My truck surprised me by almost failing to start last night, and I don't have a clue why. My battery had a good charge, my starter cranked, and the engine sounded like it was cranking faster than normal, as though it weren't running into any resistance from compression. After cranking it for about 15 seconds, I gave it a rest for a few minutes and tried again. Same thing, but this time I could hear the engine slow down and turn over now and then, and then with a puff of blue smoke, it was running.

The 5VZ-FE engine has just over 100k on it, and it's been pampered (besides the wheelin'). Doesn't burn or leak any oil. Starts easily every time, except last night. Even this morning it started as easily as ever.

It's time to change the spark plugs, but it the old plugs were fouled or worn out, I'd think that I'd have this problem more consistently.

Any ideas about what happened?

 

Did you change your timing belt lately? or is it due?
I'd check the timing marks just to make sure it wasn't jumping.

 

That got changed about 8k ago. Don't think it's jumping, but if this happens again, I'll check.

 

Very interesting issue....before I bought my 4runner, I had a 2001 Avalon with the 3.0 motor....I discovered by accident that when starting the car, if I let go of the key prior to the engine starting it would do this. This car was also very pampered and I never had any problems with it other than this occassionally. When it did it a second time, I floored the accelerator and it started in about 4 to 5 seconds. I also had this very same thing happen on a friends 1999 Honda that I was working on.... What I am guessing is that somehow the motor is flooding under certain conditions. Your sympton sounds similar but different - I bet if it happens again if you floor it when trying to start, it would (start).