Packard Forum Index » Post-War (1946-54)

When I got my '50 Custom it came with a flow through electric fuel pump. The car also had reversed polarity with a negative ground. When I fixed the polarity the fuel pump stopped working, so I switched the wires around on the pump and it worked again. The pump was wired directly to the coil so of course it ran constantly when the ignition was on but I only wanted to use it to prime the carburetor. So I re-wired the pump to the ignition switch and added a marine switch that has 3 positions; 'Off' in the center, 'Finger Pressure On' to the left and 'Stays On' to the right. This way I can hold the switch to the left for some seconds to prime the carburetor or flip it to the right for emergency use. The mechanical fuel pump works just fine and I rarely use the electric pump even to prime. It's doubtful I would have added an electric fuel pump if the car hadn't come with one.

If you're going to have an electric pump, that setup and plan for use sounds pretty ideal. I envy your 1950 Custom 8, I had one years ago that I bought while in college for $85 from Paviol's Garage (Studebaker/Packard dealer) in Carlisle PA. The 22nd/23rd series Custom 8s are what I consider to be the last of the real premium luxury Packards.

Here is another set up, combining several approaches mentioned, with both an electric and mechanical pump. This is the set up that is on my 34. The electric pump is installed with a bypass line and check valve and wired to a momentary on/off switch. The mechanical pump is installed in a standard fashion. Immediately before the carb a T is installed. On the descending portion of the T, a restriction fitting is placed, and then a fuel line that returns to the tank. The restriction fitting is sized so that +80% (approx) of the fuel pressure is delivered to the carb, the remaining pressure drives fuel back to the tank.

With the set up, the mechanical pump runs faster, but shallower. Fuel is constantly being re-circulated. The electric pump is only needed for priming if the car has been sitting a while, or to briefly add a little pressure if a vapor lock is being experienced.

The benefits:

1) The recirculation of fuel keeps the fuel system cooler and greatly diminishes the potential for vapor lock.

2) If the mechanical pump begins to fail, the driver will notice before the pump completely fails.

3) If the engine stops, the pump stops.

4) If the engine begins to starve for fuel do to a vapor lock, a very brief pulse from the electric pump will clear the lock.

The drawbacks:

1) The mechanical pump diaphragm may wear more quickly. I'm not sure of this yet. I've driven the car approx. 2000 miles with the set up, and it is still good.

This system worked great on my trek from Minnesota to Warren, OH (approx. 925 miles) last summer. We were regularly driving all day in +85 degree weather. We would experience vapor lock (engine stumbling) when the fuel tank was nearing empty. A brief pulse with the electric pump would clear it up, and a re-fuel would solve the problem for another couple of hundred miles.

Tom

Attach file:

---

  (41.21 KB)


  (13.96 KB)

Sounds interesting for lots of cars. How was the restriction made and then sized to determine the amount? Trial & error or some real calculation?

Quote:

Trial and error after calculation. I don't remember the sizes, but we started with a restriction that was 20% of the plane area of the fuel line.

Hey Tom - what's that vacuum advance unit doing on the distributor?

And you fuel pump hookup is the elegant and probably the very best way to do it.

Because then you are not circulating cooler fuel from the tank.

Thanks Kev.

Quote:

Dave,

I am embarrassed to say that I don't know what that vacuum advance is doing there. The car got a Delco replacement distributor sometime in the 70s, and that is probably when the vacuum advance was added. I don't know why it was added to the original style replacement northeast unit, however. I will enquire with Tom.

And thanks for the comments on the fuel set up. Tom R. has used that particular arrangement on a number of the cars he has done.

Tom

34roadsta. What did u use for a check valve at the electric pump bypass???