Mysterious problem! Expert advice needed

[Jamil1]

This is the second time my 89 325iS has done this: first drive of the day, starts fine, go down to the gas station about 3 min/ away. Get gas, then when I go to start up again it spins and spins and every once in a while it clunks hard and stops spinning, almost like the timing is off... I changed the timing belt about 3K miles ago, no problems, runs fine, idles fine, accelerates fine, just this weird no start...spins and spins, almost wants to start, I can hear it firing but if I let off the key it dies. Any ideas on what could be happening? Could the belt be 1 tooth off? Doesn't seem like it would start fine and run fine otherwise??? Its only happened a couple of times recently but its got me worried. The "clunk" when its spinning sounds almost painful~
OK, so I've posted this before under a different title, but, forgive me while I whine, I realize that the title didn't elicit much attention, but am kinda bummed when a title like "suspension upgrade" gets over 350 hits and 15 responses....
BTW, I really enjoy looking at others' cars and wish I had more time to work on mine...

[thejlevie]

The clunk when the starter is spinning the engine sounds like a cylinder firing at the wrong time. The cause of that could be a bad timing reference sensor or a bad DME. Recheck the cam timing just be be sure it isn't off, which will cause difficulty starting the engine.

[T77911S]

im not expert, but,

when you first said it spins and spins, i first thought of the starter not engaging and the starter jsut spins, and the clunking was something with the starter. could you have 2 problems? one with the starter and one a hard/no start problem? like the starter disengaging then trying to reengage the flywheel.

[Jamil1]

Jim, aloha and thanks for the input! I'll run the DME checks you wrote up in another thread and also check the cam timing. Is it possible for it to be hard to start but have it run fine? Wouldn't these symptoms which sound like timing related also affect the running? When you say "timing reference sensor", is that the crank sensor, over the toothed ring at the front of the engine? Is there a resistance test or some such that can be performed to determine its condition?
T77911S, thanks for your input as well! I don't really think that it is starter related as the engine spins over quite smoothly and it doesn't sound like the solenoid is cutting in and out

[Honolulu]

Jamil1, use the search to find the CPS resistance value, then ohm the sensor at the connector up on the left side near the diagnostic plug/port (on my '90 anyway that's where it is).

The CPS can go intermittent, then die leaving you stranded, DAMHIK.

Rare to see anyone from Laupahoehoe. I grew up (sorta) in Piihonua but live in Kaimuki now.