I had a 400 ISL in a Monaco and changed the filters once a year for ten years and never liked putting them on dry, at least not the primary. The two times I tried, it didn't start. To me, it's not worth the aggravation. I like to put the primary filter on after filling it. Use your thumb or a plug to block the center hole and fill around the outer edges. Install the filter and start the coach. Once you know it's running properly, shut it off and install the secondary filter.
My new coach has a hand primer, so it's a little different.
