non-tubo 945, 1995

I've been trying to diagnose an intermittent no-start condition. I was pretty sure for most of the winter (this is a third car, so I could let it sit), that the no-start condition was caused by a poor fuel pump. Recently though, the car will occasionally fire right up, idle for 20 minutes, drive around the block, etc, and then occasionally (within an hour) not start, or start, with seemingly random fluctuation.

Today, I noticed that when I turn the key to position II, at first the noise from the trunk(fuel pump) is a low rumbly burble. If I turn the key back and forth a few times in a row (letting the pump wind up each time, without starting the engine), the low burble starts to sound like a higher pitched noise.

So, is this normal, the sign of a failing check valve, or further sign of a failing fuel pump?

Other things I've looked at: most of the relays buzz when I turn the key to II, and the diagnostic system only gives me 1-1-1 on pins 2 and 6 (I think these are the relevant ones).