Fuel Senders

[jensscott]

I have a restive sender in the center tank and one in the right aft tank (ac520-39 N411VV). I can't keep them working reliably. Any recommendation of a replacement sender and gauge?

Jens

[Dhavillandpilot]

I found the fuel indicating system in the commander (mines a 685) are unreliable. And worst still in
One other types you cannot even look into the tanks.

I installed a JPI fuel monitoring system as the primary indicator system.

Once you get the K factor right it is extremely reliable.

We do about 400 hours a year so at each 100 hourly we run the fuel down, drain it then replace and re set the data.

Over the last 800 hours the unit has been out some 15 litres we 100 hours. We put this down to direct priming for starting

[Adam Frisch]

Yes, with all my Commanders the fuel sensors and gauging has always been bad. What I did in the 520 is drained it and calibrated the gauge - it was empty when it still showed 50 gals or something! Also never showed full properly, just stayed below there for a really long time until the levels dropped. Unless you're willing to exchange the sensors for newer solid state ones and get a 337, they're just going to stay iffy.

In the turbine it's the same thing. Meters get stuck, not showing right amount etc - it's all over the shop. Thankfully there the Foxboro fuel totalizer is very accurate, so as long as you know how much you have in tanks initially, you can plan very accurately.

[donv]

That's all true until you get to the Jetprops. They have very accurate fuel gauging.

[Rich]

Agreed - on the work 695, we record uplifts, gauge readings, and the burn from the totaliser and everything always agrees to within about 50lbs. Sounds like the older models are just pretty similar to most other light singles/twins when it comes to fuel gauge reliability!

[donv]

690s are notorious for indicating more or less full, staying that way, and then all of a sudden dropping to 1200 pounds and staying there for a while. I've never trusted them enough to run them too low and see how they behave below, say, 500 pounds.