1940 Ford gas Tank Sending Unit Question

:)gidday fourdy,,all the questions on these replacements have been bad ,everyone seems to have had a problem with them ,get a nos one i know that they are expensive but thats the way to go if you intend to keep the car.i believe stacy in texas has nos but not cheap trev nz
 
Thank you all for the info. Bruce, I read all the posts you referenced and they sadly revealled the truth. No sense wasting money on junk replacements. I will be taking my old sending unit apart. Perhaps turning the little star wheel inside will make it work better.
 
You can bench test your sending unit if you have a working gauge. I cleaned my original up and it has been working so far. Figured why waste the money on junk reproductions as well.
 
19Fordy, I hate to disappoint you, but there is no star wheel in the original sending units.

Bench test your sending unit. If it reads full with the arm all the way up, half full when halfway down and empty when all of the way down, it should work fine when in the car.

To check the gauge, temporarily ground the wire going to the sending unit and the gauge should move towards full.
 
Hmmmmm....... I just used my brake spoon to remove the top cover on my sending unit # 01A-9275-A and look what I found. This is the same sending unit that was in the car when I bought it in 1963. It is amazing to see 1940 technology that didn't change until the mid-50's. I wonder what the function of the little starwheel is and I also wonder what the resistance is of the carbon resistor. I wish I was more knowledgeable in electronics as I bet a more modern version of this unit could be built that would work in perfect harmony with the stock gas gauge. If anyone knows the functions of the starwheel and resistor, please chime in. Click on the photo once to isolate it and then click on it again to enlarge.
 

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I just recently posed this question myself. I bought a '40 out of Florida and dealt with this issue. My '40 had a cork as the 'floater' and it was soaked and didn't float, i.e. no buoyancy! My gas gauge did not work properly. So, I said 'what the heck, I'll replace it'. I bought a gauge from the local 'ford store' and it turned out to be from Vintigue. It did NOT perform close the being accurate. After reading the 'treads' on Ford Barn, I decided to 'chuck it' passing the cost off as a 'Friday night pizza'! I bought two corks from the Model A catalog and 'fixed' them together. BINGO, this give me the buoyancy needed; I am now in business.............. :-)
 
Mr. Spiker, Original 1940 sending units didn't come with cork floats. Do you know what your sending unit is from or where to get one? Thanks.
 
Search my posts on this topic. I have made every aftermarket unit work successfully with 12V using original gauges.
 
I was shocked also to find that it was a cork float unit. I was expecting to find the brass float. It seems like everything is original on the car, i.e. engine, wheels, etc. But, fortunately, the unit works properly with my assembling two Model A corks to equal the length of what I found on my tank unit.................. It could be that some where along the way the gas tank was changed?
 
My 40 Coupe pictured in my avatar has a cork float ,as far as I know it's original. The gauge works good regardless . My 39 Zephyr also had a cork float in it .
 
Flat Ernie said:
Search my posts on this topic. I have made every aftermarket unit work successfully with 12V using original gauges.
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Hi Ernie, I found your post here. http://www.fordbarn.com/forum/showt...hlight=1940+ford+gas+tank+sending+unit&page=3 You mention that you do make the variable resistance replacement sending units work with the stock gas gauge. Is this accomplished by somehow adjusting the variable sending unit or by tinkering with the dash gauge? You also mention a "gear set up". Is that inside the dash gauge? I am really hesitant to take my gauge apart as I am afraid of breaking it. Scaredy cat, I guess. I am using a CVR as you recommended. My 40 BATT gauge is still working fine thanks to you.
 
19Fordy said:
Hi Ernie, I found your post here. http://www.fordbarn.com/forum/showt...hlight=1940+ford+gas+tank+sending+unit&page=3 You mention that you do make the variable resistance replacement sending units work with the stock gas gauge. Is this accomplished by somehow adjusting the variable sending unit or by tinkering with the dash gauge? You also mention a "gear set up". Is that inside the dash gauge? I am really hesitant to take my gauge apart as I am afraid of breaking it. Scaredy cat, I guess. I am using a CVR as you recommended. My 40 BATT gauge is still working fine thanks to you.
Click to expand...

I've used them as-is, no adjustment really - the trick is getting the float arm the length you like. The range of motion truly isn't correct on these - this is a problem with the mechanical side of the sender, not the electrical side. You can adjust the arm so it's accurate at empty or accurate at full, but I haven't been able to get both. I prefer accurate at empty and actually, made mine hit full travel about an inch above the bottom of the tank, so even when it's on 'E', I still have a little bit left! This means my gauge won't quite read full when the tank is full. The arm simply can't move up enough...mechanical issue. You might be able to shorten the arm up a bit more and get it closer, but I was happy with mine.

I didn't adjust my star-wheel gear (and they're in the gauge) at all - they just change the tension on the bi-metallic strip so it requires more or less current to move it. I think you could play with it a bit and get closer on your "inaccurate" end of the gauge, but haven't felt a need...and you'd only move it a tiny, tiny bit and check.
 
19Fordy, if the wires in your sending unit are not broken, it should work. Did you try the tests mentioned?
 
TomO said:
19Fordy, if the wires in your sending unit are not broken, it should work. Did you try the tests mentioned?
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Hi Tom, The wires inside the sending unit are not broken and I did perform the "tests" as mentioned by others. At this point I got the gauge to indicate full when the needle is just in front of the FULL line. I am going to wait until the gauge reads 1/2 and then fill the tank to see if it was an accurate reading. The tank I am using is a "plastic" aftermarket that holds 15 1/2 gal. I have a separate wire running from the sending unit to the frame.
 
If you have the plastic tank and are running 12 volts you can get a sender from Yogi's that will work with your stock gauge. I think they are about $30
 
TJ said:
If you have the plastic tank and are running 12 volts you can get a sender from Yogi's that will work with your stock gauge. I think they are about $30
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Thanks, but my CVR reduces the 12V input currect down to 6V so the stock Oil, Temp, and Fuel gauge can still work.
 
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