Packard Forum Index » Pre-War (1899-1942)

After 2 vapor locks in Portland, Oregon, and having to crank and pump, or pour gas in the carb to get started after a few days sitting, I decided to install an electric fuel pump on the Duchess, 1940 160, to use on an intermittent basis.

Thanks to earlier threads that directed me to PAC's Technical Tips on the subject, I decided to follow the attached diagram for all the reasons covered in these technical articles and to keep the authentic look up top, with a couple of exceptions.

To find the parts needed in addition to the pump itself, an Airtex from Sacramento Vintage Ford, I called first and left work early Friday to collect the things I needed to install this weekend from places that are generally not open after 5pm and closed weekends. I'm talking about truck oil system and diesel fuel injection places. After making it to three places, I got a gauge and needle valve to control the pressure (you get a dumbfounded look when you ask for a pressure valve), some connecting pieces, pipe, clamps, and a fuel filter.

The check valves were large, so I added a fuel filter to serve that purpose. The point of highest pressure is between the 6v pump and the needle valve, so I used a brass connection there. Hose for the rest. With all the clamps I could have installed fuel injection.

So now comes the wiring. The tan wire goes to ground on a 1940 Packard with positive ground. I grounded it to the pump bracket which is attached to the frame with a bolt. Yes I'm getting to the question...

If I wire this to my starter switch, would that make sense, instead of installing yet another switch?

It's only when I'm starting the car that I need the electric fuel pump. I want it off when the engine is actually running. This would ensure I don't forget it because the starter switch is spring loaded. It makes sense to me, but that's what concerned me.

Attach file:

---

  (52.44 KB)


  (47.72 KB)

If I wire this to my starter switch, would that make sense, instead of installing yet another switch?


For my two cents, I would put in the extra switch for two reasons. First being if you actually experience vapor lock when driving you will want to run the pump without the starter and two, a solenoid or other coil can have a huge inductive kickback or voltage spike when current to it is released. Depending on type of pump & where you wire it, the pump could be damaged.

If leaving it on concerns you, then a spring loaded toggle or pushbutton switch is the answer. Downside to either would be the need to hold it while driving should the need arise.

I use a toggle switch as I want to pump the fuel up to the carb. before I hit the starter button. Also I installed the 6v pump directly into the fuel line as the manual pump pulls threw it even when it is off.

Thanks, Howard.

I think one of these articles mentioned a switch that did both.

I found it. It's a 3-way testing toggle switch. Off, Spring-tensioned On for priming, and an On for continuous use. In the same paragraph the article also warms not to connect to Starter switch because it's possible to prime the carburetor without having the ignition on and no current to the distributor.

So a 3-way toggle is what I'll look for today. That and a shield of some kind to keep the pump, valve and gauge clean.

EDIT:
Thanks, Saltydog,

I'll add a switch. There were two main reasons in the article for not adding the pump directly in the fuel line. One is the pressure is higher than the specs for older carbs, like 7-10 PSI, but claasics' carburetors need typically 3-5 PSI. 7 pounds overwhelms the float needle and can run the engine too rich. This is corrected by using a fuel pressure regulator in the line, or the setup I have...valve and gauge.

The second reason is, if the diagram in the mechanical fuel goes bad, the electric pump will keep on pumping (if you leave it on), pumping gas into the crank case. It isn't easy to notice until one day you check the oil and it smells like gas and it's over the full line.

Joe, instant expert (I went back and re-read)

Joe, I may be mistaken (often I am), but it seems to me that the way you have your electric fuel pump plumed, it would still pump fuel into the crankcase if the mechanical pump fails. I think the only way to get around this problem is to plumb the electric pump in parallel with the mechanical pump. Someone please check me on this. Thanks.

(o[]o)

Why bother with the "manual pump" at all if the electric fuel pump WITH pressure regulator will do the job???

IF the "manual pump" goes bad to the extent that it is pumping fuel into crankcase then it will continue to do so either with electric pump or no electric pump and regardless of how anything is plumbed.

THe only way to eleminate the possibility of manual pump going bad and pumping gas into crankcase is to eleminate "manual pump" and use only electric pump .

The manual fuel pump also acts as the windshield wiper vacuum pump. I use an electric pump with a seperate toggle switch and without the pressure gauge, and only use it for start-ups after more than a week has passed. Also, for quick vapor-lock problems, then shut it off immediately.

Post 1. 6vfuelpumpSETUP.jpg. (second pic):

I see what appears to be a clear plastic inline fuel fiter (between two brass "T's" and rubber hoses) but no check valve???

My '50 came with an electric fuel pump wired directly to the coil (always on when the engine was running). I re-wired it to the ignition switch with a 3-way marine switch hidden under the dash (off, on, spring-loaded manual hold-on). The pump is simply cut into the existing fuel line, attached back by the tank with no pressure regulator. I frankly don't know why the former owner installed it. The car starts and runs just fine without it being on. Maybe he had vapor lock problems... I don't (I use real gasoline for my Packards, no alcohol). I have used it to prime the carburetor after the car has been sitting for some time but it really doesn't take that much cranking to get the engine to start on its own.

My '49 doesn't have one and, at present, I don't see a need to install one.

My '41 has one but that car is a work in progress and I don't know the status of the mechanical fuel pump yet.

Quote:

Keith, if my understanding is correct, an additional fuel line from the output of an electric fuel pump to a tee fitting on the output of a mechanical pump will allow the electric pump to provide fuel to the carburetor without pumping through the mechanical pump. The mechanical pump's output check valve will prevent fuel pumped from the electric to go back into the mechanical pump. This is what I meant by plumbing an electric pump in parallel with the mechanical. Like I said earlier: Someone please check me on this one.

(o[]o)