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Vacuum Booster fuel pump NOISE


Ward Duffield

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Hi Group

I just installed a freshly rebuilt, NOS AC booster fuel pump on my rebuilt 218. It is making good vacuum and the fuel flow is good.

The car's rubber vacuum line, which runs  thru the firewall, is connected to a a hard line to the "IN" port of the vacuum pump.

There is another hard line from the pump's "OUT" port to the intake manifold port below the carburetor flange.

The car runs well, BUT the pump is as loud as HELL; it sounds like a bad rod, and I wonder if anyone else has experienced this.

You can feel the rapping thru the suction line when the engine is running.

Thanks!

Ward Duffield

1946 P-15

Pine Plains, NY

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I encountered this on a 50 Plymouth.  The owner was on vacation and 500 miles from home.  It certainly sounded like a bad rod but the collateral clue was that the windshield wipers did not work well.  Turned out that the pump's top cover was loose.   Rather than risk further trouble we replaced the pump with a conventional one and hooked the wipers directly to the manifold.

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Suggest trying this_ remove the out line to the manifold - Plug the port on the manifold leave the pump out connection out (open). Start and see if any change. If not remove the in line to the pump leaving the out line off still.  Repeat the run test for noise?  Trying to see if the noise is coming from the pump or lines/ connected correctly-seems so, but.

 

Best of luck with knock repair! ?

 

DJ

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Hi DJ

Thanks so much for taking the time to respond.

When I removed the steel line from the intake manifold, the noise just about disappeared.

Also, with it hooked up, there seems to be almost no vacuum at the carburetor port which attaches to the distributor advance unit ???

Ward

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Hi DJ

Thanks so much for taking the time to respond.

When I removed the steel line from the intake manifold, the noise just about disappeared.

Also, with it hooked up, there seems to be almost no vacuum at the carburetor port which attaches to the distributor advance unit ???

Ward

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Sorry but cannot find a picture I had of the proper line hookup of the vacuum pump that is stock, as a option.

 

I remember however that the  inlet line To the pump was hooked into the air cleaner that would supply filtered air to the pump. It does Not need a vacuum source as it Is the vacuum source to the wipers. One port of the pump is the vacuum source as that is what does, connects only to wiper motor in port.  Rpms have little effect on the amount of vacuum it will make. When operating properly engine vacuum has 0 effect on wiper speed.!

 

Run the motor with no lines to the vacuum ports on the fuel pump to see which side is the suction side. You may have the lines crossed?

Good luck!

 

DJ

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Quote

A

Quote

 

 

all of that type pump I remember working on back in the day had one port connected to engine vacuum.  The other connected to either a reservoir tank or directly to the wiper motor.    Most connections were made with a short rubber hose between metal parts for precisely the reason you mentioned, noise.  When the engine vacuum is high especially the 'idling' pump is noisy and that gets transmitted/amplified by the long steel tubes attached.

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Hi DJ

Thanks so much for taking the time to respond.

When I removed the steel line from the intake manifold, the noise just about disappeared.

Also, with it hooked up, there seems to be almost no vacuum at the carburetor port which attaches to the distributor advance unit ???

Ward

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36050846_Vacuumdetails.jpg.f7ede4f93f1ffe58ba3dbce7cd97db8a.jpgI searched quite a few manuals and online and never did find any photos of a stock installation; I assumed the air being expelled from the vacuum pump should go into the intake.

In any event, I have disconnected that line and it is quiet so we shall see.

I did also find photos of what I believe to be a cylindrical metal check valve or a muffler (??) in the rubber line to the firewall, but no one seems to know what they are or where to get one.

2020608251__12.JPG.a9e16b061c80060dc58afc06970dece3.JPGIn these cases the vacuum source was the intake manifold, and the cars were apparently convertibles, as I have.

Photos attached.

Since my system seems to work without this part, it is on the back burner. Thanks again for all replies!

Ward

 

 

 

Edited by Ward Duffield
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