Electric fuel pump wiring early 260z

[Kurbycar32]

My car came to me with an electric fuel pump mounted just forward of the shock tower on the passenger side of the car. The wiring for the power went out the front of the car and followed the main wire harness around and connected near the coil, ground was connected to the base if the pump. When putting everything back together I found an extra fuel pump that came with my other z. That pump has a two wire connector hanging off of it as well as a ground wire connected to it's mounting base. Looking around I found a perfect mate to connect this "new" pump with solid yellow wires in exactly the area I would expect. I tested this plug for power though and found it was not hot regardless of key position. I was unable to find any info in the wiring schematics either. Does anyone know what this connector is for?

[Zed Head]

Looks like Nissan depended on the mechanical to start the engine.  The engine has to be running to get power there.  Looks like the correct plug though.

 

 

[Captain Obvious]

The fuel pump uses the same style of connector, but the one you found in the engine compartment is most certainly NOT for the fuel pump. On the 260, the electric fuel pump is mounted on a bracket back by the tank.

 

I don't have a 260 anymore to double check, but I believe the connector you found in the engine bay is for the air conditioning system. High pressure cut-out switch maybe? Mounted on the receiver/drier?

[Mark Maras]

Odd, I checked my 260, Sept 73 build date. If the connector, under the hood, comes out of the harness below the ID tag, mine has two yellow wires & is disconnected. The only three wire disconnected connectors are farther back & are not yellow FWIW.

[takayuki]

if my memory serves correct, that could be part of the starter interlock system..... but I could be wrong.

[Kurbycar32]

The fuel pump uses the same style of connector, but the one you found in the engine compartment is most certainly NOT for the fuel pump. On the 260, the electric fuel pump is mounted on a bracket back by the tank.

 

There is in fact an electric fuel pump by the fuel tank, but both of my 260's also have a second fuel pump up in the engine compartment.  On the car in question both electric fuel pumps were active and i only recently bypassed the one in the rear of the car.

 

Zed, i think you nailed it.  In my haynes manual it spells out the operation clearly.  The motor must be running at 400rpm or higher to engage the electric fuel pump.

 

My goal was to not introduce new variables when swapping the motor so I think i'll hook up the existing (known working) fuel pump with the wire all the way across the car, get it running, then replace both pumps with one good one in the back of the car.

[Captain Obvious]

I should have been more specific. I should have said... If the car hasn't been modified by a previous owner, then the electric fuel pump is mounted on a bracket back by the tank. Now, of course, if a previous owner mounted a second electric fuel pump up in the engine compartment and wired it in somehow, then there's no telling what electrical modifications he preformed to make that possible.

 

As for the mystery connector in question, take a look at the upper left hand corner of the 260 wiring diagram. There's a connector with yellow wires that says "To Pressure Sw." And take a look at pages AC-5 AC-12 and AC-13 of the 260 FSM. They talk about the high pressure cut-off switch there.

 

No telling if that's what that connector is for NOW, but I think it was ORIGINALLY for the AC system.