dude, Your valve must be loose.
Try to tighten the valave that leaks.
I have a SEA EAGLE boat that came
with a wrench to keep the valves closed tight. Also,
try cleaning the threads-they might be dirty..ED

thanks for the speedy reply. don't know how the valve got loose sitting in storage but will try to tighten. will probably have to make the tool,

I agree - tighten the valve, check for missing washers, seals, etc. make sure cap is tight also.

What type of Zodiac? Is it a bonafide Zodiac, or another make of inflatable?

In addition to the responses above, try this too:

1. Fully inflate the boat (no need to do the keel) Make sure it's good and pumped up!

2. Confirm all the caps are secured. NOTE: Air leaking with the caps off is perfectly normal. The cap is what makes the valve air-tight.

3. Now, get some soapy water and start slathering the tubeset. Pay special attention to the caps & valves.

Do you get any bubbles anywhere?