So I know I have a mech fuel pump on my 260z

but few days after I picked it up and driving the hell out of it!

I started to hear this sound that kinda like a slow air pump for a fish tank!

and its in the location of the electric fuel pump but looks like nothing stock and is a small box thats wired in! and has fuel lines running to it!

Its now making a kinda odd knocking sound as if its dieing!

but i'm not sure if I even need it!

Looks like a low pressure Facet brand aftermarket pump. I have one sitting in my tool chest since about 1980.

Dennis

hmm does the car need a pump at all or does the mech do a job as it stands?

The 260Z had both the mechanical and an electrical fuel pump. Supposedly the electric pump was to prevent vapor lock.

Personally, if the car runs well I would leave it alone. If the pump is giving you trouble there are other types available. It does have to be a low pressure pump for the carb based engines.

well the knocking sound it makes kinda sucks at idle!

I have a Holley electric pump, and it makes a whirring sound that can be heard at idle. There are some threads here about various pump styles, so if you want to replace it try searching. You could try removing it and seeing if the car still runs correctly.

If you replace it, be sure to get a pump that is made for carbureted engines. The fuel injected ones have too much pressure, and will cause things to fail...

Looks like someone replaced the original electric fuel pump with that smaller one.