240Z in tank fuel pump conversion

Why an in tank fuel pump?

This in tank fuel pump conversion is part of my Whitleytune ITB EFI swap to my Datsun 240Z.  I had previously had a Holley Red external fuel pump that supplied fuel when the engine was carburetted.  This set up was noisey, smelly and exposed to the elements.  The new setup had to be better than this and the only set up better was a fuel pump in the tank.  

The inspiration came from Mighty Car Mods RB26 swap into a 240Z which used an Aeromotive kit in the shallow part of the tank under the spare wheel well.  This kit appeared to be a quality unit but for my fuel tank would not work.  The fuel tank in MCM’s 240Z was different to my own.  This is likely because the car was an import and had more depth because of a hump in the top of the tank under the spare wheel well..

MCM’s conversion only required cutting a hole into the tank with no other welding.  And that was my goal, a no weld a conversion. Being the engineer I am I started looking for alternatives.  

If you’d prefer to watch a video of my 240Z in tank fuel pump installation, skip to the end.  I have embedded the video from my Youtube channehe

Enter the Tanks Inc PA system

It only took a small amount of research before I came across Tanks Inc.  A number of Z car owners had used the PA kits.  However in all instances I found the kit was installed in the tall end of the tank with modifications to the tank itself.  I still looked at the kit and researched the installation method.  The typical installation orientates the pump vertically.  

Knowing a little about Walbro pumps, I knew these pumps are suitable for a horizontal arrangement.  After a bit of brain storming (and finding a suitable fuel filter!) I developed a method to install the pump horizontally.

DISCLAIMER: I have only performed this installation on a 1971 240Z S30 with a non GVRS fuel tank.  I suspect the is likely to be suitable to other fuel tanks however if you perform any modification contained on this webpage you do so voluntarily and at your own risk.

Components

The key parts required for this are the Tanks Inc kit and a horizontal orientation fuel strainer.  I used the PA-4 (Walbro 255lph rated up to 630hp) unit for my EFI build however Tanks Inc offer a number of low and high pressure pumps to suit your engine aspiration and power requirements.

The two parts used in this conversion are:

  1. Tanks Inc PA-4 in tank kit (eBay link)
  2.  Horizontal 22mm fuel pump strainer (eBay link)
  3. Appropriate fuel safe sealant (eg. Threebond liquid gasket)

Installation steps

Working with fuel tanks can be hazardous.  Residual fuel and fuel vapour stays in a tank for a long period of time.  Be sure to clean the inside of the tank and give time for the vapours to dissipate prior to working on the tank.

1. Locate and cut access hole

Most S30 fuel tanks have baffle plates around the pick up in the middle of the tank.  Locate these through the filler neck when planning out the access hole.  Once located use a 114mm (4.5″) hole saw to cut the access hole. Take your time with the cut and use cutting fluid if needed.

2. Drill the mounting holes

Turn the mounting plate upside down and use as a template to make out the mounting holes.  Mark and drill a couple of holes around the perimeter.  Use these holes to dummy fit the inverted mounting plate and use as a jig for the remaining holes. 

Prepare the cut surface ready to mate with the mounting ring and mounting plate.  Some massaging of the tank skin around the hole may be required to ensure the surface is flat for the full perimeter. 

3. Construct the tray

This step is where we deviate from the Tanks Inc installation and requires some extra skills.  First the tray needs to be test fitted to verify how it will feed through the hole.  Because we are working the shallow part of the tank it is likely that a small bit of material will need to be removed from the walls of the tray (I had to for my 240Z tank).  This is to allow the tray to be slipped into the tank at an acute angle through the access hole.

Next measure and cut down the standoff on the mounting plate.  The slotted holes in the standoff may not align with the factory cut holes.  In this case drill a new hole.  Bolt the tray together and test fit to ensure the assembly can be fitted properly through the access hole.

4. Assemble the fuel pump

Take the horizontal fuel strainer and fit this to the pump.  Install the bosses in the mounting plate considering the orientation of the fuel supply and return lines.  I orientated my bosses towards the font.  Note the bosses have tapered threads so do not overtighten.  I also recommend using a sealant like Loctite xxx.

Test fit and cut the fuel lines and the white return line.  You may find when you test fit the pump that additional support might be required to hold the pump in the correct location.  I cut a narrow strip from the mounting plate standoff excess and checked out the walls of the tray to allow fitment over the pump.

Put everything together.  I recommend using a cup of hot water to soften the hose ends prior to fitment.  When done feed the pump wires through the grommets and tighten these.

5. Install the assembly in the fuel tank

This is the last and the trickiest step.  The mounting ring can be tack welded to the tank to hold in location.  I did not do this and in hindsight would have made things much much easier.  Make sure the mounting ring is in approximately the correct location prior to fitting the gasket and assembly.

I recommend using a good quality fuel rated sealant on both sides of the gasket.  I used Threebond liquid gasket maker.  Slip the gasket over the tray and under the mounting plate.  Install the assembly while holding the mounting ring to the underside of the fuel tank if not tack welded.  Use one of the longer screws supplied through any hole, and feed it through from the mounting plate to the mounting ring and start the thread by hand.  This will give you a ‘joystick’ to assist with orientating mounting ring.

Seat the fuel pump assembly in the fuel tank.  Using the first long screw, progressively start the threads for all the other screws.  An awl might be required to align holes and the gasket.  Depending on your sealant you may need to act quickly.  Once all the screws are in, tighten the screws working on opposing sides (like installing a wheel to a hub) until all screws are tightened.  Install the remaining hardware once the sealant has properly cured.

Final fitting comments

How you orientate the hose hardware will depend on your build.  I also found that I needed to pack the spacers on the shallow section of the tank with 5mm thick neoprene held in place with a daub of silicon.  This gave some additional clearance between the hoses and hose hardware and the bottom of the spare wheel well.  Wiring will also depend on your build requirements.

While I had my tank out, I took the opportunity to replace the vent hoses particularly the top hose with the 180 degree return.  See that guide here.

Thats my no weld 240Z in tank fuel pump conversion!  Check out my Youtube channel, instagram page and facebook page.  If you want personal assistance, send me a message on Instagram, Facebook or email my at info@builtonpurpose.co