I have an '88 Cavalier 2.8 which ran perfectly normal until I shut it off and when I went to start it 2 hours later it just cranks and cranks. I just towed it home and haven't looked at it yet. The engine has unknown miles, as it's not original. I am going to check a few things first, like the crank sensor, which on these are known to leach oil from the crankcase through the sensor and onto the prongs the harness plugs onto, and cause a no-start, and can be blasted off with electronic cleaner periodically (per a TSB on the subject) to avoid that problem. So I routinely do that every time I change the oil, but in this case, that wasn't all that long ago, so I'm thinking that's not the problem. But it acts the same.
In my experience, when a timing gear goes out it acts just like that (runs normal, then suddenly won't start). How do you determine the position of the timing gear on these (it is an MPFI with no distributor). I can't tell by the way it cranks if the valve timing is good or bad
-- it cranks plenty fast, but I don't know if it's faster than usual, since it just pops right off normally.
Also, any other time I've had a timing gear go bad, IIRC the engine was firing at weird times and trying to run backwards. But they were all distributor equipped. This one doesn't do that, but could that be because it is crank-triggered? I can't tell if it's firing at all, and I didn't smell gasoline while trying to start it. It just cranks and cranks.