Well I had the same problem today. The presoak did not work and the pressure built up on the outgoing side of the check valve so the check valve could not open. This time I called Greg for a little help. I adjusted the air regulators (there are 2 air regulators one for the sides and one for the top). I let the unit pump presoak for about 15 minutes and ran the gantry back and forth down the track to try and replicate the problem. Greg believes that there is a kink in the presoak hose somewhere in the system.
The Procom pump is running at 75 psi and the pressure at the gantry is 50 psi, the air is set at 35 psi.
My Jim Coleman Water Wizard stopped delivering presoak! (I only run one presoak and the system is closed to high pressure but does use air.) The problem I am having is I am getting pressure buildup on the outward side of the check valve which does not allow the valve to open. What does not make any sense is how the pressure builds up. I ran the presoak function for about 10 minutes and it worked fine. Ran a couple cars through still no problem. It just quits working whenever it feels like it!
I brought the Torero Inflatable over to the Express wash today and set it up. I decided to make a video to show it off. You should check them out at: http://www.toreroinflatables.com/ It will be interesting to see if the sky dancer helps increase sales. Something needs to after all the rain.