Last post on Feb 11, 2013 at 9:01 PM
You are in the Subaru Forester Maintenance & Repair
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Subaru Forester, Electrical, Engine, Fuel System
#8 of 10 Re: Mystery Noise in New Parked 2011 Subaru [trish1920]
Dec 31, 2011 (8:05 am)
Graham had it right except the purpose of the self-check.
He said it was a "fuel system pressure check… to ensure that the fuel system does not have a slow leak… … a high pressure fuel pump delivers a very high volume of fuel to the engine… Pressure cannot be reliably checked when the engine is run…"
He was correct in that the sound is the fuel pump, it is doing a pressure test, and the test cannot be done when the engine is running.
But the check is not testing for liquid gasoline leaking back into the tank through the fuel injection system. The "fuel evaporation leakage" check is testing whether gasoline fumes are leaking into the air from the fuel tank's evaporative emissions control system (vent, charcoal canister, etc.)
#9 of 10 Re: Mystery Noise in New Parked 2011 Subaru [trish1920]
Feb 11, 2013 (8:48 pm)
I have a 2012 Subaru Forester and noticed the same situation tonight. It was about 30 degrees F in the garage. It had been about 5 hours since the car had run. I first noticed the "humming" noise and traced it to under the rear end of the car. I noticed it for several minutes when I heard a "pshhhhhh" and the sound stopped. I'm glad to read that it is a normal feature of the car. Thank you everyone for commenting.
#10 of 10 Re: Mystery Noise in New Parked 2011 Subaru [trish1920]
Feb 11, 2013 (9:01 pm)
You can find information about this on page 9 of your owners manual. It is the fuel evaporation leakage checking system.