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

I am zeroing in on my problem with my '39 Six stalling and it appears I am leaking some air in the pick up tube assembly. Some time ago, someone posted some pictures of the different sending units from the tanks of this era in our cars and, try as I might, I cannot find them (Howard, maybe??) Can they be had or does one have to remake this part?? I am more concerned with the pick-up tube portion of the assembly as my gas gauge sender unit works and I could 'move it over' to a new pick-up tube. Any leads would be much appreciated.

The gas pickup tube is a part of the tank assembly and independent of the sending unit. Remove the sending unit and you should be able to see the pickup in the floor of the tank. If you suspect a hole in it, the problem should go away if you fill the tank enough to completely cover the tube.


EDIT: My error, I was thinking the pickup was the same arrangement as later vehicles. In any case a leak in the pickup tube doesn't seem to fit your failure symptoms so I'd look elsewhere for the cause.

KM Lifestyles has some photos of various senders and could probably repair yours if John Wolf and Co could not.http://www.mykmlifestyle.com/Packard_Fuel_Sender_0YW2.html An earlier 120 manual shows a typical prewar sender but from the KM listings, since several different senders were apparently used how closely yours might match the Packard illustration is unknown.

From the looks of the different models if the sender portion is working and no repairs needed to it then it should be a relatively easy fix to add a new length of pickup tubing. The originals were probably soldered or brazed in place but I would think as long as the damage is below the mounting flange at least an inch or two a portion could be cut off and a new length of metal tube could be joined to the old with a short length of hose and clamps or maybe a brass fitting. Anchoring the bottom might take some ingenuity or stiffening but should be a relatively easy task that could be done at home.

Attach file:

---

  (30.16 KB)

Thanks Dave & Howard. Yes!, those are the pics I was looking for. If I can, let me just update my progress on the stalling issue. After replacing so many things and not having it affect the stalling, I started looking from the fuel pressure regulator, backwards. I had mentioned previously that I had replaced the fuel lines, and what I had done was replace all the rubber hose where it connected to the steel line. I was advised to change the steel line, which I did and it definitely improved the stalling. Now, when I start the car, the fuel filter fills up immediately and the car starts and runs great. We have the pressure reg. set at 3 PSI and the problem now is the car runs the fuel filter out of gas. If the fuel line from the tank is removed, there is a burst of AIR pressure with very little fuel?!?!?!? Our deduction there is that the pump, which is mounted right at the tank, must be sucking in air on the intake side and pressurizing the fuel line when the carb needle seats and doesn't allow gas in. If the line from the tank is removed at the pressure reg (on the firewall) and the pump is activated, a steady, robust stream of straight fuel comes out. Any thoughts or ideas??? I DO feel we are getting very close to fixing the problem. With the new steel fuel line causing much less flow restriction, the car didn't stall doing the same 'circuit' we did before, where it stalled every time. However, with the filter showing a diminishing gas level, I am certain if I took it out on the highway, it would starve for fuel. Way back when I first started to try and diagnose this issue, I dropped the tank and found that the seam at the flange of the pickup tube/sending unit was loose. Initially I thought I had found the problem and that it was sucking air there. Upon further investigation, I determined the pickup tube was one piece going through the flange and when I put my finger over the lower end and sucked on the outflow end - it seemed airtight. Maybe there is a hairline crack there through which air is sweeping when the pump is on max-draw?? Anyway, that's where we're at....

Motors Manual, Eleventh edition says all 39s except the V12 had 4 psi pumps. The output is listed at 4 1/2 for 40s with the same style pump. In any case, nothing was listed back to 35 as using less than 3 1/2 psi.

Since the filter bowl is running dry I would wonder if the regulator is restricting the flow rate as well as pressure. What is the PSI of the electric pump you are using? If it is a typical 5-8 psi pump and located back near the tank, by the time it pushes fuel the distance and thru a filter the pressure may have been lowered enough to not cause problems. Higher output than that would require a regulator but one that doesn't restrict the flow. No idea what you are using but some of the inexpensive regulators have been reported as being erratic at the lower settings. Airtex makes an electric pump specifically for the older carbed cars and would not need a regulator. The E-8902 is a 6v pump for 5/16 lines, rated at 2.5-4.5 psi output and capable of flowing 30 gph.

Is it possible that you have a non-vented cap on the tank? If so, that would cause problems similar to those you described.

I had the same thought Don, but a non-vented cap was suggested quite a while back by Packardbarry in the other thread on this problem. I had assumed the OP checked it out, but perhaps not - you're right, it's a great fit for the symptoms!

Thanks for the replies. Know that I am listening to and heeding ALL the suggestions given by everyone replying. The gas cap venting issue was mentioned a while back and I do have one of John Ulrich's aftermarket gas caps on the car. I got really excited about that one, as Dave said, it was a really good fit for the symptoms. I am currently running with a porous rag, nylon bar-tied to the gas filler neck to eliminate that possibility. (no change)

To answer Howard's question(s) yes it is a 5-8 PSI pump and is mounted at the tank. Being in the hose manufacturing business all my working life, I definitely understand that pressure and flow rate are two different things. I have teed a pressure gauge into the fuel line AFTER the pressure reg. and I can easily achieve 4 PSI at the carb and with 5/16th" tubing and hose, flow should not be a problem.

I have even bypassed the reg altogether and this doesn't seem to change anything. I phoned Bill at mykmlifestyle.com and had a long talk with him. He said my symptoms were 'very curious' to which I have to wholeheartedly agree. The question I keep asking 'why, when I unhook the hose either where it goes into the reg, or at the fuel filter after the reg, is there lots of pressure of combined air and very little fuel???? Where is the air coming from?? If the pump can fill the filter quickly at initial startup yet slowly empties as the car runs, and then there is lots of pressure when the hose is removed???
Bill surmised that, possibly, the pump starts initially and fills the line and then as the engine runs and the carb needle stops the inflow, the pump 'tries' to continue pumping and if air is then drawn into the line because the pump is forced into 'max-draw'and the air is pushed into the positive pressure side of the line, then the carb allows more fuel in, the air slightly depressurizes, then the cycle repeats itself and eventually, the air pressure becomes equal to the output capacity of the pump, and ergo, no more fuel moves forward from the tank. This sounds farfetched, but possible????? But surely, picking up fuel from the tank and delivering it to the carb with sufficient quantity and pressure can't be THAT big a hurdle to overcome, can it?!!?

Why do you have all this complexity of electric pump and pressure reducer as opposed to the simple, proven and reliable mechanical fuel pump?

Is it a rotary electric pump? Just a thought but if so, that type cannot generally be pumped through so perhaps there is some pressure differential between it and the mechanical pump as they likely run at different pressures.