Fuel Pump Assembly 42021SA070 for Forester Impreza STI WRX 2006-2008

Fuel Pump Assembly 42021SA070 for Forester Impreza STI WRX 2006-2008

This fuel pump is engineered as a direct replacement for the Forester Impreza STI WRX 2006-2008. Manufactured to meet or exceed OEM specifications, it delivers reliable performance in demanding conditions. Each unit is tested for fuel flow, pressure rating, and durability before leaving the factory to ensure consistent quality across every order.

Vehicle Compatibility

Replaces OEM Part Numbers

42021SA070 • 42021SA071 • SP4156H • HP10250 • Application • following • models • 2006-2008 • Subaru • Forester • Turbo2006-2007 • Impreza

Signs You Need a Replacement

If your equipment is showing any of these symptoms, the fuel pump may be the cause:

• Engine cranks but won’t start — The pump may have lost prime or stopped delivering fuel. Check for fuel at the filter outlet before replacing the pump.
• Stalling under load — A weak pump can’t maintain pressure at high demand. The engine runs fine at idle but dies when you put it to work.
• Fuel pressure warning (if equipped) — Modern equipment monitors fuel rail pressure. A low-pressure warning often means the pump is failing.
• Loud whining from fuel system — A failing pump makes a high-pitched whine that gets louder as it warms up. Normal pump noise is a low hum.
• Air in fuel lines — If you see bubbles in the transparent fuel line or the primer bulb won’t stay firm, the pump may be drawing air through a worn seal.
• Excessive return flow — Too much fuel returning to the tank instead of reaching the injectors indicates internal pump wear.

Before You Replace the Pump

Before replacing the pump, check the fuel filter and fuel lines for restrictions. A blocked filter causes the same symptoms as a failing pump on equipment. When installing the new pump, fill it with clean fuel before connecting the lines — this reduces priming time and prevents dry-run damage. After installation, bleed the system fully and check for leaks at all connection points. Replace the fuel filter at the same time as the pump to protect the new unit from debris.

Frequently Asked Questions

Can I cross-reference 42021SA070 with 42021SA071?
Yes. Both 42021SA070 and 42021SA071 are interchangeable OEM numbers for this part. They refer to the same component with the same specifications, just different part number revisions.

My vehicle is a 2006 model – is it covered?
The compatibility range for this part includes 2006-2008. The 2006 model year falls within this range, but verify the engine code and body type match. Mid-year production changes sometimes mean two vehicles from the same model year use different parts.

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