electric vs manual

[Ramses]

Hey,

I was doing some work underneath my car and I discovered an electrical wire coming from an electrical fuel pump. The wire is twisted around the wires for the reverse light, so it is not hooked up. Also when I was playing around with it I hooked it up and it works. It makes a thumping noise that you can hear outside the car, but not inside when it is running. I have put about 200 miles on since the refresh and was starting to do the bushings and bearings, it seemed to run quite well without the electrical fuel pump. I know that the electrical fuel pump was an aftermarket or dealer item for the '73, but why would they put it on while the manual one works perfectly fine? Should I reconnect it, or leave it disconnected? The rear wiring harness has a wire that looks like it goes to it, but if I connect it to the harness it gets no power, so the only choice to power it is to follow the drive chain and connect it to the secondary wire off the starter. It does not look good, but not that many people will be looking at my car from underneath the car.

Any Suggestions?

[Carl Beck]

Hi Chuck:

The electric fuel pump was installed on the early 73 240-Z's as part of Nissan's attempt to resolve starting and running problems, mostly caused by the manor in which they meet the 1973 Emissions Standards. Higher combustion chamber temps., the flat top carb.'s and changes to engine ignition timing. The Dealers installed various "Kits " of items in Stages.. depending on how bad the problems were. (it wasn't an option so much as an attempt to get the cars to start and run). The problems with the fuel system were percolation, vapor lock and vacuum break.

Past a certain time, Nissan starting including the electric fuel pumps at the factory on all 73's. In either case, Dealer Service Installation or Factory the existing wiring in the wiring harness was used to power the pump.

You found the wires back by the tank. In your 72 there are two wires with female spade connectors in the wire bundle that is to the right side of the dash/center console interface. You have to make a jumper wire with two male spade connectors to join the two female spade connectors together. That will send power to the pump.

In your 73 there should be two relays, bolted to a large relay bracket just above your feet on the right side kick panel. One relay powers the second relay that controls the power to the fuel pump.

See: http://zhome.com/Dropbox/73FuelPumpRelaySm.jpg

You can copy/download the image and blow it up

If someone has changed out the carb,'s on your 73 - to the earlier SU's and car runs fine with the mechanical fuel pump - I see no reason to hook up the electric fuel pump. If your car still has the original Flat Tops... then the electric fuel pump will help a lot with hot starting and running on warmer days.

In either case I would trace and remove the jumper wire someone else installed... you'll wind up with a short or floating ground you don't need...

Hope that helps...

Carl B.

Carl Beck

Clearwater, FL USA

http://ZHome.com

[Ramses]

Thanks Carl,

I was wondering what those two relays were. I removed them, because I thought they were redundant. They also were not on my wiring diagram. I appreciate it. I will check next summer to see if I need them. Otherwise I will remove the additional wire and use the wires supplied to the harness near the pump.

Chuck