an early warning sign. Get it checked before the pump fails completely.
5. Maintain the Electrical System
A weak battery or corroded wiring can cause the pump to operate at reduced voltage, making it work harder and run hotter.
6. Manage Moisture
Condensation forms inside the tank as temperatures fluctuate. Keep the tank relatively full to minimize air space and moisture buildup.
Frequently Asked Questions
Q: Will a KEMSO 340LPH pump work with my stock 2013 WRX?
Yes. The KEMSO pump is designed as an OEM replacement and works with the factory fuel system. No tuning is required for a stock application, though a tune is recommended if you've added other performance mods.
Q: Do I need a fuel pressure regulator with an upgraded pump?
Most EFI systems operate at 43–58 PSI. The 2013 WRX has a factory fuel pressure regulator. For stock or mildly modified setups, the factory regulator is sufficient. For big power builds, an aftermarket regulator is recommended.
Q: How long does the replacement take?
Plan for 4 to 6 hours if you're working in your driveway with basic tools. The access panel method on the WRX makes it faster than vehicles that require dropping the fuel tank.
Q: Can I drive with a failing fuel pump?
No. A failing pump can leave you stranded at any moment. Worse, it can send debris into your injectors and engine, causing thousands of dollars in damage.
Q: What's the best fuel pump brand for a 2013 WRX?
For most owners, the Walbro 255LPH is a popular budget option. However, the KEMSO 340LPH offers higher flow, a lifetime warranty, and better value for the price. For builds over 500 WHP, a dual pump setup is recommended.
Final Thoughts
A failing fuel pump is one of those problems you can't ignore. The symptoms — hard starting, sputtering under boost, loss of power — only get worse, and the risk of engine damage grows every time you drive.
The good news is that replacing the pump on a 2013 WRX is a manageable DIY job, and upgrading to a KEMSO 340LPH High Performance Fuel Pump gives you better flow, better reliability, and a lifetime warranty for less than the cost of a factory replacement.
Don't wait until your WRX leaves you stranded on the side of the road. Check your symptoms, confirm the diagnosis, and upgrade your fuel system before it fails.
Visit https://www.kemsoracing.com/ today to find the right KEMSO fuel pump for your 2013 Subaru WRX.