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 Post subject: Beck Fuel Gauge
PostPosted: Sun Oct 09, 2016 1:28 pm 
356 Fan

Joined: Tue Dec 11, 2012 8:56 am
Posts: 120
Location: London and NW England
Can anyone explain to me how this works , and what are the common reasons for it not working ?

I have one fitted to my car , gauge dial is calibrated in fractions . It under-reads by a big margin , and pushing the little button does not seem to change anything . Should I be looking in the tank with the filler cap removed while someone else presses the button , to see what if anything is going on ?

Meantime am working on calibrating a dip -stick !


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 Post subject: Re: Beck Fuel Gauge
PostPosted: Sun Oct 09, 2016 2:31 pm 
356 Fan
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Joined: Wed Mar 26, 2008 7:21 pm
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Location: NE Michigan, lower penn.
Could be the rubber pressurizer has deteriorated. I think you can remove the plunger assembly from the pipe and repair/replace the pump. Near as I recall, there are 2 tubes in the tank - one near the top and one near the bottom. When you depress the button several times it pumps the gas out of one tube and the gauge reads the pressure difference. Mine always moved up whenever I filled the tank, but not to full. Had to pump maybe 10 times to get an "accurate" reading. Best to depend on the trip meter to know when it's time to refuel.

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 Post subject: Re: Beck Fuel Gauge
PostPosted: Sun Oct 09, 2016 5:20 pm 
356 Fan

Joined: Wed Mar 26, 2008 12:06 pm
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Location: Orinda, CA
The Beck system reads the "head pressure" of the fuel in the tank. The small pump is used to pump any fuel out of the tube that goes into the tank so that you are reading the full "head pressure" of the fuel. Originally the pump also had a check valve function so the pressure was retained and did not leak out. When these systems were new you only had to use the pump after you filled the tank, or if you went from a high altitude to a lower altitude, and even then it was only to correct for small errors in the reading.

If yours is reading low, and is not changed by using the pump, it sounds like the tube is partially filled with gas so that you are reading only the head pressure of part of the tank, and the pump is not working to empty the sense tube. One point to check...you need to remove your finger from the pump after each push as the inlet to the pump is in the center of the button. If the pump is working correctly you will eventually hear air being pumped out of the sense tube and bubbling up through the tank.

The other possibility is the gage itself is not reading correctly, but they tend to be pretty reliable. If you start to check the gage itself be very careful as they are a very low pressure gage as full scale is only around 14 inches of gasoline which is around 8 to 10 inches of water or less than 1/2 psi.


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 Post subject: Re: Beck Fuel Gauge
PostPosted: Mon Oct 10, 2016 2:19 am 
356 Fan

Joined: Tue Dec 11, 2012 8:56 am
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Location: London and NW England
Aha ! Thanks guys , I think I understand it now.


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 Post subject: Re: Beck Fuel Gauge
PostPosted: Fri Jan 27, 2017 12:35 pm 
356 Fan
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John

over the years I've restored about a dozen of these sending units

Even with the system working correctly the reading is non-linear and very rarely read above 3/4 of a tank and only holds the reading for a few minutes then falls back to 0 . ( normal)


If your bellows in the pump is cracked you can take the pump apart and coat the bellows with some 3m rubber cement 2 or three coats over a few days works well , mine is going on 10 years with the rubber cement fix

To check the gauge hold it away from your face at arms length and blow towards the back of the gauge, have someone look at the face of the gauge. If it moves your good. if it doesn't move slowly start bringing it closer to your face and keep blowing. if you get within a ft and still nothing the gauge is probably bad . Never blow directly into the back of the gauge. it will screw up the internal linkage bend or knock it out of alignment .( sometimes this is repairable) ..

another common problem is fuel making its way back to the gauge . this is caused by a clogged vent in your tank or a crack in the gauges eddie tude ( bellows ) ( sometimes fixable but you usually only get 1/4 usage out of the gauge better than nothing ) i do have a some spare parts .

Most sending units i have seen have cracked bells on the bottom of the sending units so they wont build pressure . so the gauge wont respond ( fixable new copper bell or silver solder the existing bell )

its also very common for the capillary tubes to be full of varnish . ( fixable.. try and pump MEK or acetone through the lines or replace the cap tubes if needed )


When i restore them i set them up so that the bell bottom is about a inch off the bottom of the tank, This way when you press the pump to check your fuel level if nothing happens you know your below two inches of fuel..

If you are in need of a rebuild, I charge between $250 and $500 depending the problem. i also clean it up and buff it out so it shows nice and replace the plastic coating if needed ( new plastic sleeve is more gray less silver than the original still better than nothing ) . If your interested i can take a look at your stuff ...pm me. Send the unit to me with a return pre paid label. i will give it a once over give you my free opinion and a price to rebuild .. yes or no the worst you are out is cost of mailing ..if you want to give it a whirl on your own, feel free to email or text me pictures ill be happy to help with any questions.

Regards Ned
55 continental cab


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 Post subject: Re: Beck Fuel Gauge
PostPosted: Sun Jan 29, 2017 5:01 pm 
356 Fan

Joined: Wed Mar 26, 2008 12:06 pm
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Location: Orinda, CA
Ned, I have to disagree with a couple of your points. You said the gauge "only holds the reading for a few minutes then falls back to 0 . ( normal)", this is incorrect as the system when it was new had a check valve function (in the pump as I recall) so the gauge retained its reading and did not return to zero, at least not within minutes, maybe over a few days. Also the large diameter bell at the end of the sense tube is there, I believe, to dampen the gauge reading and to make it less sensitive to temperature changes, a crack in the bell will reduce the accuracy of the gauge and will make it more susceptible to temperature changes but will not prevent it from building pressure. A crack at the top, where the tube is attached to the mounting plate which bolts to the tank, however would cause it to not be able to be pressurized.
Alan


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 Post subject: Re: Beck Fuel Gauge
PostPosted: Mon Jan 30, 2017 4:22 pm 
356 Fan
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Alan no disrespect i think you may be confusing the beck system with possibly another system ?
The check valve and the pump simply delivers air to the end bell via the capillary tubes .. and yes if the check valve leaks it will cause the pressure to equalize (they all leak some in 30 seconds some take a little longer ) .
. There is no sense tubes in the beck system .
The beck system is simply two unmolested open ended capillary tubes running down to a open bottom end bell just like an old diving bell ( open on the bottom ).
one capillary tube pumps air into the bell the other open ended cap tube runs back to the gauge and delivers the 0-.5 psi of pressure for the gauge to display a reading .
If the thin walled copper bell is cracked and most of the ones i have worked on have been , it cannot hold air therefor it can not build a differential pressure and the gauge will stay at zero . The bell is there simply to collect air ( air sitting below a head pressure of fuel ). as you drive the car, some of that air under the bell is lost by sloshing fuel it forces the air out from under the bell thus showing a lower reading on the gauge. although most air is lost bleeding back through the pump and check valve .. Temperature
will play no role in the fuel level as the entire system is open to atmospheric pressure and every time you fill the bell with air everything is reset .
The tube connecting the top of the sending unit and the lower bell is only there to support the lower bell and hold the capillary tubes in place its basically an extension of the bell .
If the vent is clogged and the pressure in the tank rises above atmospheric pressure. The fuel will be forced to the path of least resistance usually the needle valves or back through the cap tubes up through the check valve and out through the pump but if the check valve is actual doing its job. The fuel will back up into the gauge or over pressurize and ruin the gauge if the pressure goes above .5 psi

Regards Ned

Happy Connecting. Sent from my Sprint Samsung Galaxy S® 5


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 Post subject: Re: Beck Fuel Gauge
PostPosted: Mon Jan 30, 2017 11:12 pm 
356 Fan

Joined: Wed Mar 26, 2008 12:06 pm
Posts: 936
Location: Orinda, CA
Hi Ned,
There may be some variations in the construction of the Beck gauges, but the one that was in my car was built such that the brown tube shown in your diagram (the line from the gauge) connected to the large (1/4inch or so) sense tube that went down in the tank. The pump line was as you show. See attached photo of the bell area and diagram from the mounting instructions. If the system is installed in an empty tank and properly connected so it won't leak, the large sense tube remains filled with air and would respond to the head pressure of the fuel regardless of the bell. If there is a slight leak in the gauge internals or in the gauge connection I suppose the large tube could fill with fuel, and the gauge would only work if the bell would fill with air. A small leak in the gauge or gauge connection would also cause the loss of reading such as you are seeing. In fact thinking about it, a leak in the pump or check valve has no effect on the gauge reading as the air is supposed to be trapped in the bell.

As my system has been removed from the car I will test in in a jug of paint thinner to verify that it holds the reading for a long period.

I will also attach the mounting instructions for the Beck gauge if anyone can translate the German, it may discuss operation.
Alan


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 Post subject: Re: Beck Fuel Gauge
PostPosted: Tue Jan 31, 2017 10:18 am 
356 Fan
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Alan
ok now i see. we are both talking about the same thing, its not rocket science its simple physics :)....
The tube you are calling the sense tube confused me . yes it is an extension of the bell as previously mentioned . If you shine a light directly into the 1/4 inch tube you will probably see the other capillary tube within a 1/2 inch or so of the bottom of the bell.Under perfect conditions the location of the the cap tube i'm guessing is irreverent as any spot in the tube and bell should be the same pressure
. Given the state of your bell one would think. the unit wont trap air in the bell and tube to build pressure, fuel will fill bell. the air will leak out. pressure will equalize and the gauge reading will go to zero. Alan not looking to disagree with you, just stating what I've seen over the years. and read on the list regarding fuel backing up through the pump and leaking at the gauge.

Although i am very curious about the end of the gauge connected cap tube location .. as i stated all the ones i have repaired 9 to be exact the tube ended close to the bottom of the 1/4 inch tube .. seeing your cut sheet .. i'm thinking the tube ending closer to the top of the 1/4 inch tube would most-likely allow the system hold a reading longer...
i have a spare one kicking around i'm going to take it apart and shorten the cap-tube to see it works better than the one i'm currently using .



Regards Ned

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 Post subject: Re: Beck Fuel Gauge
PostPosted: Tue Jan 31, 2017 11:01 am 
356 Fan

Joined: Wed Mar 26, 2008 12:06 pm
Posts: 936
Location: Orinda, CA
OK Ned, it is test time! I filled a gallon jug with mineral spirits and inserted the sense tube. Photos of the gauge reading before and after insertion attached. Will check back periodically and see if the reading changes. I also checked with a light and do not see the gauge tube at all looking into the 1/4 inch tube, so it is definitely somewhere higher up in the system. And yes the bell on the system I have is cracked.


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Last edited by Alan Hall on Wed Feb 01, 2017 12:56 pm, edited 1 time in total.
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 Post subject: Re: Beck Fuel Gauge
PostPosted: Tue Jan 31, 2017 12:11 pm 
356 Fan

Joined: Wed Mar 26, 2008 12:06 pm
Posts: 936
Location: Orinda, CA
One hour in, no change in reading. Heading out for the day, but will check again this evening.


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 Post subject: Re: Beck Fuel Gauge
PostPosted: Tue Jan 31, 2017 8:33 pm 
356 Fan

Joined: Wed Mar 26, 2008 12:06 pm
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Location: Orinda, CA
Just got home and checked the gauge, 10 hours and still holding with no leak down. Ned if your gauge is not holding the reading, I think it must be due to a leak in the gauge capillary line or the gauge connection or the gauge internal bourdon tube or bellows. I don't have any other complete Beck systems but I do have a couple other Beck gauges. I will try to find them and check them for internal leaks.


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 Post subject: Re: Beck Fuel Gauge
PostPosted: Wed Feb 01, 2017 2:26 pm 
356 Fan
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Alan
mine hold as long as the car is still. Once the fuel starts sloshing around it looses the reading . I really believe the issue is the end placement of the gauge connected cap tube .. The higher up on the 1/4" pipe the better off you are . all the ones i have worked on both cap tubes were relatively close to one another usually with in a 1/2 inch of the bell.. i bet your gauge connected cap tube is located high in the 1/4" tube .. looks like i now have another thing to play with prior to spring ..
Regards Ned

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 Post subject: Re: Beck Fuel Gauge
PostPosted: Wed Feb 01, 2017 8:45 pm 
356 Fan

Joined: Wed Mar 26, 2008 12:06 pm
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Location: Orinda, CA
Ned, If I understand what you are saying, your gauge reads correctly after pumping air into the bell and holds steady at that reading, with no leak down if the car is stationary. This would indicate that the gauge capillary tube and gauge are leak free. But just driving around causes the gauge to drop to zero in short order, a few minutes at most. If this is correct it sounds like the gauge capillary tube is full of gasoline to the tank level because if it was full of air just driving should not cause the pressure to drop that quickly, or drop at all for that matter. Before you perform surgery on your system might I suggest the following. With the tank as close to empty as practical try unscrewing the capillary from the gauge itself which should allow any gasoline in the tube to drain back into the tank (it may take a while for it to drain back because of the small capillary size). After sitting a while then re-connect the gauge, pump any fuel out of the bell, and refill the tank. I suspect the system should work much better. If not you can then proceed to the more drastic mods you are thinking about.
Alan


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 Post subject: Re: Beck Fuel Gauge
PostPosted: Thu Feb 02, 2017 10:36 am 
356 Fan
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The Beck gauge in my '55 holds pressure and gives a reading all the time. After I pump, the reading will most often go up 20 or so percent and that will hold for so long that I don't notice a drop after driving or after being parked for long periods. Just my .02 cents. KTF, Tom

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