I drove about 2000 trouble-free miles including some longer road-trips. Then, a few days ago I went on a road-trip and when I arrived in Vegas (hot, middle of day -- not sure if this is a factor) the engine started cutting out on the freeway. Seemed to be worse under load (hill) and the power really cut-out as I was starting through an intersection and I coasted to the side of the road. No warning lights flashed on the dash (and haven't any other time). I restarted it a few minutes later and it drove great.
The next day the auto parts guy suggested a new fuel filter, which I put in. I drove about 200 miles through Death Valley (110+ degrees) with no problems, but then on a hill it started cutting out again, and got bad enough that I had to pull over. After letting it sit off for a few minutes, it was difficult to start, but ran fairly well (not perfectly) for the next 40 miles or so.
I checked it into a repair shop in Lone Pine CA and they were able to get it to cut out, but said the computer did not indicate any problems, and the history didn't either. Said it could be one of a dozen things (fuel pump, lose wire to fuel pump, etc, etc, etc), and that they could throw parts at it but it could cost $2k to hit the right part.
I picked-up the car, filled it up and drove about 200 trouble-free miles back through Death Valley (115+ degrees), but just outside of Vegas it started acting-up. As usual, it started with a very slight cut in power, and I could induce a full-blown series of power cuts by pushing on the accelerator hard. I'd noticed that the problem seemed to happen when fuel was below a 1/2 tank, so I stopped and filled up and the problem went away and I drove another 20 miles to Vegas.
Subaru service person in Vegas said it might be a fuel pump, and that she'd once seen one with a problem that was related to fuel level, but that it was not the norm. Called Subaru service guy in Salt Lake and he floated the idea of a dirty tank or a crack on the fuel assembly that sucked air below a certain fuel level.
I drove north toward St. George and about 100 miles later I was going up a grade and the symptoms returned. Got so bad I had to pull over and stop. Started up again after a few minutes and it ran great for about 15 miles but then returned and I barely limped off the freeway and made it to a gas pump. Put in 6 gallons and it ran perfectly for another 80 miles where I stopped for the night.
After hours of thinking about it, a lot of Google searches, and talking with some friends, I'm thinking it could be the fuel pump, or possibly a bad o-ring/seal or crack in the fuel assembly that is letting in air when the fuel drops to a certain level.
Edited by Jimbo67, 20 June 2012 - 12:48 AM.