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Power loss when warm

I have a 1997 Subaru Outback with 180,000 miles. In January I was driving up the steep hill to the ski lift when it completely lost power. I left it on a side street and walked up. Later that day I managed to get it home and figured it must have had water in the fuel. (We had a long stretch of monsoon-type rain and the car sat with only 1/4 tank of fuel, overnight the temps dropped to well below freezing). A month later I got a new fuel pump in the mail, drained the fuel tank, installed it, and it ran fine. 3 months later I am driving normally for about 15 min, I come to a stop, and when I try to accelerate again, there is no power. I put the engine in park and put my foot on the gas. It revs just fine. I try to drive again, no power. This time, the check engine light flashed and then remained on. I left the car on the side of the road and returned a few hours later. It started just fine. I drove until a few minutes after the car got up to temp. Then I completely lost power…engine still running, just no power. It revved fine in park. The only anomalies are these: while driving I noticed the fuel gauge drawing down faster than usual, and then rising again once the engine was off. It was the first time in a month or so that I had driven fast about 40mph. I was on a bumpy dirt road.

 I am thinking this could be something electrical as it only happens when the car is warm. Perhaps a bad ground somewhere or bad crank position sensor, O2 sensor etc. 
 It could be a worn engine/bad compression...although I imagine I would hear rough running sounds/ misfires etc from the engine or also have difficulty revving in park. 

It’s interesting puzzle and I’m curious to hear your thoughts! Thanks!

Mechanic has to hook up a scanner to retreive the stored code.You might have to tow the car to him or pay him to come see it.

As soon as one experiences a problem like this and while still on the road one can look under the hood for obvious things like cracked or disconnected vacuum lines, low fluids, etc. Next, before throwing parts at the car, is to run a diagnostic scan which any mechanic can do and which many parts stores will do for free, to see if it’s something simple that you can fix. If not obvious or beyond your capabilities, it’s mechanic time. Continuing to drive a car that isn’t running right, and especially if the CEL stays on, can lead to big $$$ engine and/or catalytic converter damage.

When you say no power does that mean it revs but doesn’t go? Is it a stick shift or auto? I’m just thinking maybe a slipping clutch or failing auto trans.

If it’s not transmission then it’s either a fuel problem or electrical problem. Fuel problems aren’t usually intermittent.

Replacing the fuel pump is a lot of time and money. I’m wondering why you thought that was your problem. When a fuel pump fails the engine stops.

The easiest thing to do is free - get your codes checked like Ken said.

Hello! Thanks for the advice. It is an automatic. Replacing the fuel pump worked for the issue in January. I identified it as a fuel issue as the old pump was making a loud whine that it
had not before. The car would start but die after few seconds.

As to the new issue! I went out to the car today and it started right away and sounded fine. It drove a few feet but immediately lost power, even when cold. I towed it back to town. I pulled the CEL codes: misfire on two cylinders. After starting and stalling the engine a couple times the

ATF light blinked, then went out. I will try to pull the ATF codes. There is an audible electrical hum from the top of the engine even when off and the key is out. The only way to get it to stop is to disconnect the battery.
This car may have multiple gremlins.