Solution to '97 Outback intermittent/no start
Just a week ago I got the P1507 code so I pulled apart and cleaned the Idle Air Control Valve (IACV) and replaced the MT Neutral Safety Switch (NSS) - see that post under "Engine Light P1507". It ran SO nicely afterwards that I figured my wife should enjoy driving it too. So she drives it a few days and then says it's having trouble starting - it would crank but not fire, or crank for 10+ seconds before starting. Yet it ran beautifully when it did run. (What is it with wives and cars?! Their breakdowns always seem to happen when together, and right after I just fixed her - the car, not the wife.) Here's the symptoms and rundown:
1) After I got her running last week from the P1507 IACV and NSS fix, she ran glassy smooth and very peppy and would literally start and restart any time, anywhere, with barely a flick of the ignition. And never threw any CELs.
2) Then, few days later, she began to crank longer - maybe 3-5 seconds. And after shutdowns, she would start again after about 2-3 second crank. If the car sat longer, the cranking took longer, 10-15 seconds - as if the fuel line bled off or something. After setting overnight once, she started fine the next morning and I could hear the pump whirring when the ignition was turned to "on". But usually after setting overnight would not start the next day.
3) Ultimately, within days the cranking was lasting forever, and she quit starting. I tried intermittently a dozen or two dozen times to start the car. And at this point I could not hear the pump whir when turned to "on". (Please note that I have mentioned "crank" here several times meaning that this never had anything to do with a poor battery or a bad starter.)
4) So I took the fuel pump out (again!) and bench tested it - 12 volts from the charger and she purred like a kitten as usual! So I believed the pump wasn't bad. I reinstalled the pump, turned the key to "on" and could hear it whir again. And the car started again! I also hooked up a hose and glass jar to the fuel line off the fuel filter and she pumped fuel five times during ignition "on" and a full fuel stream when going to full "start". I tested the pressure at ignition "on" and it popped up to 10 PSI. At full start the pressure just blew my gauge hose off spraying fuel all over. Extrapolating a really fast needle spike on the gauge, I would say pressure was well into the 40's.
5) I hooked up the fuel lines again, and she started right up. I then cycled the key off and "on" about 5 times, each time hearing the pump whir - thinking there's nothing wrong now. Until the sixth time when there was silence. And she would not start again.
*** Now certain forums have mentioned a "flat spot" in the pump where the pump is in purgatory like the fields are balanced perfectly neutral or something and the commutator can't spin up. But I didn't believe this was the cause. I believed it was the relay because the pump spun just fine on the bench. I could hear relays clicking in the dash, but I had no proof that wasn't a malfunctioning fuel pump relay. So I had previously purchased a new fuel pump and pump relay expecting to install one or the other - I went for the relay first - it's cheapest. ***
6) Man is that relay ever a Subaru engineering mis-creation - they should have to drive and fix what they build! It was like finding BHO's brain during a colonoscopy - which may be easier. I didn't have to remove the whole dashboard, but I had to cut loose the security alarm box, cut some useless sharp plastic doohickey out of the way, pull several connectors and bend wire harnesses out of the way, to force my hand way up and pinch the green connector tang lose. It hurt. I inserted the new relay into the connector and holding it in my hand checked for the ignition "on" click - it clicked. Since it is impossible to remove the old relay off the fender without yanking out the entire dash, the new one will dangle underneath just fine the rest of its life. But I didn't hear the fuel pump whir.
7) So I pulled the fuel pump (a 3rd time!) and bench tested it. Suddenly, 12 Volts had no effect on the motor. No matter how I twisted and contorted the contacts 30 different ways the motor DID NOT SPIN up. So I installed the new fuel pump and reinstalled all back in the car. I turned the ignition "on" and the pump whirred. *** I went back to the bench, tried the old fuel pump again 10 ways with 12 volts and nothing. I slammed the old motor on the concrete floor and tried 12 volts again - this time it spun up. Almost 100 times thereafter I could not get the motor to repeat its "flat spot" or stall on the bench. ***
8) I put the lower dash, connections, alarm box, and fuel pump cover and seats all back together and tried ignition "on". There was click, and there was whir. And there was fire. The car started instantly - 5 times in a row, and performed just like stock on a test drive.
I am rather satisfied; not as peppy as before, but the fuel pump may just need to break in. I believe the fuel pump was the true solution - the relay was just incidental to diagnosis. And the car still never threw any CEL's. If this was the car's first fuel pump, then the pump went 210K miles - but I am also not the car's first owner.
Good luck with you and yours. God Bless.