Electric Fuel Pump Install

[Randalla]

I'd been having fuel delivery issues on my 72 240Z, even after installing a new (brand X) fuel pump. It worked for a short time and then failed, nearly leaving me stranded. I have been using an original Kyosho mechanical pump for years but it was not pumping with consistent pressure. I decide it was time to swap in an electric pump, but left the mechanical pump in place for stock appearance. As I'm sure many of you know, there is wiring at the tank for the pump that is wrapped (green, and black wires). Apparently, the 1972 harness anticipated the addition of an electric fuel pump in 1973 models. Mounting and wiring the fuel pump in was pretty straight forward. Then I needed to determine how the pump would get triggered by the ignition switch. I learned online there were also two unused wires (green, and black with white tracer) behind the radio that are there to complete the install. Ron Q, thank you for all your help diagnosing how to properly wire the car forward of the pump. Turns out we simply needed to connect the two wires together using a female plastic connector and an inline 20 amp fuse. All good now so far.

[L320-Dale]

Good info Randy. I wonder if my 70 has the same wiring?

[Duffman]

Great solution, Randy, glad Ron is good for something!

Wonder why your mechanical pump is no longer working as well? If it is not a bad pump, what could it be? My mechanical has been working fine and pressure consistently pumping out 3.5 psi. Strange ...

[cgsheen]

Good info Randy. I wonder if my 70 has the same wiring?

Yes it does. I recommend that you also install an inertia switch to cut power to the pump in case of a collision.

[L320-Dale]

Thanks Chuck.

[Randalla]

Yes Chuck, an inertia switch is definitely in my future. Steve, I think the rubber diaphragm on the pumps go bad and start leaking air. Mine worked sporadically but I never knew when it might leave me stranded. Car now starts better and seems to run more evenly. The only downside is the noise. I just bought a cheap $30 pump to make sure that was the problem but will likely upgrade with a quieter one. I did isolate the mount from the chassis with some rubber bushings but the pump itself is still fairly noisy. Car ran great all day yesterday in over 60-80 miles of driving.

[Duffman]

Yeah, Randy, I understand how a mechanical pump can go bad, am surprised mine hasn't gone bad due to not driving the car much. Guess it is hit and miss on quality of the mech pumps!

I heard the Mazda RX7 electric fuel pump is supposed to be pretty quiet.

[Randalla]

Thinking I'll wire in the inertia switch under the dash so I can also use it as an anti-theft device when switched off. I believe that would keep the car from being driven any further than the gas in the fuel bowls would allow a thief to drive it.