I have not put the new selenoid block on yet.Ahhh this all sounds so familiar (https://www.carwashforum.com/threads/chasing-gremlins-need-your-thoughts-please.20837/#post-170026)
Here are some quick thoughts and if you read the thread i linked you may find some of the same issues. Sadly my presoak is chem only however i was having a "dead heading" issue on the product side. it would work then just stop. few questions (sorry if you already answered)
When the product stops is the product pump still pumping?
have you pulled the product line from the sel when it stops flowing? making sure product is coming out of the sel.
your new sel block did you replace the product side or the air side.
have you checked that your getting signal to both air and prod sels when called? and when it stops working.
Long story short what i would do is for sure swap your air sel block for your new one (or a new one the rust can be an issue) and i can see the corrosion on the wiring connection points very Cleary. this can cause intermittent connection issues in the sel's and also short out your jumped common. (this was my issue) the wiring was broken inside itself from corrosion and causing the common to short it self causing the sel so stick open/closed, so the pump would run however the sel wasn't open. or was open jusstttttt enough to let some fluid pass through to keep the pump running after it was shut off.
also test your wires, if not just replacing the connections. look for continuity issues to rule out that. start with a new sel bank and see if that helps.
Partly because I need a few more pieces and partly becuase I am terrified of the wiring.
I am pretty sure it is the seleonoid Block. I know there is air to it as I took it apart and tested today.
Thank you for your help.
