| flatheadfan | -- 05-22-2012 @ 1:31 AM |
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I have a '36 Ford with an electrical gas tank indicator. I have had this for years without any problems and then something weird started occurring. When you turn on the ignition the gauge would read accurately and then the indicator would start dropping back to empty. If you turned off the ignition and waited 5 minutes the same thing would occur again. I pulled the dash unit and bench tested it and it read normally. I reinstalled it and hooked a separate wire from the dash unit to another sender and the dash unit read normally. Conclusion- it must be the sender that is giving me grief. Unfortunately, to get to the sender I must pull the gas tank. I have a rumble conversion in the coupe which prevents any sort of access to the sender from the top. So, everything must be handled from below. I pulled the tank removed the sender bench tested it and it work just fine. Just to be safe I replaced the sender with another that tested good. To insure a good ground I made a separate ground wire from the sender to the car frame. I put everything back together and everything read normal. Now the same problem is starting all over again. I re-checked the dash unit, strung a new wire back to the tank, Re-checked everything with another sender and everything works like it should. I am at the point of pulling the gas tank again and re-checking the tank sender but I don't think I will find anything wrong. I'm stumped! I am open for suggestions. Thanks. Tom
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| Don Rogers | -- 05-22-2012 @ 3:58 AM |
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Have you tried isolating the fuel gauge from the oil gauge by removing the metal strap at the top of the duel gauges? Perhaps something is going on with the oil gauge circuit that is affecting the fuel gauge. Just an idea!!
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| TomO | -- 05-22-2012 @ 6:54 AM |
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The gauge reads empty when the current in the circuit is not enough to move the needle towards full. As Don said it could be the electrical supply connection to the fuel gauge. The contacts in the tank sending unit may be dirty or you have a loose connection between the sending unit and the gauge. Recheck your ground connection by connecting a jumper between the gas tank and the ground strap on the battery. If you have a radio condenser connected to the sending unit or gauge, it could also be failing. Tom This message was edited by TomO on 5-22-12 @ 6:55 AM
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| flatheadfan | -- 05-22-2012 @ 7:39 AM |
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Guys- I think there may be something to what you guys are suggesting. I put everything back together this morning and turned on the ignition. The gas gauge didn't move. I started the engine and then the oil pressure came to life. At the exact same time the fuel gauge woke-up and read "normal." I took the car for a short run and watched the two gauges. The fuel gauge remained "normal" but the oil pressure was indicating 50+ pounds of pressure at 35 mph, which is not normal. As it stands now I am going to drive the car for a few days watching how things go. If things get weird again the oil gauge and its' sender are getting changed. Thanks Tom
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| supereal | -- 05-22-2012 @ 9:47 AM |
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Be sure to check your system voltage. If it is erratic or exceeds 7.5 volts, the charging system or battery may be at fault.
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| TomO | -- 05-23-2012 @ 7:20 AM |
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You definitively have a problem with the combined gauge. It could be that your oil pressure sending unit is not grounded properly (someone used teflon tape on the threads or rust has compromised the ground) or the voltage connection is loose or corroded. Tom
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