gas tank sending unit

[dick lyons]

hi all, my 48 coupe dash gauge reads E all the time. I read all the searches on this. I grounded the tank sender and the dash gauge went to full. I turned off ign. switch. guys, has ENYBODY replaced thiers with something that really works, and if so, where did you buy it?? thanks, dick.

[19Fordy]

Dick, If you discover some good news, please let us know.

As you may know you can carefully pry off the top of the sending unit and carefully adjust the little star wheel you see inside with a small screwdriver.

[Pete]

If you can't find an OEM one, most all of the hot rod suppliers have them
Summit, Jegs, Speedway Motors.

[dick lyons]

1940, I read on one post where a member slid a piece of paper thru points or someplace under the top cover and made his old one work? I will try that. to pete, my reply to him is,no one so far has had ANY success using these off shore replacement units. I guess we are all between a rock and a hard place. anyone one else have an idea?? thanks, dick.

[dick lyons]

I should also say the copper float does not leak. and tank is about half full. I also need to know in what direction to adjust the star wheel. thanks for your replys. dick.

[19Fordy]

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Dick, I forget which way I turned the little star wheel in the sending unit. Just be sure to "mark"it so you can always return it to its original position. You can use a small blade flat screw driver. Adjust it only a teeney -weeney amount at a time. I colored the star wheel with a black magic marker and then made a little scratch on it.Here's some photos.

[Neal]

Originally Posted by dick lyons

I should also say the copper float does not leak. and tank is about half full. I also need to know in what direction to adjust the star wheel. thanks for your replys. dick.

The float may not leak but it also may not float.

I bought a replacement float from MAC's a few years back and found that the float would float in water but not in gasoline. Just too heavy.

Neal

[Marv]

If you find those tank units at $1.75 would you please pick me one up to. Marv

[FRANK PKNY]

I have tried several after market units . Both id not work, one worked for a while and quit. I did find an old one at a swap meet . How do you get the top off. Just pry it up with a screw driver. I should think you would have to seal it somehow from the elements?

[dick lyons]

19forty, are you sayind that what you did resolved your problem? and I guess it took a LOT of putting in and taking out the unit?

[19Fordy]

Dick, I really don't know if removing the top and adjusting the star wheel AND "rebending" the little metal prongs that hold the tiny carbon resistor in place so that the resistor was held in position nice and snug did help or did not help as I was also rebending the little metal tabs on the sending unit that control the total up and down movement of the float. I also cleaned the points with some 600 emery paper. With the sending unit hooked up outside the tank I checked the dash gauge reading by moving the float arm all the way "up" and then "down". I should have made each modification - one at a time. I finally got the gauge needle to read 7/8 full when the tank was really full and 2 gal left when the needle on the gauge first hits the empty mark. I also ran a ground wire from the sending unit to the frame. The entire experience is pretty frustrating as it's all trial and error. Make sure your battery is fully charged while doing all this. I did not attempt to adjust the fuel gauge in the dash.
Oh, one other thought. Make sure your float does not have a hairline crack to absorb gasolene. It would be interesting to know what the reading is of that carbon resistor inside the sending unit.

[dick lyons]

the dash fuel gauge is adjustable???

[Flat Ernie]

Originally Posted by dick lyons

1940, I read on one post where a member slid a piece of paper thru points or someplace under the top cover and made his old one work? I will try that. to pete, my reply to him is,no one so far has had ANY success using these off shore replacement units. I guess we are all between a rock and a hard place. anyone one else have an idea?? thanks, dick.

I've made every one of them I've used work satisfactorily. Please search on here - there are folks who adamantly believe it is impossible to make the replacement senders work at all. There are others who think you can't get them accurate.

The problem is the senders are universal and the float arms need to be adjusted carefully for each application. Throw in the fact many are being installed in 12V systems with (in my opinion) less than ideal gauge conversions/step-downs and it aggravates an already delicate situation.

Originally Posted by dick lyons

the dash fuel gauge is adjustable???

Yes, all of them are. The little star wheel bends the spring so it takes more/less heat to move the needle attached to the bimetallic strip.

[D. Jones]

The gas gauge on my 45 pickup wouldn't read more than about 7/8 full or less than just above empty. It turned out the tank sending unit had been replaced with one that had a slightly longer arm for a bigger tank which caused the gauge to read wrong. It took me a while to figure that one out.

[19Fordy]

Flat Ernie, I always read your posts relating to problems with fuel tank sending units and want you to know that your research , tenacity and willingness to share your info. is really appreciated. Perhaps someday there will be a surefire way solve this problem.

[waterboychuck]

I'm certainly not an expert on this issue but have you tried installing an additional ground wire from the sending unit screw to a good ground on the car?

[dick lyons]

yes, I have grounded the sender housing. regarding the dash gauge, is it adjustibe, if so, how is it done?? thanks, dick.

[dwaynec]

My first experience with this is the repop sending unit in my car does work. It took a little patience in getting the float rod properly bent, but now when I fill the tank it says full and when it says empty it takes about10 gals to fill. By the way, this is in a 37 sedan.

[Flat Ernie]

Originally Posted by 19Fordy

Flat Ernie, I always read your posts relating to problems with fuel tank sending units and want you to know that your research , tenacity and willingness to share your info. is really appreciated. Perhaps someday there will be a surefire way solve this problem.

Thank you...after answering the same questions over and over, you get better at it! Whether you're right or not!

I'm tempted to write a 12v conversion book...what's currently on the market seems to be inadequate for the majority of folks.

[JSeery]

Ernie, sounds like a good idea! Almost all of the books I get on restoration, wiring etc. are little to no help. You get all of this background and general information and almost nothing of practical use.

[19Fordy]

Ernie, PLEASE go ahead and write that 12V Conversion book. Just do a little bit each month and pretty soon it will be done. Since it will be about "conversion" make it a very enjoyable religious experience with plenty of diagrams, verbal steps and explanations. I think a lot of folks get confused with schematics so lots of pictorials would be great.
Seriously!

[koates]

dick lyons, Sliding a piece of paper between the sender unit contacts was probably meant to explain sliding a strip of fine wet & dry type paper (1200) doubled over through the contacts to clean them. You cant leave a piece of paper between the contacts as that would insulate them an render the sender useless. The winding on the bi-metal strip inside the sender unit should be inspected to make sure it is not burnt, overheated or broken as this will also render the unit faulty. DONT BEND anything inside the sender as that would upset the opening and closing frequency of the contacts. Only do tiny adjustments on the star wheel as explained on other posts. Before altering that star wheel a time period of several minutes should be allowed between adjustments to allow the bi-metal strip to heat and cool when testing the gauge readings. This is a fine instrument and if you are not very proficient at delicate repairs it is better to leave it alone as you may bugger it up. The dash fuel gauge is generally regarded as non adjustable, so don't mess with it unless you know gauges. Previous posts on these King Sealy gauges explain how they work, but they do not work as designed by using a modern replacement variable resistance sender unit. You could try using one and might get lucky if it works correctly but don't bank on it. If a car is running a 12 volt system conversion and a voltage reducer/regulator has not been fitted to the gauges it is possible that the gauge and tank sender bi-metal windings have been overheated and damaged or burnt out. These are 6 volt gauges and never designed to operate on double that voltage. Some will say theirs work OK on 12 volts without a reducer but I say they have been very lucky so far. Regards, Kevin.

[dick lyons]

Kevin, thanks for the info. My car is still 6 volts. I will try what you have said. I will be very careful not to mess this up. Thanks to all for the input to this problem. Dick.

[Flat Ernie]

Originally Posted by koates

Previous posts on these King Sealy gauges explain how they work, but they do not work as designed by using a modern replacement variable resistance sender unit. You could try using one and might get lucky if it works correctly but don't bank on it. If a car is running a 12 volt system conversion and a voltage reducer/regulator has not been fitted to the gauges it is possible that the gauge and tank sender bi-metal windings have been overheated and damaged or burnt out. These are 6 volt gauges and never designed to operate on double that voltage. Some will say theirs work OK on 12 volts without a reducer but I say they have been very lucky so far. Regards, Kevin.

The gauge itself doesn't "know" what voltage it's supposed to operate in, but it has an operating range for whatever it is measuring. Often, these are physical limitations on the gauge itself. Virtually ALL gauges are ammeters of some sort. Double the voltage and leave the resistance/impedance the same, and the current doubles. Now the gauge, without a reducer of some sort, is outside its operating range and may be damaged, that much is true.

But if you're trying to regulate the amount of current through a gauge to render a reading of some sort, there are a few ways to do this. The King-Sealey way was to introduce full system voltage (6-8VDC) in a chopped manner (on/off switching of the bi-metallic strip moving contacts). "Modern" guages regulate current by changing the resistance and introducing lower than full system voltage continuously. So, yes, modern variable resistance sending units can be made to work perfectly fine with KS gauges.

Besides the ammeters, the only early Ford gauge that I'm aware of that does not require a voltage reducer is the 1940 BATT gauge. The early Ford service bulletins tell us that entire circuit is 60ohms, so we can run full system voltage to it and add an additional 60ohms in series with the gauge and it should operate as intended. If you regulate voltage via a step-down or CVR to the BATT gauge, it won't read properly.

The rest of the gauges require a step down of some sort. I don't care for choppers or dropping resistors and greatly prefer solid state CVRs. The L7806 will provide a steady 6V to the gauges and they're pennies to buy.

The gas tank sending units of modern design can be made to work reasonably well. An original KS is probably preferable, but given that they're not reproduced and originals are often missing or broken, the aftermarket replacements are more than acceptable for the overwhelming majority of applications. The challenge, as previously stated, is that they're of a universal design and the float arm must be very carefully adjusted to obtain reasonably accurate readings at each end.

Adjusting the gauges via the star wheels should be a last resort. Disassembling a KS sending unit to clean the contacts is a worthy endeavor because if it's not working now, you're probably not going to hurt anything anyway. Just be extraordinarily careful you don't bend anything internally - use some very fine wet/dry sandpaper/polishing paper and clean well when finished.