That little silver thing has a little gasket inside with threads. Doesn't seem to fit anything.

 

I'd say that looks like a temporary use tool. The pins on the male end are used to remove the schraeder valve from the housing. Once this is done fuel will flow out of the schraeder housing, to be able to apply pressure to the gauge. Otherwise, the valve seals the fuel in the fuel rail, and the gauge won't read anything.

I am not sure what the female side with the gasket would be used for. It looks too small to screw onto the schraeder port to cap it, when you want to take the gauge off.

 

I agree, it's a cheap valve core tool. That can double as a tire valve cap.

 

So do you think I can just install it without using that little valve?

 

You need to remove the valve core so the fuel/pressure reaches the gauge.

1. Remove the cap (if present) on the fuel rail test port, on the passenger side rear end of the fuel rail.
2. Use the silver tool to remove the valve core from the port.
3. Put the core (the small part removed) and the tool into safe storage.
4. Attach the gauge to the 90* adapter fitting.
5. Attach the 90* adapter fitting to the fuel rail test port.
6. Turn on the key, but do not start the engine yet. Check for leaks and for the gauge to show pressure.

 

Hmm I'll have to take a look at it once I get home. But if I recall correctly when I unscrewed the old fuel gauge, it just left a threaded hole straight into the rail. You say there is suppose to be a valve core in that hole?

 

You didn't mention you already had a fuel gauge on there.

Yes, there is normally suppose to be a valve core in the fitting. That is what seals the hole, and prevents fuel from leaking or shooting out of the test port.

The valve core needs to be removed to use a fuel gauge. Since you are using a fuel gauge, it is supposed to be "missing"/removed.