Restarting an old fuel injection system

Hi Folks,
I've worked my way down my list and my '85 ZN1300 is up next. I think that's the correct designation for a fuel injected 1985 Kawasaki Voyager 1300. I'm sorry to say I didn't treat this fuel tank very well these few years. The tank was full when I stored it but it didn't fare well. Fortunately I'd disconnected the tank from the injection system so other than drying out, it's at least not contaminated with old fuel.
That brings me to the relief valve in the bottom of the tank. it's Kawasaki part number 16130-1002. Is it really a valve or is it just a port that the pressure regulator vents through?
TIA
Bill

Reading through the Digital Fuel Injection System in the ZN1300 Service Manual, on page 3-24 it suggests that the fitting in  the tank is a check valve.

 

Thanks Kawboy,
Perhaps the relief valve is just a port to vent excessive pressure from the injection system, as determined by the pressure regulator, AND it's a check valve to prevent fuel from draining back from the tank should something go wrong with the injection system during down times. I've tried blowing air through it but it seems totally blocked.
I could just drill it out and add a valve, as a short term fix.
When I last looked at this project I added a DG six into one exhaust system and had the pressure regulator modified to be adjustable. I have ridden this bike once or twice. As I remember Ma Kaw fitted a seven disk clutch instead of the nine disk clutch that was standard on the KZ 1300 and I remember this one slipping readily. I already have a couple of spare clutches. Think I've even got the deeper clutch cover.
Bill

I'd soak it in Lacquer Thinner overnight and then try moving  the valve internals

On my GPZ1100 it is a simple inlet to the fuel pressure regulator surplus tank.

When I disconnect the hose, fuel comes out of the tank inlet fitting.

I soaked the valve in Carb cleaning solution over night after which the valve started cycling. I have yet to fill the tank but I'm thinkin that it'll stop the back flow if the hose is disconnected.
I'm pretty sure start up is coming soon. Still need a fuel pressure gauge, it's ordered.
Bill