Capacitive Fuel Senders/Gauge

[chaskuss]

Originally Posted by ExtraKatana

snipped
A few questions about calibrating these capacitive gauges:
1) Do you get better resolution if you make the 9 calibration points between 0 and 15 Gallons? That's really the zone you want to know what you have.
2) Does the plane need to be level? (Vans plates)
3) Does the voltage need to be closer to an engine-running 14.xV vs. 12V?

1 I'd go from full to empty, but that's more of a personal preference.

2 Yes, as most of your flight will be in cruise.

3 Try it both ways to see if there is a difference. I suspect there won't be.

[Walt]

Originally Posted by ExtraKatana

1) Do you get better resolution if you make the 9 calibration points between 0 and 15 Gallons? That's really the zone you want to know what you have.
2) Does the plane need to be level? (Vans plates)
3) Does the voltage need to be closer to an engine-running 14.xV vs. 12V?

I have the EI CGR30 now (started with FL2 then MVP50), with Van's plates.
I calibrated at 0/5/10/15/20 with no issues.
I start with about 2 gal as '0'
And yes better to level the aircraft, voltage not a factor.

[FinnFlyer]

Originally Posted by ExtraKatana

I wrapped a small hose clamp with a stranded wire around the knurled section of the BNC and attached the other end of the wire to a paint-less tank flange screw where the fairing attaches. The erratic readings stopped, the tank reading on the EI FL2 never went to 0, and fuel was showing to drop throughout my 1 hr. flight. Thank You For Your Help!

Very pleased to hear you locate the intermittent problem!

Edit: I do have one concern if you're making that your permanent fix. It may (or may not) throw the calibration, especially near empty tank. If you see fluctuating readings near empty in the future, you'll know why. (Added ground wire slightly changing measured capacitance.)

Finn

[ExtraKatana]

Finn,
I went through the calibration process today on both tanks. had to lift the tail up to flight level, add 2 gallons at a time and record each reading. Hopefully I'm good. I had not done this since I bought the plane. Found out the semi-working side only had 5 points programmed instead of the available 9. I'm hoping to get a lot more resolution. Will see.

[ExtraKatana]

Well I spoke too soon......

The Calibration process went well and both tanks advanced the sensor number while calibrating. Both tanks showing full sitting on the ground and take-off. Looking great....
Watching left tank drop in .5Gal increments just like I programmed it. I look at right tank and "7.5GAL" when I know it has 16. this has been a problematic side.. Landed....Jiggled the BNC and all of the wires to no avail.

Guess the next step is to check capacitance directly at the tank. Don't really know what I'm doing there other than get a gauge that measures it. It still could have been a bad ground in combination with something else.

[ExtraKatana]

I thought I would give an update as so many have chimed in to try to help with the diagnosis. You always wonder where all of these efforts end up.

I was able to find a new instrument head that someone was willing to part with on eBay. After probably 15 hours of diagnosis and turning upside down and even removing the tank, the new instrument head is showing a correct reading after a one hour test flight. It’s only one hour but I never made it this far with the old instrument head. Installing the new head with the canon plug took all of about three minutes.