hi,
I had a problem with my Express. It was raining that day. I turn the key, all control lights turn on, I try to crank the engine and there's only click, click. Asked the guy next door to give me a boost - started at first turn of the starter. Got to the job site, turned engine off and it wouldn't start after - just clicks. Got taxi driver with booster cables - we couldn't start it. Gave up and went home. Next day got there with my other car and the van started at 1st turn without any help from cables. So far so good. also noticed that voltmeter needle started to bounce a little when driving.
So I'd appreciate any insight on the issue. Thanks

 

Could be a few diff things.
Bad starter relay.
Bad starter.
Bad engine ground.
Bad battery.
Start with the cheapest first. Load test the batt. Swap the starter and fuel relay....they are identical and side by side. Check all grounds and cables.
If those don't improve things, I would replace the starter. Or run power direct to starter motor from batt and see if it cranks.....
Hope that helps.