96 legacy intermittent starting issue

[b1pig]

Hello, all.

The wife bought a "new" 96 Legacy L wagon a little over a month ago. 2.2, AWD, auto. We had it about a week at the time that I had to drive out of town. Right after we drove it home the first night, CEL came on. I pulled the code for the knock sensor. reset, and it came right back. been on since.... No biggie, i think.

When I went out of town, it was hot. (june in Georgia) While in Forsyth for the week, the car had an intermittent hot start problem. It would crank over and not fire. I had no shop manual, and I couldnt locate the fuel pressure test port before it fired the last time. Only did it while hot... and within 15-30 minutes of parking.

I shook all parts of the wiring harness, which really didnt help. I didnt have a helping hand to try and verify if the issue was spark or fuel related.... but it always did fire up. it would take anywhere from 5 tries to 10 minutes of trying, checking and trying. The last time it did it, when it actually fired up, it sputtered like it was just getting fuel.

That was the symptom... here's the question(s).
Can any of you guys tell me if there is a known issue that would cause an intermittent starting problem?(crank over - not fire) How about a vapor-lock issue? (rare with, I know) will the knock sensor contribute or cause this? The last time it did this, it was close to 100 degrees. However, the last time this occured, was the third of June, and the temp has been a tad over 100 since, and the hot-start problem hasnot resurfaced.

I'm hoping this is not symptom of a failing fuel pump or something. Any tips will be greatly appreciated. Have shop manual.. have tools... need inside info.

[Manarius]

Most likely it's the Coolant Temp. Sensor. It's cheap so I'd start there. A failing/broken one frequently causes a hot start problem.

[napphappy]

And, there is no fuel pressure test port.

[b1pig]

since I didn't have the shop manual as an aid, and the fact that it was getting dark, I never located it before it finally started up. What led me to believe it was a possible fuel delivery problem was the way it actually came to life. almost like it was just getting a trickle of fuel, and then once it fired it sputtered a second and then caught.

Since that week, the hot start problem has not resurfaced. Both the wife and I have driven it with no problems.

manarius... so if the ECU isn't getting a reading from the temp sensor... or a reading outside the "limits"... then the ECU will not let the engine run? if so... that's pretty interesting.

[Manarius]

manarius... so if the ECU isn't getting a reading from the temp sensor... or a reading outside the "limits"... then the ECU will not let the engine run? if so... that's pretty interesting.

Um, I think it either works like you described, or it works such that the ECU isn't getting a reading (or a correct one) and doesn't know what to do about adjusting the A/F mixture for start up.

[gt2.5turbo]

when my sensor was bad it wouldnt not start all the time just on reallly hot days i would have to sit and crank on it for a few seconds for it to start. replaced the sensor and it starts like a champ now

[b1pig]

when my sensor was bad it wouldnt not start all the time just on reallly hot days i would have to sit and crank on it for a few seconds for it to start. replaced the sensor and it starts like a champ now

So yours was the coolant temp sensor, too?

Guys, thanks.
I posted this SAME question on two other Subaru sites with no response. That helps me out a bunch.