Adding a Primer Pump

If you are like me, your busy schedule may only let you enjoy your "Classic" once or twice a month.  Since modern gasoline evaporates so much faster than the fuel our cars originally ran on, starting them usually involves lots of cranking to refill the carburetor/s before the engine finally catches and begins running.

I read in the Porsche 356 Registry where members have added electric fuel pumps to facilitate starting cars that aren't run frequently.  That seemed like a good idea.  It involves inserting an electric pump into the existing fuel circuit.  I did a little research and decided this was something I wanted to do.  Before I begin, I'd like to mention an alternative that's just as effective at a fraction of the cost.  That involves adding a bulb type fuel primer that's typically used with boats.  The main drawback to this option is, it is only good for priming. Should the main mechanical pump fail, the bulb type primer won't get you home, however this option may be all you need.

I used Google and Ebay to see what products were available and determine the best price.  I found a pump that I liked with a low (3-5 psi) output.  Carburetors don't work well with excessive fuel pressure.  Fuel pressure regulators are available but not necessary for priming only.  If the car is being set up to run continuously on the electric pump, then I would recommend a fuel pressure regulator.  The pump I chose is made by Airtex.  Airtex makes a lot of the OEM fuel pumps for our modern cars.  Checking further, I discovered Advance Auto Parts could get this one for me overnight at no extra charge!

In addition to the pump, the following items were also needed:

Hook-up wire
Miscellaneous crimp connectors
In-Line Fuse (my pump is working fine with a 5 watt fuse)
In-Line Fuel filter (optional, my pump came with one)
Fresh Fuel Hose and clamps (This is a good opportunity to replace any old fuel lines.)
Mounting hardware as needed 
Switch to activate the pump. (Mine is a "momentary" switch from Radio Shack.  You may want to consider a switch with three positions, momentary on - off - on.  This would provide the option for continuous running, if desired)

Once you have all the pieces, it's time to find a safe spot to locate the pump.  I attached mine to a cross member directly under the gas tank.  There was even a hole there for a bolt!  Before diving under the car with pump in hand, it's a good idea to do as much assembly work at your workbench so you aren't doing all that under the car.  I soldered on a ring terminal for the ground and a covered spade connector for the power.  I sized the ring terminal to fit the mounting bolt so I could ground the pump with that bolt. Don't forget to clean the chassis surface and use a star washer to insure a trouble-free ground.  Optional filter plus fuel hoses and clamps can go on at this time too.  Now, it's ready for installation.  Go back under the car with the pump and mount it securely.    Next, you can connect the fuel lines.  My car was easy since it has a fuel shutoff.  You may want to run the tank dry or otherwise stop fuel from going everywhere.  Don't think you can quickly swap hoses around.  That never works. Work safe and always take the proper precautions.


Pump with hoses and wiring ready for installation


Time to work on the electrics so disconnect the battery ground cable.  Again, it's far easier to wire up the switch on the work bench instead of under the dash.  Find a good spot to mount the switch.  You don't need to drill a hole in the dash.  (That's bound to be points off!).  Take your time and find the right place.  After you decide where to mount the switch, you will be able to cut your wires to length.  You may want to get the power from the ignition switch or the fuse panel.  This will vary with each car.  The power should be controlled by the ignition switch.  With the key off, there should be no power to the fuel pump switch.  Add an in-line fuse for good measure.  Fuse the "Power-In" side rather than the "Power-Out" side going to the pump.  Next, run the power wire to the fuel pump.  This may require drilling a hole through the floor or firewall.  If so, use a grommet to protect the wire.  Once through the grommet, you can add a crimp connector and connect it to the fuel pump.

Push-button switch with in-line fuse and proper connector ready to install


Add fuel, if necessary, and check for leaks.  Reconnect your battery and give it a try.  With the lines empty, the pump will sound louder, at first, but in a few seconds it will be noticebly quieter.  That means the lines are now primed and the car is ready to start.  "Pat-pat" on the gas pedal and crank the starter.  Wow!  Your car is running on the first crank!  With this addition, your starter should last years longer.

If you have any questions, call me, email me, or corner me at the next meeting.

John Bennett