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  #1  
Old 01-02-2018, 02:29 PM
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MacPara MacPara is offline
 
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Location: Tucson, AZ
Posts: 461
Default Fuel Level Sensor Issue

I've searched the forum but could not find this being reported before, so maybe this is something no one else has seen yet.

While completing my annual I noticed vanishing fuel in my tank - at least according to the Dynon Skyview indication. Every time I came out to the hangar to complete another piece of the annual inspection the fuel level showed a bit lower. The Moeller gauge had not moved nor was the sight gauge (yeah, mine is still not leaking, knocking on wood) showing any lost fuel, so I knew this indicated a sensor issue.
First I thought this was another case of a sunk float, one that wasn't related to Bing this time, but my interpretation changed when I noticed the fuel level coming back up during some post-annual prop balancing work.
I decided to ignore the false indication, given that I have two additional (and working) sources to indicate fuel level and go flying.
On take-off the fuel level indicated 0 gallons and during a 30 minute flight the level came back up to 12 gallons only to fall back off to 9 at landing when the real fuel level was always more than 16 gallons.
Has anybody fought such a gremlin before?
My current theory is that this is unlikely a float issue but could possibly be related to a bad ground. The later would be odd as I did install a dedicated ground wire to the tank when I built her. However, this wire might be broken.
I'll investigate further and report what I find but was hoping to get some input from guys that might have seen this before and fixed it....
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  #2  
Old 01-02-2018, 03:29 PM
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Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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Check for bad ground wire to fuel tank.
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Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 366

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  #3  
Old 01-02-2018, 04:09 PM
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DaleB DaleB is offline
 
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Location: Omaha, NE (KMLE)
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Seconded. I had my tank out to install all of the SBs, and repainted it with epoxy primer while it was out. After re-installing I had erratic and intermittent fuel level indications from the float gauge. I ended up having to run a dedicated ground wire to one of the float gauge screws, it's been fine since then.
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  #4  
Old 01-02-2018, 04:55 PM
Mich48041 Mich48041 is offline
 
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Location: Riley TWP MI
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Grounding the tank might not be good enough because tank sealant is an insulator. Take Dale's advice and ground the level sensor mounting plate.
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  #5  
Old 01-02-2018, 04:58 PM
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Piper J3 Piper J3 is offline
 
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Also, might be too warm where you're located...
-
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Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 366

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #6  
Old 01-02-2018, 06:17 PM
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Phantom30 Phantom30 is offline
 
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Quote:
Originally Posted by Piper J3 View Post
Also, might be too warm where you're located...
-
For thoughs of you flying in the”cold”....the Bender Baffle is the best mod i’ve Done. Even flying down in AZ this Winter...several friends have really liked the warm air my heater kicks out in the early AM.
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  #7  
Old 01-02-2018, 06:24 PM
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Piper J3 Piper J3 is offline
 
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Cold in the early AM in AZ

Pleeeeez...
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Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 366

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #8  
Old 01-02-2018, 06:41 PM
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MacPara MacPara is offline
 
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Quote:
Originally Posted by Piper J3 View Post
Cold in the early AM in AZ

Pleeeeez...
Well, yeah! It's like freezing 45F in the mornings down here. It's killin' me!
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RV-12: #120374, ELSA, N128TL flying since Nov 28, 2013 (Phase 1 completed 1/26/14)
SkyView, Light Package, ADSB
http://torstensrv-12.blogspot.com/
APRS Track
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  #9  
Old 01-02-2018, 06:42 PM
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MacPara MacPara is offline
 
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Quote:
Originally Posted by Mich48041 View Post
Grounding the tank might not be good enough because tank sealant is an insulator. Take Dale's advice and ground the level sensor mounting plate.
Yeah, that's what I've done. Ran a ground wire to the plate the sensor is mounted on. I will check the wire. I am pretty sure this has to be it.
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RV-12: #120374, ELSA, N128TL flying since Nov 28, 2013 (Phase 1 completed 1/26/14)
SkyView, Light Package, ADSB
http://torstensrv-12.blogspot.com/
APRS Track
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  #10  
Old 01-02-2018, 07:22 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
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A guy on our field got an SLSA with wandering fuel level indication. He found a bracket in the avionics bay that was used for ground, but the contact surface had been primed. After removing the primer the problem went away
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