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Jarvo2

240z Electric Fuel Pump Installation

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In an effort to make the 240z more reliable, I've decided to upgrade to an electric fuel pump and then retire the mechanical pump. By using quality parts and a smart plan, this will prevent vapor lock, keep the float bowls properly filled, and should allow for the car to start easier.

Parts List

  • Fuel Pump (low pressure, 4.5PSI max, 30GPH): Airtex E8016S (~$38)
  • Oil pressure switch: Airtex OS75 Safety Switch Oil Pressure (~$15)
  • Mechanical fuel pump block-off plate (~$25)
  • Brass "T" (1/8" FIP): Watts AC-704 (~$5)
  • Brass male-male (1/8"MIP 1/8"MIP): Watts AC-714 (~$2)
  • 30amp automotive relay: Dorman 84601 (~$5)
  • inertia switch (optional)
  • Wire, fuses, and miscellaneous connectors
  • Fuel Hose

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My first step was to plumb the engine block for an Oil Sensor Safety Switch. As you can see from the picture below, I inserted a "T" joint to allow me to keep the current oil pressure gauge (second picture) as well as the new safety switch.

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Next I needed to design a reliable and safe wiring scheme which would incorporate the factory wiring for a fuel pump but also allow for the safety switch and relay. In the diagram I drew below, the GRN wire and the BLK/WHT already exist in the wiring harnesses; the plug is just taped to another set of wires below the fuse box.

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The fuel wire harness is held with blue tape (see circle). The BLK/WHT wire is live with the ignition switch. The GRN wire goes back to the fuel pump (wired from the factory).

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There are two unused harnesses. Left is the Fuel Pump, right is the Fog Lights

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Here are two initial photos of the new electric fuel pump installed. I ended up using an existing bolt/nut for the mustache bar to mount the pump.

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I ended up putting it on the firewall inside the engine bay. Once I clean up the wires (taping & making them look 'factory') I will post some additional photos.

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FWIW my electic fuel pump conversion on my 72 did nothing to prevent vapour lock.

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I'm pleased to report that everything is working as designed (and no leaks!). I can not believe how quiet the fuel pump is!

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I would like to see how you manage wire from Oil pressure switch to the firewall too.

Thanks,

Tamo3

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FWIW my electic fuel pump conversion on my 72 did nothing to prevent vapour lock.

I'm in Florida, USA {pretty hot here all summer} - I've never had a vapor lock issue with any 70-72 240Z here. Maybe you didn't actually have a vapor lock? Perhaps some other restriction in the fuel lines? Are you running headers - with no heat shielding? Is your fuel return line clear? Carb's in good shape? Did you eliminate the mechanical pump when you installed the electric pump? Just curious.

Fuel lines pressurized to 3.5 psi - 4.5 psi should clear any vapor problems fairly quickly...

Did you ever get the problem solved?

Edited by Carl Beck
added more quesitons
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I can't say for sure that I've had vapor lock, but the engine (even with rebuilt carbs) has never run well. My carb's run much better now with the electric fuel pump. My guess is that my 40 year old mechanical pump was the issue, probably a bad diaphragm. I did remove the mechanical pump completely, along with a block-off plate. I do have a NOS mechanical pump that I've got on the shelf, but I like the idea of running an electric pump in this driver. More pictures of the wiring to come soon.

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Here are my latest photos of the relay and oil pressure gauge. I provided an initial wiring pic as well as one after I bundled the wires with electrical tape. Although this is new tape, it somewhat matches the 40+ year old tape that was used for the factory harness.

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I'll have to hook my FP pressure gauge up to see exactly what I'm getting. For those paying attention to this thread, I did locate pictures of the OEM fuel pump, hoses, and parts sheet (compliments of a seller on eBay). The interesting thing is that the Nissan wiring harness is just an inline fuse, nothing to do with an oil pressure switch nor inertia switch. At least the OEM harness is powered by the ignition.

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I did this conversion in 2002 and have been using a electric pump from a RX-7 non injected car. Have never had any issues with vapor lock or any problem for that matter. I eliminated the mechanical pump, they act like a heat sink, and block off the opening. I have since changed engines to a F-54 with a P-79 head with cam and headers. No heat shield other that factory and again no problems. I used a simple tee into the block much smaller than the one pictured , attached the pressure switch to the side opening and the sending unit on the other. Looking at the area you cannot even see any difference from stock. I simply ran a couple of wires fron the pressure switch , right to the green wire comming from the pump on the passenger side . Cut the wire and connectec my new wires in line. This power sorce is fuesed , factory, with a inline 20 amp fuse between my splice and the power sorce. I can see no need for a relay, The pressure switch I use closes when the oil pressure reaches 7 psi. then the pump is activated. If you ever run out of gas, simply use a modern fuze with two male spade connecters , un plug your wires and bridge them with the fuze . Turn the key and fill the float bowls. I have had to do this only once. Even after winter there is enough gas in the carbs to start the engine. But if not I use the fuze. This makes it a simple and clean uncomplicated modificaton. Just take your oil sending unit with you to your parts store , tell the counter guy what you want to do so you will be buying the correct threded parts. This is about a $10.00 conversion . The RX pump is quiet too. $15.00 at the local u-pull-it. they make 4 1/2 psi. I cecked wtin ztherapy when I did this and Steve told me the limit pressure is 5 psi.

Hope this is helpful. All the best. Gary

Edited by beandip
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I ended up bringing my oil pressure sensor to Menards (hardware store, similar to Home Depot) and then did some trial and error in the brass plumbing section. I believe it was 1/4". Don't forget you'll also need a male-male straight pipe to get the "T" into the block. Looking back, the oil pressure switch was a little bit of overkill, but I am aiming for safety and drive-ability. I've heard of some people pulling power from the yellow alternator wire to power a relay (avoid the need for the multi-function oil pressure switch).

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where did you mount the inertial switch and is needed ? I have never used one will cut power if you hit some railroad track hard ?

thanks for the write up going to follow your directions on my build .

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I decided not to install an inertia switch as I'm going to rely on the oil pressure gauge to cut the fuel pump off if the engine stops. From what I've heard, you can easily find a used one at a wrecking yard, or purchase one from RockAuto. It needs to be in a place that it can be reset, although I don't think speedbumps/railroad tracks would trigger it to flip unless you pull a Dukes of Hazzard jump.

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You can always put in an on/off switch in lieu of the inertia switch, which would then act as a hidden fuel cut off switch....good luck getting the car started with it turned off!!

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hi, im wondering how do u regulate your fuel?? bcus doesnt the fuel need to be regulated or it will overflow the carb?

please, give me a text for faster response. (209)-947-7595

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The airtex pump I used only produces 4-6 PSI which is fine for the SU's. If you get a higher pressure pump then you'll need to put a regulator in somewhere between the fuel filter and the hard fuel line in the engine bay. I haven't had any issues with my low-PSI pump.

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Will using the oil pressure switch cause the engine to crank a few more times (To build pressure) before it starts?  Or will the fuel in the fuel bowls take care of that?

 

 

I'm just curious as every car i've dealt with, as soon as you turn on the ignition you can hear the fuel pump run right away.   Look's like I have to do this conversion as my N47 head does not have a mechanical pump cutout.

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The switch I had bypassed the oil pressure when it got power from the starter.  Check out the schematic that I drew.  There is a switched power, Starer Power, and output on that switch.

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Ah, ok.  I didn't realize the oil pressure switch was a "three way" switch.  The diagram didn't make sense at first, but i've got it now.  Thanks for the write-up.

Do you know if all late model 240's had that unused wiring in the harness?

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