EjT Posted July 15, 2020 Report Share Posted July 15, 2020 Have an intermittent fuel gauge. 3 wire on gauge, two wire to sending unit. I assume the two wires to the sending units are not hot. So how exactly does this gauge work? There\s the hot from the ignition but where is the ground? Is the second s/u wire grounded at the gauge? Thanks for any help in troubleshooting this. Can't seem to find any info on this configuration. Quote Link to comment Share on other sites More sharing options...
sidevalvepete Posted July 15, 2020 Report Share Posted July 15, 2020 My car is 38 D9 Dodge so may not necessarily apply to you so advise you to get a wiring diagram from maybe this site or get a workshop manual from ebay etc. Anyway my wiring diagram may help so have included picture. Only the two wires from the gauge. One to ignition switch and the other to the sender unit. System will earth itself. Hope this helps. Quote Link to comment Share on other sites More sharing options...
EjT Posted July 15, 2020 Author Report Share Posted July 15, 2020 I have wiring diagram. Your 38 has one wire to s/u and grounds thru tank....makes sense. 39-42 have two wires from s/u. Wires 34 and 35 running from "HH" s/u to "T" gauge. So where does the ground come from? I don't have access to this car right now so trying to understand the concept to help when I'm able to work on it. Quote Link to comment Share on other sites More sharing options...
glasspacks Posted July 23, 2020 Report Share Posted July 23, 2020 Autolite and King Sealy produced a lot of these gauges. Autolite produced magnet coil gauges where as King Sealy produced thermal wire gauges. The two wire gauges ground at the tank sender as far as I know. Hope that helps Bob. Quote Link to comment Share on other sites More sharing options...
50mech Posted July 28, 2020 Report Share Posted July 28, 2020 Quote Link to comment Share on other sites More sharing options...
harveyspoint Posted August 2, 2020 Report Share Posted August 2, 2020 EJT....Perhaps this will help...Maybe not...Bought a '47 P15 Coupe about 5 years ago....The previous owner said the fuel gage sometimes worked, sometimes didn't... I checked til I was blue in the face...Finally, I took the cork float off and compared it with my '48 float...The '47 float weighed twice as much as the '48...The cork float is dipped in shellac at manufacture to seal it...Alcohol is a solvent for shellac....Methanol is alcohol...After the alcohol removes the shellac, the cork absorbs gas, making it heavy until it won't float...I bought 2 floats from Snyders Antique Auto Parts....Ford Model A...for about $2.50 each, I don't remember, and put them on in place of the old cork float... They were guaranteed to not absorb gas....this took care of all my gas gage problems....it wouldn't hurt to try.. I have a '52 Plymouth Overdrive on my '47 Coupe...Makes it run down the road like a modern car....I ran my '48 for 25000 miles with this setup and couldn't have been happier...Chuck.... Quote Link to comment Share on other sites More sharing options...
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