RMW2.5G28.brass head . NO pressure out put .. Eng off and no Hi side hose on it water will run through it ,start Eng water will Stop going through after 1 Min or so thermal valve will go off /on -off/on ..
I see No leaks , If I back off way off on the adj on the unloader water will start to go through but soon as you increase adjustment water will stop going through .. Thinking its the unloader frozen ,removed- all is nice and clean and free moving and No rust on spring ,O ring have No marks or cuts all looks good .
Open for a Fix ??

You have a Good Point but in my case that was not the issues .. I found the Injector ( #41 in the parts breakdown) came lose .Now to fig if any internal damage was done to head built in seat for shutter #38

It’s very common for this to happen on the RMW pumps. The jet valve behind the injector gets stuck and stops the flow and when this happens it often times damages the check valves.
Try taking it apart and cleaning or get a new pump

Please be aware that this RMW2.5G28-EZ-SX pump from Annovi Reverberi is rotated 180 degrees, for mounting under your pressure washer Please see your units repair manual to determine if this is the correct mounting for your machine.

The RMW2.5G28-EZ-SX pump from Annovi Reverberi has the the following specifications:\

The unit is a Vertical Mount with Gas Flange 3-7 HP
Max. Volume on this pump is 2.5 GPM
Max. Discharge Pressure of this unit is 2,800 PSI
Max. Pump Speed on the RMW SX is 3,400 RPM
Shaft Diameter for mounting measures 7/8” Hollow
Built In unloader and chemical injector come standard on this pump
Built In easy start valve is also standard on this unit.
Maximum Horsepower Requirements to work this pump is 6.5 GHP
Inlet Port on the unit measures 3/4″ FGH (garden hose)
Outlet Port has a measurement of 22mm (Twist Connect)
Brass manifold for long life.
Stainless steel plungers built to make this pump last.
Pump comes filled with oil for quick step up and use.

Thank you so much, buddy, I am going for this product after reading your post I am ready to purchase it.