calibration of mechanical fuel gauge?

[philipneeper]

Hello mooneyspacers,

Im fixing to do a reseal on my fuel tanks. I was curious if there is a way that i can calibrate my mechanical fuel gauges that are located next to my filler caps? Currently they are off by a good bit. When i have 15 gal in the tank the gauge depicts close to 20 gal. Anyway i can fix that or am i SOL? Thanks

[thinwing]

Hi Philip...a more important issue is how the read at near empty and near full...ie what do they read at 5 gal ??

[philipneeper]

when full they are way above the 25 gal indicator. when they are at 5 gal it shows empty. when at 15 gal its bewteen its dead center between 10-15... and the higher it goes its the same... seems to be reading 3-5 gal more than actually in tank.

[jetdriven]

bend the wire arm to the float

[philipneeper]

I havent torn into the tanks yet. I wanted feed bck first. Heaven forbid i break those things. If i put 10 gal in there and calibrate it to that do you think it will be closer to accurate for the others?

[N201MKTurbo]

Bending the arm to make it shorter or longer will change the scale factor. Bending the arm to make it higher or lower will change the offset. I would suggest finding out how much fuel is in the tank when the float just lifts off the bottom of the tank and how much fuel is in the tank when the float is pinned to the top.

When the tank is apart and empty adjust the float until it reads the correct readings when against the top and bottom of the tank.

[Piloto]

Bending the float wires is easier said than done, specially when there is fuel in the tanks. Most likely your problem is due to fuel deposits on the sender rheostat or connections. Next time the tanks are empty remove the inboard and outboard senders and have them submerged in MEK to clean all residue. To remove the inboard sender you will need to take the side panels off for access. When reinstalling them apply PRC-1422-B2 on the ring.

José

[philipneeper]

  On 12/20/2012 at 3:00 PM, Piloto said:

Bending the float wires is easier said than done, specially when there is fuel in the tanks. Most likely your problem is due to fuel deposits on the sender rheostat or connections. Next time the tanks are empty remove the inboard and outboard senders and have them submerged in MEK to clean all residue. To remove the inboard sender you will need to take the side panels off for access. When reinstalling them apply PRC-1422-B2 on the ring.

José

i only have the inboard sensors and i know they need cleaned. But my question was for the mechaincal sight gauge Piloto. worse case scenario, when i put fuel in it i can mark my own lines.

[Piloto]

  On 12/20/2012 at 3:45 PM, philipneeper said:

i only have the inboard sensors and i know they need cleaned. But my question was for the mechaincal sight gauge Piloto. worse case scenario, when i put fuel in it i can mark my own lines.

The wing sight gauges are calibrated only for the 32 gals tanks for the M20J. There was no sight gauges for the 26 gal tanks in the M20C. To make them read accurately you will need to bend them up or pry out the dial and rotate it.

José

[philipneeper]

I have a C model and it has 26 gal tanks and i do have visual gauges next to gas caps

[WardHolbrook]

Here is something, that in the near future, may really help in dealing with grossly inaccurate fuel gauges. Hopefully they'll be available for other aircraft besides Cirri.

http://www.aopa.org/aircraft/articles/2012/121022digital-fuel-sender-now-certified.html#.UIa_AiYpz0B.blogger

[Lionudakis]

I just installed one of these and found it to work well, and surprisingly accurate compared to a separate fuel flow unit, even with old sensors in a cessna. Unless the floats are just plain not working, intermittent or damaged. Regardless of float readings, the unit programs itself to the sensor output. After install you program it by adding 2 gallons at a time, from empty to full, so it knows what empty and full is, and everything in between. 

 

http://www.aircraftspruce.com/catalog/inpages/aerofl202.php?clickkey=22245