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

Hello All,

Since straightening out my rear end problems, I've been making test runs and working on sorting out a handful of other issues. Ones that keep popping up are random stalls that make me think of vapor lock. She'll be a no start, no how but let her sit 30 mins or so and she fires right up.

I'm going to go backwards and return to the mechanical pump the PO bypassed when he installed an electric. Got Feltz working on a rebuild and thought I'd see if anyone could ID that funny bulb on the vacuum side. (It's just to the L of the upper hose barb in the pic.) Could it be a micro-mini vacuum canister for buffering or collecting vacuum?

Anyone have any tips on installing the rebuild to minimize vapor lock? Wrapping the lines, installing a heat shield, rigid v. hose, etc...

Thanks, Michal

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It's an air dome and should be on the outlet side. It's just a column of air which compresses to eliminate or absorb the diaphragm pulsation from the pump -- like a similar arrangement in many home plumbing systems to eliminate water hammer in the pipes.

Check for gas leaking or percolating from the carb when stopped. It may be flooding the engine when trying to restart soon. Is there a large fiber insulation gasket at the base of carb to keep it from soaking up all the direct heat from manifold. Some cars had them and some didn't.

Thanks Howard, makes sense. Now, I've got a vacuum line going directly from the intake manifold to the wiper motor, which I'll move from the manifold to the pump barb with the dome... now where would the inlet-side lead to? Some sort of filter?

Michal

Michal,

The lower part of the pump with the dome is the fuel section.
the vacuum section is the upper part.

Brian

I just went through all this with the same exact pump on my 50. (And another spare pump i had). Both pumps had ran fine on motors about a year earlier.

It looked good inside and bench tested ok, but would only really pump if there was enough gas in the carb to fire the motor. Since everything was dry, the starter wasn't moving it fast enough for the weak pump to prime the system.

I swapped it for a pump from Max Merritt that looked and worked great for $125. No issues in the limited use since then. I also have a tiny pressure regulator (1-5psi in 1/2psi increments) to install later and a clear glass bowl filter and a 1-15psi small liquid filled fuel gage on the line between the pump and the carb.

The front side of the vacuum pump outlet goes to the manifold, the other side goes to the wiper motor. The vacuum pump is in-line between the manifold and wiper motor.

The front line on the fuel side of the pump goes to the carb, the rear line on the fuel side of the pump goes to the fuel inlet.

Of course, bottom of the pump is fuel pump, and top of the pump is vacuum pump.

You can see my adventures here, near the bottom of this page after me whining about starter issues

https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=6337&viewmode=flat&order=ASC&type=&mode=0&start=0

A little confused with your question. The gas and vacuum are totally separate. Supply from gas tank goes on bottom inlet and then dome and outlet to gas filter if you have it or carb.

Vacuum goes to top section. Manifold to vacuum outlet and wiper motor to vacuum inlet. If they are not labeled, just move the lever to diaphragms. The one that has suction goes to motor. That puts the vacuum section in series between the manifold and motor. When intake vacuum is strong, it pulls thru the valves and pump to run the motor. When intake vacuum is weak, then pump becomes stronger and supplies vacuum to motor and exhausts air to manifold until the intake becomes stronger again.

Picture worth 1000


Note: your air dome is on the opposite side of the pump than mine, so your fuel inlet/outlet may be different. Otherwise, that looks spot on as the same pump.


Edited: update pic with my inlet and outlet.

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Ah, great clarification. I had the image that the dome was on the vacuum portion, not the fuel. I'm right-side up on it now... thanks much. I do have the glass filter which is how I traced the delivery problem to vapor-lock. With a full tank of gas and the electric pump running, I wasn't spilling gas when I loosened that glass bowl. I read a bit about electric pumps preferring to push than pull but didn't want to bother relocating it to see for myself.

I'm a believer that this car came from an era of high levels of engineering, parts production, and assembly. Cost cutting was much more mild then than now, eh?

Michal

I'm glad it is making sense to you because I'm still confused. To me, that pump looks like the bottom section is on 180 out or is that a totally different pump than this one.

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HH56 could totally be right. Would explain why the air bulb is on the opposite side as my pump. Maybe someone rebuilt it and couldn't get it right and switched to electric?