We're having an ongoing issue with our beloved 1994 Civic Hatchback. It's always been super-reliable. And I'll mention that it's been running on three cylinders without issue for a few years now, since (we suspect) a mechanic during an oil change spilled oil and wasn't honest about exactly what he did.

We don't drive much, a few times a week and live in a smaller town. In November 2022, we were in a larger city and had made stops at a number of places without issue. Suddenly when we started the car at Wal-Mart, it wouldn't start. It turned over, obviously wanted to start, but couldn't. After about 15 minutes of waiting, it started fine. We drove home and didn't know what to think. But the next day it started normally again.

About two weeks later, we were doing errands in town. It was fine until one stop, when the same issue occurred. After about 15 minutes, it started fine and we continued, but didn't turn off the engine until we got home. The next time we drove it, it started fine.

We did some reading and decided to change the fuel filter. There were issues getting it on properly for whatever reason even though hubby'd done this repair on a few other occasions. But ultimately it was on and not leaking. The car was fine until just prior to Xmas, when the same thing happened at the grocery store. It ended up starting, but this time, we took it to a local mechanic. The mechanic looked at it the next day, but it started up right away even in -24 weather and purred like a kitten (according to him) and since it wasn't misbehaving, he had zero idea what was wrong. He suggested some gas line antifreeze, in case there was moisture in the gas line. And we got that.

And it was fine until yesterday, January 23. When it started and was idling, I thought I heard a high-pitched sound I didn't recall hearing before, but I wasn't sure. We were at the grocery store again and when leaving, couldn't get it started. It turned over, all lights are fine, everything electrical seemed fine, but no starting. By coincidence, a man came by who was in the parking lot who purported to be a mechanic. He was convinced it was the timing belt. Regardless, it wouldn't start after many attempts. The battery was starting to run down. We gave it one last try before calling a tow truck and that last try resulted in really loud backfire from the exhaust pipe. We towed it home, which is where it is currently.

We have a video (20 seconds) of the engine when it didn't start yesterday. I'm hoping that someone who watches it might hear something that will give us ideas on what's up with our Civic. You should be able to watch this without a Dropbox account: https://www.dropbox.com/s/fbvn581p2l...02023.mp4?dl=0

I phoned the mechanic who looked at it previously and he suggested it could be the alternator due to the high-pitched sound. I'm guessing he means the alternator belt. I'm also wondering still about the fuel filter. It seems to be fine now, but I'm insecure about it because it was problematic to install. Or if maybe it's the fuel pump itself, which we've changed before on the Civic. This car has needed very little over the years we've had it. We want to fix it, but we're looking for some idea of what it could be. The mechanic we go to isn't equipped to deal with a number of general mechanical problems, he's primarily brakes and mufflers. And our prior mechanic closed. We have to take it to a new mechanic in town who may or may not deal a lot with older cars and feel weird doing that without any ideas whatsoever as to what it might be.

Any help would be greatly appreciated.