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'73 240Z Electric Fuel Pump & Wiring Concerns

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Old Nov 11, 2014 | 02:11 PM
  #1  
PCressey's Avatar
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'73 240Z Electric Fuel Pump & Wiring Concerns

I was in the process of replacing the stock electric fuel pump and removing the mechanical fuel pump, in order to install a Holley electric fuel pump.

When I checked the wiring to the stock fuel pump, the wire was not hot... no power. I pulled out the center console and checked the wires, and the wire with the fuel pump fuse is hot. I traced that to some resistor box (I think?) and none of the wire were hot there.

I have am attaching photos of where the fuel pump fuse wire goes into the resistor box... when I pulled the wiring from the resistor box and checked the wire, it was not hot.

1. What are these two boxes?
2. Why would the wire not be hot?
3. Is this bracket shown in the second photo stock? This is an AC car.

Any help is appreciated... I would rather use the stock wiring, than running my own wire.

Thank you!
Attached Thumbnails '73 240Z Electric Fuel Pump & Wiring Concerns-20141111_133741.jpg   '73 240Z Electric Fuel Pump & Wiring Concerns-20141111_133803.jpg   '73 240Z Electric Fuel Pump & Wiring Concerns-20141111_133827.jpg  
Old Nov 11, 2014 | 07:57 PM
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Figured out the problem... one of those boxes appears to be a relay. I opened it up and pushed it down with the ignition on and the fuel pump ran.
Attached Thumbnails '73 240Z Electric Fuel Pump & Wiring Concerns-20141111_195120.jpg  
Old Nov 12, 2014 | 03:35 AM
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More info available at http://xenons30.com/files/1973%20240...ifications.pdf
Old Nov 12, 2014 | 08:18 AM
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Thanks, Steve. I found that document a little later, but didn't have time to update.

It looks like they removed the starter solenoid connection from the piggy backed harness/relay, so the fuel pump never ran while cranking the engine.

Anyway, I removed all the safety piggy back equipment (relay) and wiring harness to the engine bay... if I crash the fuel still pumps causing me to die, it is on me.
Old Nov 12, 2014 | 09:01 AM
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http://www.amazon.com/s/ref=nb_sb_ss...ch%2Caps%2C484
Old Nov 12, 2014 | 09:12 AM
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Even better: fuel pump inertia switch | eBay
Old Nov 12, 2014 | 02:53 PM
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Steve,

Great... I didn't know those existed. Got one off Summit http://www.summitracing.com/parts/sum-890145
Old Nov 13, 2014 | 03:55 AM
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You might have a challenge with the connector. Some of the ones on ebay are used and have the connector from the wiring harness attached. Wired in properly, it gives a better margin of safety than the Nissan design.
Old Nov 15, 2014 | 01:19 PM
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Originally Posted by PCressey
if I crash the fuel still pumps causing me to die, it is on me.
I suspect you're joking but please don't let that car stay in an unsafe condition. It's not just you who might die. Passengers, drivers of other cars, firefighters and other heroes who may attempt to save you and so on.

Impact cut off switches are not hard to find or install.

Edit: Should have read the last couple of posts ... all is well!
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