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
  

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.

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.

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).

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

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.

Thanks for the detail posting. Where are you going to mount relay?

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.

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

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

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

Thanks,

Tamo3

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 January 25, 201312 yr by Carl Beck
added more quesitons

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.

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.

Better shot of the electric fuel pump as well as the block-off plate on the head.

When i tried that Airtex pump, I was only able to get about 2.25 psi out of it. What kind of pressure are you getting at the carbs?

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.