Troubleshooting Fuel Indication Issue

[Slick Nick]

1991 J model MSE. When I’m down around half tanks, in turbulence, my right side gauge will dip down to zero and come back to half, seemingly in response to the bumps. When it does this, my “R LOW FUEL” annunciatior also lights. It sort of flickers in conjunction with the gauge. I have confirmed that there is fuel in the tank. 

Trying to determine if this is an issue with the inboard sensor on the right wing, or perhaps wiring somewhere along the line before I send it into the shop for diagnosis. Any hints on where to start?

[Fix]

Most likley one of the fuel senders in the fuel tank.
It's quite easy to test them on ground.

[JimK]

I recently had a similar problem with my LH fuel guage.  I too suspected the inboard sender and spent a lot of wasted time troubleshooting it to no avail.  The inbd and outbid senders on a specific tank are wired in series so either sender malfunctioning will screw up the indication for that tank.  I recommend you remove the outbd one first because it is so much easier to access and you don’t have to drain near as much a gas to do it.  Bench test it with an ohm meter.  It should smoothly register changes from zero to 30 ohms as you move the float from one end of the travel to the other.  If there are any dead spots, jumps or hesitations in the readings, send it off to Air Parts of Lock Haven.  For $220 they will overhaul it for you and, for another $7 they will include a new gasket (much cheaper than Laser).  If it’s not the outbd sender you will have to remove the inbd one first because and do he same test.