| fordmerc | -- 07-02-2010 @ 8:15 AM |
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Has anyone electrically modified a sending unit circuit to improve accuracy? Most recent forum discussion 5/24/10, points out the many problems. Can a resistor be added or the circuit modified to make them more accurate? I have tried 5 old sending units: max reading is around 3/4 full, most read "E" at <1/2 excursion of arm. A new repro reads about the same. (Not all units read the same, just variable inaccuracy)
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| supereal | -- 07-02-2010 @ 9:49 AM |
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That shouldn't be necessary. Many of the repro senders we have seen that don't register properly were mounted incorrectly. Try turning the base of the sender 180 degrees and see if that will improve the operation. Most senders have this instruction in the carton, but others don't. All senders must have the arms either bent or extended to read properly. The position of the slider on the resistor isn't always linear, but careful adjustment will usually fix it. Using a stick, measure the fuel level in then tank thru the sender opening, and adjust the sender until it matches that level.
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| TomO | -- 07-02-2010 @ 5:28 PM |
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fordmerc, How are you testing the units, in the tank or out of the tank with a spare gauge? If you have the original type sending unit and it does not move the gauge needle the full range when out of the car, you can remove the top cover by gently prying it off and then clean the contacts using a good contact or tuner cleaning spray. Be careful to not break fine wires attached to the points. Your gauge may also have problems. Test the gauge by grounding the wire that goes to the tank unit,it should move towards the full mark. Do not leave the wire grounded after the gauge reads full, you could damage the gauge. The original sending units are easier to adjust than the after market ones. If you are testing the unit in the car, you may have a grounding problem Tom
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| fordmerc | -- 07-04-2010 @ 1:15 PM |
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All the units that I have tested were evaluated with the sending unit removed from the tank, then reconnected via wire to the sending unit wire and grounding the base of the unit. The fuel gauge reads full when I briefly ground the wire to the sending unit. My original unit is too rusty to use. I may try to adjust one of the other original type units as suggested (they were borrowed from a friend to test and I'll need permission to take one apart.)All of the units exhibit varying degrees of corrosion.
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| TomO | -- 07-05-2010 @ 8:16 AM |
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What is the year and type of vehicle that you are working on? I may have a good used sending unit for it. Tom
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| fordmerc | -- 07-05-2010 @ 10:57 AM |
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'39 Mercury Town Sedan is the problem child
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| TomO | -- 07-06-2010 @ 7:46 AM |
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Send me a private message with your E-Mail address and I will send you the details of the sending unit. Tom
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