TKelly

Vacuum tank trouble

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Hi guys, 

Please forgive me if this has been covered before I did search but couldn't find an answer to my particular question.

 

I am having a problem with my vacuum tank causing the engine in my '26 Essex to stall when it it drawing fuel up from the main tank. Whenever the vacuum tank is drawing fuel up from the main tank the engine runs very rough and stalls unless I hold the throttle open a bit. The engine runs sweet otherwise so would rule out a vacuum leak.

 

The tank in question is a Stewart Warner but does not have the pot metal top it is all tin and has 4 screws that hold the top on.

 

Is there something I am missing or is this just the way vacuum tanks are? 

 

Thanks in advance, Tristan. 

 

 

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Posted (edited)

Sounds like you may not have the right top for it ????   Has it worked well before this ?

 

Flapper valve in the bottom of the top tank, and/or, switching valves, may not be closing completely when it's switched over to vacuum and trying to pull fuel from the gas tank. That will allow some vacuum being applied to the lower tank, over coming the tank vent somewhat and reducing fuel flow to the carb during that cycle, thus dropping the float level in the carb and causing stalling,.... unless you increase vacuum at the carb by opening the throttle more.  

 

Can you post photos of it ?

 

Paul

Edited by PFitz (see edit history)

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Hi guys,

This is the only photo I have of the vac tank it appears to have all the correct parts and is very simple internally, it is not like the other ones with springs and levers etc.

Cheers, Tristan. 

20140529_205332.jpg

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Four  screws to hold the metal top on the vacuum tank was used on Essex cars thru 31 and likely 32.

//

The system works as a two part system.

the outer tank is the reservoir for the carburetors operation.  fuel is supplied to it by the  inner tank thru  the flapper valve.

///////

The inner tank is the Vacuum reservoir and controller  of fuel delivery.

/////////////

The inner tank has the float and it is connected to the  two little "L" shaped rods which open and close the vacuum supply and opening to  atmosphere.

The lower flapper valve is important to seal the inner tank so vacuum can be applied to gas line to tank.

Normally the gas level in the outer tank will help seal  the flapper valve.

/////////////

The top inside of the tank top, needs to have the check valves cleaned,  I use carb cleaner spray.  thay 

Please remove fuel inlet elbow to top of tank, check there is no filter gauze or other obstruction below it.

Next, carefully check sealing surface of flapper valve, It must seal, you may be able to remove clip holding it and reverse the flapper it self.

In addition, there is a small  vent on the top of the tank.  This must not be blocked by the gasket material, it vents the outer tank to let fuel feed to carb.

////////////////

Without personal observation it may appear you are sucking fuel back into the tank from the carb feed line, or just not drawing enough into   the tank.

 

good luck 

 

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Hans his a 26,,I thought they used the 8 screw,correct me if I AM wrong..been known to.

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My response was to his description of the  tank he has.

 

It does have some differences in outside appearance from my tanks. 

 

If someone has documentation of make and model with years  used that could be helpful. 

 

There could have been more than one model of Tank used in a given year.

There could have been changes by owners, even on low mileage vehicles, deemed to be original by some today.

 

 

 


 

 

 

 

 

 

 

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Hi Hans,

I have checked most of the things on your list above the only one I have not checked is the flapper valve which I will do. 

 

The vacuum tank is not original to the car I bought it off a fellow Essex owner and may very well be off a later model but I imagine it should still work being that they all work on the same principle?

 

Thanks for the help, Tristan. 

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Hi Tristan,

 

Is it possible to get a photo of the top, from the photo you posted I can't see a vent tube

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Hi Sasha,

Here is a photo of the top of the vac tank you can see the very small vent which I have checked and it clear. It also has a vent the side of the centre fitting to allow the vacuum chamber to drain into the main reservoir.

Cheers, Tristan. 

20190131_211321.jpg

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Thanks Tristan, 

 

Sometimes the vent gets blocked and that will give to the same sort of problems that you're having, good luck with working it out. 

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Posted (edited)

If the vent were blocked the engine would not run. With a blocked vent, fuel would not be able to  drain from the vacuum tank down to the carb unless air somehow gets into the tank another way.  And, there isn't enough height difference between the vac tank and carb to draw fuel from the gas tank by syphoning action.  

 

Paul

Edited by PFitz (see edit history)

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This tank was on my 29 DB truck. Model 493.It has 4 screws.

73F5CD7D-526F-49B9-B20E-EAF04F6FD4B0.thumb.jpeg.07c0f87f258f97e54ebfcb616003655b.jpeg

 

I found out that the 8 screw model Steward had better parts available and was more common. I choose to purchases one and rebuild with kit from Meyers Parts. It works fine.

F6B331E0-6FEB-4723-BCA9-96F3D7D714AC.thumb.jpeg.2095528027388e9c32f213bcded1a9d6.jpeg

 

 

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The original tank on my 28 Whippet has only 4 bolts also. The inner tank had so many pinholes in it that I have replaced it with an 8 bolt lid vacuum tank that I had. Not sure of the application for the 8 bolt tank but the car ran great with it installed.

Repairing the inner tank on the original setup is on my winter 'to do list'.

 

Bill

 

 

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Hi guys,

Thank you all for your input I have found the issue. It turns out the vac tank must have had a small vacuum leak between where the inner chamber sits in the top of the other chamber I have sealed that and no more stalling. 

Thanks again everyone.

Cheers, Tristan.

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Good find. Thanks for posting what you found the problem was.  

 

Paul

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