Does anybody have any idea why the solenoid would engage the starter motor and then cut-out after only a couple of seconds?

Low battery voltage will do that.

sounds like an intermittant power or ground loss. Is it shuting off or dis engaging? When it disengages does it stop or do you hear the starter teeth meshing with the flywheel? If thats the case could be a weak bendix spring.

Then again, the bendix may be taking a doo-doo(tech term).
If the starter is engaging the flywheel, but then it quits turning the flywheel, it's prolly the bendix itself. They work like a sprag, or one-way clutch, meaning they lock in one direction, and free-wheel in the other. If the bedix is failing, it may not have enough "lock" to keep spinning the engine.
You may also have a few bad teeth on the flywheel, that could cause the exact same problem.
IF, however, the starter stops spinning while you're trying to start it, it could be a connection, or the solenoid, as was posted above.

As far as the wiring to the solenoid, the big red wire(from the batt.) goes to the center terminal, and the purple wire will go to the terminal closest to the engine block. There are other wires that also go on these two terminals, but these two are the only ones that actually crank the engine.
I'll send ya a wiring diagram, just in case.

Thanks guys. I can hear the bendix spin after it disengages the flywheel. The diagram in the shop manual shows two wires going to the post on the front of the solenoid closest to the block, ground (black) from bracket to the frame cross member and one from the wiring harness mounting to a bolt on the back of the solenoid/starter.

You should have a yellow wire connected to the terminal on the outside...the one farthest away from the engine. This is the 12v supply to the coil, so the coil will have a full 12v while cranking.
The purple wire is from the ignition switch "Start".
The red wire(s) go to the fuse box, and other 12v supply items, such as the amp gauge, headlight switch, and horn relay.


                                         


[QUOTE=Vettenut]I will check to be sure the 1) purple wire is the other one I connected to the solenoid terminal with the positive cable from the battery and 2) that I actually connected one to the back (toward the passenger compartment) instead of on the second post on the front of the solenoid.
[/QUOTE]

I just re-read this...the purple wire should be by itself on the terminal closest to the engine block , NOT on the center terminal with the batt. cable. I don't see how you could possibly get it on there(center terminal) anyway, as the eyelet is too small to fit on the center terminal, but...
I'll see if I can get under mine to get a decent photo...it will prolly be tomorrow tho...
I think, by your description, that it is the bendix...Adams' Apple2008-05-13 19:59:59

Correct Joel. I got back under it last night after you sent the separate wiring diagram and it is wired correctly (re-checking against the color diagram above). You could not put the purple wire on the battery terminal on the solenoid, too big. I'm going to get a new starter motor and re-build the original if I don't have a wire crossed. I'm leaning towared the bendix as the culprit.