Shureflo 4008 Pump Intermittent Cycle Fix
I replaced my pump with a new one from Camping World (yes, I paid the big bucks for it), and from day one it would cycle every 10-20 minutes. I thought I had a leak in the plumbing and checked everywhere - several times - and never saw a drip.
A couple days ago I had a lightbulb moment, and realized that if the check valve on the fresh water inlet leaked, the pump would cycle. So... I checked it, saw some water and figured that was the problem. While I was at it I pushed the check valve piston inward and water blasted out. But it didn't quit when I let go. I ended up ruining the check valve- water pressure pushing outward pushed the O ring out of position, and I couldn't get it back in place.
After buying a new plumbing fitting and with a half-hour of work, I got the city fill line plugged up, so I could use my pump again.
I did a final test of the pump/water system. I pressurized the system and then shut off the intake valve going to the tank. The pump never cycled during the next hour, and the system remained pressurized. That verified that my plumbing is good, and there's leakback through the pump.
I called Shureflo customer service today, explained my problem, and got the fix. I will need to adjust a screw (5/64 allen) on the pressure switch. Clockwise, 1/4 turn at a time, and no more than 1 full turn. Haven't done it yet, but will when I feel up to removing the pump in order to access the screw. Hope it works, but at least I know that I don't have water dripping into a hidden spot in my trailer.
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