Hey all--
3rz-fe engine (inline 4) 96 4runner was running great at 268k. I tried to start it next day (cold, but in summer) and there was a second of normal starting sound, then a muffled sound which could have been a backfire or something breaking (just too quiet to tell) and the starting sound changed, became more "free-running" (?) and it won't even fire. (I think the sound change was that it stopped actually combusting.)

I was worried that the timing chain went, but as a friend who is better than I at this stuff pointed out, it's an interference engine and the piston/valve meeting would have made a lot of noise, which didn't happen.

We have tried checking the spark--spark plug number one fires, it looks good and as it showed no fouling, no signs of pre-ignition and no wearing down of the surfaces. The spark occurs at the tail end of the compression (plug out and thumb in the plug hole). You can smell unburnt gas at the tailpipe. We also use starter fluid after the air filter down the tube and you can smell that at the tailpipe as well. But no fire.

We took the distributor off and bumped the engine before putting it back on (yeah, yeah) but got it back to <10 degrees before TDC.

We have spark and we have fuel and even if they're not arriving at exactly the same time there should at least be a backfire, correct? But we got nothing. With starter fluid, even if a whole host of things is wrong there should be some kind of bang somewhere, we thought. The pistons are compressing air and you can smell the fuel at the tailpipe so it's going all the way through. And we can see a spark on the spark plug but there just isn't any fire. Have I left anything out? Thanks for anything you can do.

--We did hear the fuel pump running with the key on. But you can smell fuel at the exhaust pipe anyway, and it's unburnt.

--We checked the distributor also it seems okay visually.

--Another reason I don't think it's the timing chain is because it hasn't been making any noise up to now or having any trouble missing, and timing chains usually tell you they're going to fail for a while, do they not? (At least they did on my old 22RE.)

--There's no sign of water in the oil.

Cheers.

 

Not sure about this motor but on others if the distributor turns then the timing chain/belt is intact.
If you have spark that means the distributor turns (if I'm right).

Not sure how you put a distributor back in and know that it's at <10 without a timing light and using the correct procedure though.

Have you checked for codes?