Apparent fuel pump operating while engine is OFF. Weird!?

subaru
outback

#1

I’m 1st time owner of a Subaru. This is an automatic 2013 Outback 2.5i Premium with 9,600 miles.

Last Friday and last night (Sun) when the car was parked with no key in the ignition, there was a continuous sound coming from behind the rear left wheel. It sounded like a fuel pump was on.

To stop it, I put the key in the ignition and turned it until all the lights come on without actually cranking the engine. When the key was removed, the sound stopped. The sound seemed to start a couple hours after I parked the car. Both occurred in the evening and there was less than 1/4 tank of gas in the tank.

Since there are 2 commonalities here, I’ll fill up the tank and monitor every 30 min (may not be able to do this when I sleep!). Since it is intermittent, there’s not much the local shop could do except to check if there is any Subaru service bulletin.

I am concerned it was draining the battery last night but this morning it started right away.

I don’t know if this has been happening without my noticing. So is this normal?

Appreciate any insight from the community. Thanks.


#2

What you heard is likely the evaporative emissions system doing a self-test, which is normal. Check your owners manual, and see the link below:


#3

Whew! Thanks so much!
-Anaco


#4

The system can also make noise at the gas cap due to the difference in pressure between tank and atmosphere. My car does it 2013 Rav4. If I loosen the gas cap the hissing happens and the buzz (motor sound) stops. Odd sound until I try that trick. Now I just leave it alone.