Chevy & GMC Vans

Hello Everyone,
Been on the forum for a while but, never had the need to post until now. I've had my Astro for 3 years and put on a lot of miles living, traveling and adventuring in my van with no issues whatsoever. The other day I was running some errands at a local store, van was running fine with no idiot lights on and no running problems, went into the store for about thirty minutes came back out and had this crank no start issue. Called the tow truck and just for curiosity sake we tried to jump it and no go.
Got it home and started to track down the problem. First I checked the spark at the rotor, it was good. Checked for spark at the plugs, good. So, my next link in the chain, fuel. Checked the ECM fuse, checked out good. Went to the fuel pump relay and switched the fuel pump relay with the AC relay (it's the exact same relay) cranked it up but, no start. Checked the current with a multi-meter on the hot pin for the fuel pump relay and got 12.3 volts... good. Used a fused jump wire from pin 87 to 30 at the relay plug cranked again, no start. Next thought was bad fuel pump since I didn't hear the fuel pump running during ignition sequence. Cut an access hole through the floorboard above the fuel pump and checked the wiring there. Noticed that on the four way plug with the ignition on I was getting 5 volts through pin A (The Fuel Level Sensor) but, I was getting no current at all through B (The Fuel Pump Motor Feed) Pin. I rechecked my ground on the multi-meter and tested again, still no current on pin B. Any ideas out there what to check next? I don't have a complete wiring diagram of the full circuit, so I'm kinda navigating by Zen. Any advice or help would be appreciated. I'm wondering if it could just be a loose ground somewhere in the circuit?

I feel your pain.
I do not know it this could be related, but my '98 had 200K o it and the ignition switch felt pretty sloppy when I first brought the van home.
The PO had commented that sometimes it would crank but be reluctant to fire up.
A couple of weeks after arriving home, the van would not start at all. Cranked just fine, and had similar symptoms to what you mention, but I had not done any voltage testing at the fuel pump yet.
I have the three volume shop manual set, so I poured over the electrical diagrams and the feeling kept coming back to an ignition switch issue. Ads i released the ignition key from the crank position to the run position, even though the motor had not fired, there would often be a momentary 'bump' like one cylinder fired, or sometimes two.
I bought a new electrical section of the ignition switch to replace that part, when I began thinking about how the anti-theft circuitry works. There are two small sensors in the ignition key switch body that have to be 'made' when the key is rotated.
Both my original keys were very badly worn, to the point one would not unlock the doors.
I went to the chevy dealer with title in hand, and they made me a brand new key from the factory codes.
A $10 part, and and instant engine start. The ignition has not, since that time, failed me in 5000 miles of starts.
YMMV, but it might be worth the investment if your old key is badly worn.
Good luck!
Rod J
Issaquah, WA

Assuming you found the problem...what did you find?
Something in plain sight, or a very obscure failure?
Just curious
Rod J