So if all you are concerned about is the % I would suggest checking the Meta-Characters allowed in your URLs as if this character is not allowed it will be blocked. By default all Meta-Characters are blocked as a part of the URL, Parameter Names and Parameter Values so you would have to go into each area to allow the characters you want.
As far as running a query on the ASM itself I am not sure, but you could just send the requested through the ASM with a browser and see if you get a block page, if you get a response from the web server of any kind it made it through the ASM.
Mike
Nimbostratus