Q: Car won't start after fuel pump installation 2004 Subaru WRX/STi Hybrid

asked by on

After I installed a new 320 AEM fuel pump, the car won't start properly. The car WILL start say after leaving it overnight or, after it's been completely off for over an hour. When the car does start, it feels like it loses power or combustion. I have to rev it up to 300 rpms for half a minute and the under power symptom stops. It didn't do this with the stock Walbro pump. Though, I did notice the fuel pump sock is quite smaller, I've read other people replacing it with this AEM pump without issues before. I need to install the fuel injectors too, as recommended by my tune guy before getting it Protuned this Wednesday.

Please help!

My car has 155000 miles.
My car has a manual transmission.

If the hard starting issue began immediately after the pump install, a possibility is the fuel delivery (pressure and volume) characteristics of the new pump are far enough off stock (or your just prior pump), that the engine either floods, or delivery is inadequate (you mention a smaller pick up), at least during start up. Another possibility is a defective pump or an installation issue, overlooked restriction in the lines and so forth. if you request a no/hard starting - engine diagnostic the responding certified mechanic will take a look at what you have and pinpoint the cause. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Car won't start after fuel pump installation 2004 Subaru WRX/STi Hybrid

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Squealing and clicking noise from back part of the car but only when moving forward

Hello, thank you for writing in. The first step is to definitively determine if the noise happens when the vehicle is moving (and it is brake or wheel related), or if the noise happens constantly when the vehicle is running....

Q: Codes po102 103 113

Hi there: It's very difficult to tell you where to start if we don't know what type of troubles or symptoms you're experiencing. A professional mechanic typically will download OBD-II trouble codes first, then test drive or communicate with the...

Q: Car floods, have to pull fuel pump fuse to start

Hello. If your car is throwing over 20 codes, then I would stop driving the vehicle and have it serviced as soon as possible. That many codes at once is a potential indicator of a serious issue, even if the...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.