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Phil Stark

1928 Cadillac Vacuum Fuel Pump Problems

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My dad originally bought this 1928 Cadillac over 40 years ago. The only problem that we have had is with the vacuum fuel pump. Does anyone know of a solution of how to rebuild this system or (would rather not do this) what type of fuel system to replace the original.

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Is the vac tank a Stewart Warner? There should be at least one vendor who rebuilds those somewhere online.

I have not run one on the road in 30 years, but mine were fairly reliable. I did notice wear on the steel needle (that can be remachined), and the one problem I did have was ultra fine sediment blocking the fuel outlet fitting at the bottom.

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Phil,

Before you tear into the pump check two things:

  • That all fuel lines and filter screens are clean and have no obstructions.
  • That there are no vacuum leaks anywhere.

The pump on my Pierce did not work even after the previous owner rebuilt it, turned out I had both an obstructed fuel line AND a vacuum leak at the windshield wiper. Once those were corrected it ran fine.

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I have a 1928 cadillac. 2nd one I've owned ....first one purchassed in 1971. I had the same problem Don mentioned. Vac leak at wipers. At the firewall you can disconnect the wiper line and install a cap . This will help until you can sort the problem out. The wiper line is the one right behind the line going into the top of the vac tank. At the four line thingy. On the top of the tank on the passenger side is a large cap. Fuel filter (or not) inside. Check for Clogged filter..don't worry if there is none. Don't need that for now anyway. This is the same location I prime my tank from...clear hose and small funnel taped to one end..enough tape wrapped on other to kinda seal hose into hole at tank. When you are not running the car always turn the tank off. I do it EVERY time I turn the car off. Even for quick stops. Call if you want to chat. Rick 704-843-7576

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Lester Wax, an AACA member, rebuilds various vacuum tanks including S-W tanks. His # is 781-784-9083.

I bought a rebuilt S-W tank from his and had very good luck with it.

Martin Lum

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Like UnimogJohn said, vacuum tanks are simple and quite reliable. Rebuilding them is easy... there's nothing to them. The rebuild kit is an example of how simple they are. It's usually a gasket, a couple crush washers, some springs, and a bunch of new screws. The tank is basically a tank within a tank with a float and valve.

Like R-ajax said, always turn the tank off if you aren't going to be starting the car up again in the next hour or so. They tend to leak the gas out if you don't. If you don't have a shutoff valve on the bottom, it's a good idea to install one.

Don't put an electric fuel pump on. You could end up with carb problems because these carbs are only designed to hold back the gravity feed pressure from the vacuum tank.

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I have a '29 Packard running the original Stewart vaccum tank, and have been amazed at how well it has performed, as I know 1929 was near the end of the vacuum tank era. On the flatlands in Texas, no problems at any speed, even in our 95-100-degree summer heat.

I drove this car on the Glidden Tour last year in the mountains west of Denver and was apprehensive about running the vacuum tank out of fuel while climbing. I finally did, but it took about an 8-mile climb at or near full throttle the entire way. I just let the engine idle for a few minutes and was away again. Had I feathered the throttle a little more, I think it wouldn't have run out at all.

In terms of restoration, I had earlier cleaned out the fuel tank and vaccum tank unit, cleaned the strainer at the top of the vacuum tank, ensured that the flapper valve at the bottom sealed tight (I sanded it on a flat sheet of 2,000-grit sandpaper laid on a table), checked the needle valves, and ensured that the brass bushing pressed into the pot metal top plate was firmly in place (these can vibrate loose and cause flooding).

They really are simple units once you understand how they work.

Incidently, it's generally not the vacuum tanks that leak, but the old carburetors. That's why you need to turn the valve below the tank off when the car is going to sit for a while.

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Phil:

can you give us some specifics on what the prob is, IE have you done any tests of the system

Mena

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Thanks to everyone for the posts! Dad has capped off the windshield wiper vacuum line and that seemed to help some. Does anyone know how much vacuum pressure it should produce. He has got a new carb kit ordered to make sure that is not part of the problem.

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