I believe I know the answers I will get but just wanted to hear then anyway,
98 astro, bought it with a suposed dead fuel pump, started w/starting fluid.
got it home and no sound from the tank, checked and there was power to the pump, pulled the filter, clogged very bad, pulled the tank/pump, put power to the pump nothing, smacked the pump (not too hard) pump jumps to life.
now the question, should I trust the pump?
if we were talking about a $50.00or even a $100.00 part there would be no question, but as most know these damn things run to the tune of around $400.00.
I would like to test it in liquid for a couple of hours but I dont want to submerge it in water and ruin it if it is good, and there is no way im gonna run it in a bucket of fuel, "I do not wish to blow up my home or die",
If anyone knows of a way to test with a meter im all ears and would be greatfull,
I ran it dry for 1 min 30 sec the motor started getting warm and I heard a slight variation in the motor hum, but I dont think this is a very good test since everyone knows these things need liquid to run through them for cooling.
I figure the clogged fuel filter and it being run low on gas stopped the pump
but I dont get why it would start again with a smack and seem to run so smooth after it was I guess siezed, bad spot in the armature? I pulsed power to it a good hundred times to get it to stop in the "bad spot" again so I could see it was bad but it jumps to life every time I put power to it.
anybody with knowledge on these things? I'd be greatfull.

I wouldn't trust it. Get a new one.

I wouldn't trust it to start again with even a hammer blow.

You can get the pump separate from the sending unit, if you shop around a bit. A replacement pump is only about $100, versus the $400 for the whole in-tank unit. However, if you DO replace only the pump, check all four of the connectors very closely for signs of resistive heating. I believe the EP381 is the correct pump, but make certain before ordering one.