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cycling has-been
Join Date: Sep 2004
Location: Jersey Shore
Posts: 7,241
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Erratic gas gauge needle - 77 930
If I fill the car up and drive for what feels like 3/4 tank, the needle stays at 1/2 for about a hundred miles, then takes a huge dive to empty - as in reserve light. (Very disconcerting!)
Is there such a thing as cavitation in the sending unit? I have not had the sender out on this car. (yet) Thanks. Bill K
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73 911T MFI, 76 912E, 77 Turbo Carrera |
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08-09-2013, 03:20 AM
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Been here a while
Join Date: Apr 2004
Location: East coast, west coast, typ. 35,000 ft
Posts: 2,442
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I've had this exact problem with my 79 sc, swapped the sender, and it remained exactly the same, turned out it was a faulty gauge.
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looking for 1972 911t motor XR584, S/N 6121622 |
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08-09-2013, 04:20 AM
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Registered
Join Date: Apr 2010
Location: New Orleans, LA
Posts: 1,493
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take out and clean the tracks the float rides on.
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1982 911SC, Mocal oil cooler, Bilsteins, Carrera tensioners, backdated heat, factory short shift, Seine gate shift, turbo tie rods, pop off. 2005 Mercedes-Benz C230 kompressor sport 6-speed (daily driver) |
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08-09-2013, 04:20 AM
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cycling has-been
Join Date: Sep 2004
Location: Jersey Shore
Posts: 7,241
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thanks guys.
I think I'll pull the sender to check it out, and pending the outcome from that, swap the gauge back to the original. I put in another (used) gauge when the original started to fog up in high humidity about 6 years ago. Bill K
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73 911T MFI, 76 912E, 77 Turbo Carrera |
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08-09-2013, 05:34 AM
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Registered
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Fogging up in the gauges seems to be as normal as smoke inside Lucas wiring :-)
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The "collection" 1983 911 SC Targa (1 of 1430 imported) 1994 MB E320 Coupe (1 of 825 imported) 1992 MB 190E 2.6 2004 Volvo V70 2.5 Turbo (1 of a bazillion imported) 
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08-09-2013, 05:42 AM
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cycling has-been
Join Date: Sep 2004
Location: Jersey Shore
Posts: 7,241
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Quote:
The float rides up and down inside a brass tube that is sealed and bolted at the end. I removed the securing screw that holds the end of the centering float rod, but the plastic has been sitting in a bath of Sunoco 93 for the last 37+ years and I did not want to break it into tiny little pieces. Are we talking about the same sending unit? As long as I had the sending unit out, and float was moving freely, I shot it with a healthy dose of Marvel Mystery Oil to lube the inside of the tube. Bill K
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73 911T MFI, 76 912E, 77 Turbo Carrera |
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08-12-2013, 04:29 AM
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Been here a while
Join Date: Apr 2004
Location: East coast, west coast, typ. 35,000 ft
Posts: 2,442
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yes, after removing the nut at the base of the sender, you can slide the cover off, but I still feel it is more like the gauge that is at fault.
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looking for 1972 911t motor XR584, S/N 6121622 |
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08-12-2013, 05:56 AM
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cycling has-been
Join Date: Sep 2004
Location: Jersey Shore
Posts: 7,241
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I did swap the gauge also, but I have to burn 3/4 tank of gas to see if that fixes the problem.
Bill K
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73 911T MFI, 76 912E, 77 Turbo Carrera |
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08-12-2013, 06:16 AM
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Registered
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My erratic gauge persisted after cleaning the sender and then replacing it. It points accurately when I mess with the ground tab on the gauge. Cleaning the connectors didn't help so I think it is the internal connection of the ground. If you narrow it down to your sender I have a very serviceable used sender in factory packaging from my replacement.
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75 911S Targa - Mine from 2001 until sold to Germany buyer 10/2016 <ALL DIY> Brakes/Wheels '01, Body/paint/restoration 7/04, Suspension 3/07 Engine rebuild - done 7/08 - added 28 tube cooler and SSIs - running strong. Ducktail painted. 2021 MachE, 2012 Outback, 2019 Crosstrek, 2018 Impreza wagon |
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08-12-2013, 08:48 AM
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Targa
