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  #21  
Old 06-14-2018, 09:04 PM
Flying Canuck Flying Canuck is online now
 
Join Date: Jan 2015
Location: Red Deer, Alberta, Canada
Posts: 387
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Well I tried a few more things tonight and I think I'm only left with one possibility - a bad sender. I drained the tank and used one of my seat bent hinge pins to feel around through the drain hole. Managed to find the float arm and confirm that it's moving freely. Couldn't manage to check the voltage with it moved, I was short an arm. But I know that the float isn't stuck. I put some fuel back in (10L - enough to register a notable change on the right side) and the reading from the sender never moved out of the 2.7588-2.7600 range.

I tried to remove the sender, but it's stuck there pretty solidly. With the tank/wing mounted there aren't many places where I can pry on that plate. Any ideas on how I can get that out without removing the tank?
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  #22  
Old 06-15-2018, 08:06 AM
219PB 219PB is offline
 
Join Date: Aug 2014
Location: Victoria, Tx
Posts: 421
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What about making a bracket to hold a piece of thin safety wire taught, then working it behind the plate? I Prosealed mine on with a 1/16" gap and that was how I would plan to remove if and whenever I needed to.
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  #23  
Old 06-16-2018, 01:11 PM
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f14av8r f14av8r is offline
 
Join Date: Apr 2012
Location: Tampa (Wimauma actually)
Posts: 421
Default Fuel Sensors Suck

It think we accept a level of performance that is simply out of touch with modern technology when it comes to fuel sensors. I hate mine! I mean, really! Van's and the rest of the fuel sensor world can't come up with a fuel sensor system that will accurately indicate my fuel level from full to empty? It makes me angry.

I found this thread while researching a problem with my right fuel tank float sensor. It has decided, after 105 hours of operation, to set the fuel level at 1.8 gallons and never move again. I'll figure that out, but as I troubleshoot, I sure would like to improve the situation such that I can know the fuel level accurately at all times. Is that really too much to ask?
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Randy King
Tampa (Wimauma), Florida
RV-4 N212CS (sold)
RV-8 N184RK (flying)
Flying an A320 to pay the bills
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  #24  
Old 06-16-2018, 01:44 PM
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swisseagle swisseagle is offline
 
Join Date: Feb 2005
Location: 20km outside of Zurich, Switzerland
Posts: 468
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Ground your fuel-sender plate!

Mine was ok, when weather was wet or high humidity. When cold and dry, it showed different levels down to zero.

Then I grounded the fuel-sender-plate and voila: all is fine!

It is old technologie, the floating fuel sender. But if you calibrate them with modern EFIS/EM's, then the become really accurate. Anyway, you should not count to the last liter!
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RV-7A, TMX-IO-320, FM-150, Sensenich FP
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Last edited by swisseagle : 06-16-2018 at 01:47 PM. Reason: prolem with picture and spelling ;-)
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  #25  
Old 06-16-2018, 01:59 PM
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f14av8r f14av8r is offline
 
Join Date: Apr 2012
Location: Tampa (Wimauma actually)
Posts: 421
Default Yes, but

Yes, I may be able to get my sensor working but, even at it's best, it won't indicate the level accurately over about 16 gallons in a 21 gallon tank. That, I think, is unacceptable. Perhaps we've identified a market for a new product - an accurate fuel level sensor throughout the fuel range!
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Randy King
Tampa (Wimauma), Florida
RV-4 N212CS (sold)
RV-8 N184RK (flying)
Flying an A320 to pay the bills
Exempt and gladly donating anyway - Current through March 2021
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  #26  
Old 06-16-2018, 02:33 PM
Flying Canuck Flying Canuck is online now
 
Join Date: Jan 2015
Location: Red Deer, Alberta, Canada
Posts: 387
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As long as the wings (and the fuel tanks) have dihedral, I don't think there's a float based mechanical sensor that's ever going to get you to both the top and the bottom of the tank. The first ~4 gallons don't reach to outboard end and the last few gallons sit away from the inboard end. When on the inboard end, the float is at it's highest possible position well before the tank is full.

I tried adding a ground to my non-working sender and it didn't help. I'm going to have to remove it (the cheese slicer trick with safety wire sounds promising). I think I'm going to leave it alone for the time being and go ahead with the final inspection with this outstanding. I do have a few other sensor related issues though (oil pressure, CHT #4 both work fine unless the engine is running) and my alternator isn't charging - so I may be having to move the inspection out anyways.
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  #27  
Old 06-16-2018, 03:16 PM
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f14av8r f14av8r is offline
 
Join Date: Apr 2012
Location: Tampa (Wimauma actually)
Posts: 421
Default Fuel Senders

I understand the mechanical limitations of a float based sender. I'm just surprised that nobody has come up with a full range solution to the problem!
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Randy King
Tampa (Wimauma), Florida
RV-4 N212CS (sold)
RV-8 N184RK (flying)
Flying an A320 to pay the bills
Exempt and gladly donating anyway - Current through March 2021
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  #28  
Old 06-16-2018, 05:15 PM
cajunwings cajunwings is offline
 
Join Date: Jun 2007
Location: new iberia la
Posts: 768
Default Fuel gauging.

Mooney’s have a 2nd additional float type fuel sender on the outboard tank rib that must be in series with the inboard sender. Numerous times after fuel tank work I’ve filled them up a few gallons at a time and indicated quantity would match the truck within a 1-2 gal empty to full. Wondering how much sense it makes to add that cost, weight, complexity, addition failure modes to a small plane that likley has a totalizator on board. But hey, this is the best part of E/AB. All we need is a drill and a little common sense to do almost whatever we want. Gotta love this country and our aviation rules. Personally I’m ok with the gauges not showing the upper 1/3 of the quantity if they work on the bottom 2/3. Small plane gauging systems have never been great and it’s wise to treat what the gauge shows as only a opinion on what you already know.

Don Broussard
RV9 Rebuild in Progress
57 Pacer

Last edited by cajunwings : 06-16-2018 at 05:31 PM.
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  #29  
Old 06-16-2018, 06:36 PM
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Larco Larco is offline
 
Join Date: Mar 2005
Location: DVT Phoenix
Posts: 1,187
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Quote:
Originally Posted by f14av8r View Post
I understand the mechanical limitations of a float based sender. I'm just surprised that nobody has come up with a full range solution to the problem!
It is probably because no-one wants to spend 10s of thousands of dollars designing something unnecessary and never recoup their investment. This might be an opportunity for you to come with something. :-)
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  #30  
Old 06-16-2018, 07:00 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 1,120
Default Easy peasey

Actually, I think with modern electronics it is easy to make the fuel senders read from full to empty. Just add one at tip of the tank and wire them in series. The tip rib sender would need to be tweaked so it is not referenced to structure ground, but this is easy to do during installation. It might be possible to have the sensors in parrell too, so that both are reference to chassis ground; i am not there yet in my build so dont know the details of the G3x fuel level calibration ranges.

I was talked out of adding a sender in the tank tip rib; now i wish I would have done it during tank build.oh well.
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

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