I appreciate the various suggestions I’ve gotten on this thread. Here’s how it shook out... A title for what follows could be “Changing CAT C9 fuel filters for dummies”
Despite the official CAT stance that fuel filters should be installed dry and my fear about breaking this rule, the thought of leaving the primary dry seemed even scarier (since I have not yet done the 206-5756 priming pump kit mod).
So I chose a combo wet-dry approach to changing my 2 fuel filters. That is, I filled the primary and did not fill the secondary. My reasoning was that a) using a rubber stopper (purchased at Lowe’s and also available at ACE Hardware stores) allows filling the primary filter via the outer (dirty side) holes and b) if I drove the coach after the primary filter change, any contamination I introduced in changing the primary would be caught by the old secondary filter before I then changed it. Here are a few details and observations from my rookie point of view:
I cut a hole in a small cardboard box to hold the new primary filter securely upright, plugged the center hole with the clean new rubber stopper, then slowly poured unfiltered fuel into the ring of small holes around the plug. As I did so, I could see the inner chamber of the new filter filling with filtered fuel. In fact, since I’d used the valve to check for water in the old primary (out of curiosity) before unscrewing it, the new filter ended up having more fuel in it than the old one. This was a confidence builder.
Then screwed the new filter on per instructions on the filter.
The engine started easily and kept running and seemed smooth but the check engine light fluttered on and off for about 15 seconds. All good after that. Drove the coach for about 20 miles (necessary weekly trip to dump our tanks).
Then I tackled the secondary by first making sure I could unscrew the handle of the little priming pump attached to the secondary filter base. Couldn’t do it with my gloved hand but got it turning with slight help from a pair of channel-locks. Unscrewed it and tried a test stroke to see what using this pump was like. Pretty stiff resistance and very awkward to reach in and use, but do-able.
Next, I made sure that I could loosen the secondary filter.
Then I removed the wrapping from the new filter and set it in a secure upright position where it would stay clean.
Spun off the old filter, dipped a finger and used fuel from it to lube the gasket on the new filter. Then spun it on. Tightened per instructions on the filter.
Finally, started stroking the pump. A stroke is only about 2 inches and there was minor resistance in both directions. Did 57 strokes before resistance seemed to max out. Screwed the pump handle back in and tightened by hand. This number of strokes may seem daunting but just takes a couple minutes. No big deal. It’s just that the pump faces away from you and you must reach in past the filter base and fuel lines to get at it.
I never heard a check valve click while pumping but did hear a quiet whining/sucking noise that was proportional to the pump resistance I felt. Sound stopped a few seconds after I paused pumping and resumed when I started pumping again.
Engine started right up, no unusual ‘check engine’ lights, no extra cranking, no problems. Big relief. Checked another box on coach ownership!
