No start - Cranks for 3 seconds then stops cranking

[RussMcB]

I did a bit of searching, and haven't heard of this particular symptom, so I thought I'd post here.

Symptom: Car cranks strongly for exactly 3 seconds, then abruptly stops cranking. It is very repeatable. It's done this about 12 times in a row now.

I've just reinstalled the plenum, so the problem is very likely something I did wrong while putting it together. Tonight I'll probably take it back off to look for the problem, but thought I'd go ahead and post here to get any thoughts.

A guess: It seems like the starter is cranking well, and then the ECU doesn't get a signal it expects, so it shuts down.

I had the plenum off to troubleshoot a big vacuum leak. Before I put it back on I made two changes (both related to vacuum lines):

1) I removed the larger, evap hard lines. I left the solenoid plugged in. I plugged the port under the plenum, but left the hose going to the back of the car unplugged.

2) I removed the smaller hard lines from under the plenum and routed new rubber lines from a plenum side port, through the check valve and then to the HVAC and cruise control.

I don't think my no-start is due to the vacuum line changes, but could be wrong.

When installing the plenum I was pretty careful with electrical plugs and all, but could have screwed something up.

Thanks.

PS. According to my aftermarket gauge, I have good fuel pressure. I do not have any codes. I have not checked a plug wire for spark yet. Battery has a full charge. I forgot to look at the tach to see if it showed RPMs during cranking. I do have (what I believe are the normal) lights on in the dash and information center screens.