Well, I can't explain that (ignition/tuneup)

I don't *think* I need help, but I'd feel better if I could come up with a logical explanation for what just happened... Long story short, my engine is making a noise I don't like, I would like to be able to pull spark plug wires one by one to rule out a rod bearing before driving it too far, I found that I had what appeared to be original plug wires and plugs (82K miles) and I simply could not pull the wires off the plugs without destroying them. So I ordered a tune-up kit from Quadratec (actually cheaper than Vatozone) but bought the Champion plugs from NAPA because everyone says to use those. All well and good so far. Tuneup kit came in yesterday, but I didn't have time to put it in because I had to go vote, got home today and got at it. Replaced cap, rotor, plugs and wires. I must have one strong coil because I didn't have a gauge big enough on my set to measure the gap on the old plugs! (ran fine though.) Anyway, finished up just as it got dark, hit the key, cranks but no start. I could also hear something loud from the rear of the vehicle (fuel pump?) with the key on but not cranking. Tried it a couple times, no go. Came inside and looked up the firing order (hey, I'm used to 1-8-4-3-6-5-7-2, what can I say) verified that I got it right, pushed on all connections and didn't find any loose ones, tried again, fired right up and purred like a big four liter kitten.

Can anyone come up with a reasonable explanation as to why that happened, and what the noise was? (fuel pump?) Last time I started it was Monday after work, I drove it up the street to the store, it's sat that long before though and always fired right up.

For the time being, I guess tomorrow night I'll neaten up the plug wire routing (I took pics, but it's too dark to see right now) and call it done, but this was supposed to be my trust implicitly/drive anywhere vehicle...

You probably heard the fuel pump priming when you turned on the ignition. The noise would be a ~2 second whine. Many fuel pumps whine, new(my 255 walbro) and old, so the noise doesn't necessary mean it is on it's way out, but if you notice a change, be prepared.

I'm used to that from my old VW's (actually it's more like 5 sec there, and one of my GTIs had a bad accumulator so I was actually used to listening for the whine to stop before engaging the starter) it was louder than that and didn't cut off. Also didn't notice it happening again after it started. It did sound like it might have been a fuel pump, but more like one of those old, loud, rattly cube shaped electric deals that they used to sell for carbureted cars... I'm puzzled... guess I will just pay attention for any unusual noises/behaviors. Not that I'm not already, being still in the "getting to know you" stage with this one. (even though I've already put a whole mess of miles on it in the last month, including a couple 5 hour straight shifts behind the wheel due to a funeral and some bad weather.)

Check connection/test CKP. Your crank position sensor connector is a 3-pin connector driver-side near the rear of the head. I would disconnect, reconnect and try and start again. They are about 50$ at your local parts store, I believe.
It is a common thing for XJ/ZJ's that crank but not start.

Fuel pump might have a motor brush going bad, and locked up, and for now unlocked? Be ready for problems maybe? Or the check valve may have stuck and unstuck in the fuel pump?

year?

I didn't clean off the cap/rotor, is it possible that there was some kind of insulating coating on the button and/or rotor itself that needed a few revolutions to wear off? Doesn't seem likely but that's the best explanation I can come up with.

I'll keep CKP in the back of my head but I don't need to start making projects for myself unless necessary... bad enough that I "had" to change plugs/wires before I could even troubleshoot another issue. It appears to be running now, so I'm kind of back to where I was last week