I agree with your diagnosis. It's gotta be reversed polarity...of the sense and gnd. Fundamentally the fuel gages are just voltage meters. They respond proportionally to the voltage drop across the variable resistance in the sender. I would disconnect the leads and use an ohm meter to measure and validate the resistance of the senders. Switching the polarity of the sense and gnd monetarily probably won't break anything. Before doing so validate that your wiring looks like the attached picture.
Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD I'm sharing an electrical problem right now in the hope that someone here on this list has had a similar problem and solved it... Over the winter I added an auxiliary 19-gallon diesel tank under the nav station seat. I decided to buy 2 new fuel gauges, one for the new auxiliary fuel tank and the other a replacement of a 30-year old fuel gauge for the primary diesel tank. Both (Sierra-brand) gauges are mounted in the cockpit coaming on the port side with nice labels. My 30-year old fuel gauge was working fine but it was mounted in the engine panel and didn't match the color and style of the other gauges--this is primarily why I replaced it. I made a nice teak pad (located inside near the gauges) on which I mounted terminals and bus bars to properly organize the new wiring for all the gauges. I completely wired up the new fuel gauges in accordance with the instructions. (I rewired so that I could get rid of a lot of old un-tinned wire.) When I turned on the ignition to check the gauges function, the needles on both gauges moved to below empty. This usually means an open circuit on the sender side. I've thoroughly checked all the wiring and the gauges and I can't find any problem with the wiring or the gauges. I've checked the resistance across the sender on the new auxiliary tank and it measures 230 ohms--since that tank is empty, the resistance sounds about right. The primary tank's sender is more difficult to access, so I couldn't measure it. Last night, I checked the tank's grounding by running some extra temporary ground wires--no difference. What's weird is that the problem is affecting both gauges the same way. Any ideas as to what the problem may be? Its almost like the polarity of the power input is reversed, but it isn't. Bob Bob Boyer S/V Rainy Days / Annapolis MD 1983 C&C Landfall 38 - Hull #230 email: dainyr...@icloud.com blog: dainyrays.blogspot.com "There is nothing--absolutely nothing--half so much worth doing as simply messing about in boats." --Kenneth Grahame _______________________________________________ Email address: CnC-List@cnc-list.com To change your list preferences, including unsubscribing -- go to the bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com
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