My 89 Four Winns with an OMC Cobra out drive had the same problem last Fall on the last trip out. Propped up the stern for the winter in the rack and many thoughts incuding failed pump, low fluid etc over the winter.
Simple problem...drive stuck in the down position......bad ground connection. Corrosion was the culprit. Simple 5 min. fix by Steve P
at Fay's this spring. He is great. Now he gets a Turbo Coffee every time I see him!
Check for power going to pump and you may find none at one point where corrosion is the problem. I understand this can be a common problem if the boat is older.