Fuel sender question

[Wingover]

Trying to figure out if my issue is the gauge or sender.   The gauge shows less than full when I fill the tank.  Right now I have about 8 Gal and when I pull the outboard float up it doesn't affect the gauge. 

Where do you start the diagnostic process? 

[christaylor302]

The stock fuel senders are resistive. So you should be able to connect a Ohm meter and watch the value while swinging the float. There should be a smooth change in value from top to bottom. I don’t know the top and bottom of the range. But it should be a smooth sweep.


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[Wingover]

19 minutes ago, christaylor302 said:

The stock fuel senders are resistive. So you should be able to connect a Ohm meter and watch the value while swinging the float. There should be a smooth change in value from top to bottom. I don’t know the top and bottom of the range. But it should be a smooth sweep.


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Do I need to disconnect the wire from it or it doesn't matter?

[Ragsf15e]

Also, you have at least two senders in each tank, so pulling up one might not make a change if the other is the problem.

[Wingover]

42 minutes ago, Ragsf15e said:

Also, you have at least two senders in each tank, so pulling up one might not make a change if the other is the problem.

You are right.  They are connected in a series so I would think it would make a difference.

[christaylor302]

Do I need to disconnect the wire from it or it doesn't matter?

Yes, you’ll need to disconnect the lead to the gauge so you only measure the resistance through the senders.


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[Pinecone]

Power goes from gauge to inboard sender to outboard sender to ground.

You need to check both senders and make sure there is not a short to ground.

Each sender has a resistance range of 0 - 30 ohm (empty to full range).

[Yourpilotincommand]

Is there any adjustment on the back of the gauge? I have a similar problem.

[DCarlton]

7 hours ago, Yourpilotincommand said:

Is there any adjustment on the back of the gauge? I have a similar problem.

Air Parts of Lockhaven can overhaul and calibrate the OEM gages.  I’ve had mine serviced.  

[LANCECASPER]

On 1/9/2025 at 10:04 AM, Wingover said:

Trying to figure out if my issue is the gauge or sender.   The gauge shows less than full when I fill the tank.  Right now I have about 8 Gal and when I pull the outboard float up it doesn't affect the gauge. 

Where do you start the diagnostic process? 

If this is the first time it's happened sometimes the sender gets "stuck" and a good bump on the outside near the sender will take care of it. If it's been this way awhile then my next guess would be a bad sender.