gas tank sending unit

dick lyons

dick lyons

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

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dick lyons said:
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.
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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
 
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?
 
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?
 
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 said:
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.
Click to expand...
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.

dick lyons said:
the dash fuel gauge is adjustable???
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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.
 
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.
 
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.
 
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?
 
yes, I have grounded the sender housing. regarding the dash gauge, is it adjustibe, if so, how is it done?? thanks, dick.
 
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.
 
19Fordy said:
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.
Click to expand...

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.
 
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.
 
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