Changed my fuel filter the other day and while down there I found this dangling by itself.

Comes from the wiring harness that's below the oil filter.

Does it need to be grounded or just mounted somewhere?

 

That needs to be grounded.

 

It needs to be mounted to the engine block. Often it is mounted at or near the clutch slave.

 

but what is it?

what problems might it currently be causing?
just bought this car and haven't driven it much, but it has some issues.

 

Capacitor for the oil pressure gauge.

 

Ah. Thanks guys

 

Throw it away.

 

If you just bought it I would be worried about injectors leaking and that drainback system they tee-d into the fuel lines.

Like this. http://www.mazdatrix.com/c-bleed.htm

 

Huh... I thought that setup looked not-factory.

I do have a bad case of flooding also, and I think I just burnt out my starter as a result. It just whirs now without catching.

So, I guess this means I've got a bad injector somewhere and this setup was someones band-aid?

This is my first rotary and I don't know how it's supposed to look.

Oh yea, and just for fun this is the CAI the PO installed, with a nice big gap that they used packing tape to fill...

 

It is advised to send the injectors off to be cleaned and flow tested(less than $100). Once thats done remove that bandaid fix and diagnose any other problems with the car. Is it flooding from hot starts cold starts or both?

If you're going to have the manifold off to get to the injectors its the best and easiest time to replace the fuel pulsation dampener and coolant sensor(which can cause flooding when bad). Cleaning up the ground under or around the manifold should be done. Hell odds are the vac lines are shot also. Really should should just plan to pull it and have the car down for a week if at all possible, there are many things you can fix in one foul swoop right there. You may not NEED to do it, but it'll really help potential future problems.