Livewell problem

This is a great message board. I've been lurking since June of 2004, and have picked up a lot of tips. Now I've got a question , for which there are probably as many answers as message readers
I bought a used 16' 1986 Monarch bass boat, that's in really good shape, engine (90 hp Merc) runs good, and rides great ! Problem is, it's got 2 livewells, and I can't get either one to fill. I've had the pump out, checked it out in a bucket of water, and it shoots water out big time. The valves on the aeriator tubes were corroded (or old) enough to be stuck....... couldn't tell whether on or off.... so I replaced the rear livewell aeriator tube and valve. The front one is "just" out of reach , under the deck, so won't change it out, until I find out what the real problem is. I've re-installed the pump to the pickup, and when I run a garden hose into it, I am able to pump water into the livewells, but at the lake, I get nothing up to the wells. Could it be my pump, or is it an "airlock", or should I look for some other solution ?

Dennis