The following applies to modern systems with a solenoid in the intake manifold of the feed pump module that flush through the strainer (2014 and later Newport series):
Flush issues, specifically with no freshwater flow at all, typically relate to the flush solenoid, freshwater house pump, or the circuit board not supplying the solenoid 12V. Before proceeding further, ensure the small blue handle to the left of the charcoal filter is fully open to allow freshwater through.
We call the black rectangle sticking out the side of the feed pump module with all the fittings the “Intake Manifold”. Photos are below. If you find the system is not flushing when supposed to be, a good way to attack this is to chop it up into sections and see where the flow stops.
First, to test flow from the house pump you can disconnect the hose between the charcoal filter and “From Flush Module” on the intake manifold. Be prepared for water to stream out! To minimize the mess, open the pressure relief valve on the Clark Pump at least 1/2 turn so the system depressurizes. That will confirm your house pump is moving freshwater when asked to.
After that, reconnect and you can disconnect the hose between the intake manifold “To Strainer” fitting and the tube fitting elbow on top of the strainer module. There should be no flow. Press Flush on the control panel. If water does not flow when you press flush, the issue likely lies with the solenoid (either not receiving 12V during a flush, malfunctioning, or clogged with debris). If you listen closely with your ear to the intake manifold, you should be able to hear an audible click of the solenoid snapping open when you press flush. If water is flowing, there is no issue with the solenoid and the problem could be a physical obstruction somewhere else in the flush path. If still no flow but solenoid is receiving power, disassembly of the solenoid is advised to ensure it is free of debris and can move freely. Below are further images of the solenoid disassembly in case you need to see how it can be removed.
If solenoid is not snapping open and is clear of debris, adequate power should be confirmed, either at the solenoid wires if accessible or back at the Spectra Connect board via the VALV2 & GND terminals (pictured below). The solenoid will only receive power for the duration of the flush cycle. To review a wiring diagram, please visit: Wiring Diagrams