May have found my problem but I'm unsure. I converted to 12 volt and this seems to be when the gauge started reading incorrectly. I tested the positive input at the gauge. I have almost 8 volts. So would that cause the gauge to be off? Have a speedway voltage reducer installed. Anyone know of a better solution or source on a voltage reducer that will be correct. Thanks
Please let me see if I can help. You may be dealing with a sender that isn't doing its job right. The keys there are (1) good float (2) float arm adjusted properly (very important...essential in fact) (3) range of 0 ohms (empty) to 30 ohms (full) and a float that doesn't strike the sides of the fuel tank and bind up and that moves easily throughout the entire range. If you have an aftermarket gauge, I can't stress enough about the float arm adjustment. Please let me know if you need more about that. For most gauges the figures are 5.5" down from mounting surface to the arm pivot point and 5 7/8" between that pivot point and the middle of the float.
If you've been using your fuel gauge with 12 volts, it is unlikely a voltage reducer will solve anything. Inside your fuel gauge you have an hourglass shaped permanent magnet and two electromagnets of varying designs. You can see in the image below. The permanent magnet in the gauge can be affected by higher voltage in that the strength of it can change. Nobody here has the equipment to measure that so nobody really knows how long that change will take but if it happens, your 6 volt gauge will not read correctly at 6 volts any longer. 8 volts might not be a bad number for you. Years ago I built a voltage regulator which is adjustable to any voltage (up to around 12 of course) but I stopped the project. Way too many people have converted to 12v and I'm not convinced a voltage regulator will do a lot for them now. Although the adjustable feature does allow you to vary voltage to see if adjusting it will help you make your fuel gauge work better.
But the thing is your gauge will care more about current (amperage) than voltage. Good luck. If you understand electronics even a bit, you can use common resistors to see how varying resistance to ground will affect your gauge's reading.
Edit: the 7805 chip you found on the dryer circuit board is working fine, by the way...the "5" in the number tells you it should output 5v.
Second edit: the arm adjustment figures I gave you are for a 16 gallon tank which will normally be 11 inches down to the bottom (or the lowest point the float can drop down to). If your tank is higher (say 12 inches) and you need those numbers please let me know. A chart I prepared is attached:
