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fuel sender wires

Scott Will

Well Known Member
This may seem like a dumb question... but I want to run the wires to the wing root now.

With the Warner traditional fuel senders (float type), what size and how many wires go to the unit? At work now so I dont have the install instructions now. Just planning tonights work.

Thanks much,
Scott
 
Only one wire goes to the sender (it is grounded locally) and since the current is very small, any size wire will do. Anything smaller than 20GA gets to be a little hard to work with, so I'd use 20. Also, even though the sender is grounded to the tank by the attaching screws, it might be worthwhile to have a seperate ground wire from one of the screws to the ground on the sender. I did this and my senders work like a charm. I'm not certain that they helped any, but couldn hurt.
 
sprucemoose said:
.....to have a seperate ground wire from one of the screws to the ground on the sender.
Jeff's suggestion works as long as there's good contact between the screw and the plate nut. There should be, but there's also Proseal in there as well. If you run the wire, it might be a good idea to go from under the screw (against the plate) to the spar or rib. Probably doesn't really matter much either way to be honest. It's always a good idea to use a continuity tester just to make sure you have a good ground plane.

I think the ground wire is a very good idea. Some of the problems that others have encountered with the fuel indicators has been tied to poor or intermittent grounding of the sender.
 
I checked mine with an ohm meter just the other day.

I have just finished my last tank, and I was wondering the same thing as Scott. I'm actually a pretty good electrician but was just wondering what other people were doing. I would have installed a ring terminal for a ground wire under one of the sender screws if I had thought about it. :confused:

With an ohm meter I checked the sender flange to to the rest of the tank and got zero resistance. I think those screw heads make pretty good metal to metal contact even with the proseal on there. I didn't use the gasket, so the screws should stay as tight as they are now.

So, I don't plan to run a dedicated ground to the sender at this point.

Mark
 
I'm having fuel guage problems too. I've got an RV9A and I'm the third owner, not a builder. My gauge is through a g3x touch. The gauges do not work right. Sometimes they move and sometimes they don't and they are never accurate. I tried grounding the sender to the airframe, no change either side. I tried disconnecting the wire to the sender and there was no change in guages at all on either side. They are float type senders - I think the "normal" one for the 9. Is this possibly a G3X setup issue? Is seems crazy that neither Guage changed when I disconnected the wires or grounded them to the airframe using a piece of wire.
 
Jeff's suggestion works as long as there's good contact between the screw and the plate nut. There should be, but there's also Proseal in there as well. If you run the wire, it might be a good idea to go from under the screw (against the plate) to the spar or rib. Probably doesn't really matter much either way to be honest. It's always a good idea to use a continuity tester just to make sure you have a good ground plane.

I think the ground wire is a very good idea. Some of the problems that others have encountered with the fuel indicators has been tied to poor or intermittent grounding of the sender.

Good electrical contact between the screw and the nutplate is highly unlikely to be a problem with the amount of friction that’s involved in installing the screw because of the locking feature on the nutplate. The electrical continuity problem is usually from sealant between the screw and the cover plate and or the screw and the sender flange. Some of the construction manuals now call for an external tooth lockwasher under at least one screw on the cover and the sender flange. This has seemed to solve lack of continuity issues between the screw and the cover or sender.
 
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