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Fuel Calibration G3X Touch

BGS

Well Known Member
Was going to calibrate my fuel tanks today on my RV10. In the Garmin I set up the calibration page to Fuel 1, Resistance sender, starting voltage displayed .005 volts. Added fuel and nothing changed. Ended up putting in 15 gallons and no change on the G3X.
So was thinking my floats were stuck so I checked the ohms on the sender itself and it looked to be reading just fine. As I drained fuel, the ohm reading kept changing so now I knew the floats were working.
Still got the same reading of .005 volts on the G3X
Then thinking this may be a ground issue, I connected the ohm meter in line between the sender and the wire going to the Garmin. I was getting the correct readings so thinking the ground is ok on the sender to tank and that hte wire is hooked into the Garmin.
I then thought maybe the wires in the GEA may have been put into the wrong pins so checked the aux tank 3 and 4 and they also read the same amount.
So, out of ideas on where to go from here. Any ideas out there.

Thanks for any help.
Brian
 
Will have to give the grounding wire a try. Was thinking it would not be needed since I when I check the voltage in line between the sender and the gea the readings are good on both tanks. However I understand these are pretty sensitive to ground so will give it a try

Thanks
 
So went and added a ground wire as mentioned from the sender with a star screw under the head and attached other end to the frame. No luck with it working. So added another ground to another screw and wired the ground directly to the ground bus. Still nothing.
Not sure where to go from here???
 
So went and added a ground wire as mentioned from the sender with a star screw under the head and attached other end to the frame. No luck with it working. So added another ground to another screw and wired the ground directly to the ground bus. Still nothing.
Not sure where to go from here???

Hello Brian,

Lots of standard things we run through with you when you contact us by phone/email. We don't know anything about where you are starting from here.

Surprising how many people start troubleshooting without loading the latest software to get everything in the system up to date and at the same level. The software that is loaded into the various devices when they are manufactured may not even be fully compatible at the system level.

It is best to contact us by phone or email shown below. We will want to start by verifying the software is up to date and the fuel probe is properly configured.

99% of the problems are wiring related, so don't hesitate to re-verify that the signal from the left fuel probe is going into pin 6 on P244. It sounds like you got nothing for an input signal, so wiring and configuration is certainly suspect.

Not to worry. Probably something simple. Many times we hear back that everything is working fine after the software was brought up to date.

Thanks,
Steve
 
Hello Steve. I am going to pull ththe her was going into the gea again to do but to see if it is a pin issue. Did it once but going to try again and this time ohm it to make sure.
The software was all updated last week so should be good there.
Have the G3Xpert setup for resistive senders. Using the factory supplies senders.
Will also give you a call to go over this if issue persists.
Thanks
 
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I had a similar problem. Checked the reactance at the tank looked good. After some other trouble shooting I realized I had used sheilded wire per Garmin. I had failed was connected to the shielding not the wire. I know I looked dumb and probably shouldn't be posting my error but hope this could help
 
Hello Steve. I am going to pull ththe her was going into the gea again to do but to see if it is a pin issue. Did it once but going to try again and this time ohm it to make sure.
The software was all updated last week so should be good there.
Have the G3Xpert setup for resistive senders. Using the factory supplies senders.
Will also give you a call to go over this if issue persists.
Thanks

Hi Brian,

Sounds good. A little more information.

When you configure the fuel quantity input for a resistive fuel quantity sensor, the GEA 24 enables an internal pull-up resistor that applies a small signal to the potentiometer wiper inside the float type fuel probe.

As the resistance varies with fuel quantity, the voltage drop across the variable resistance changes, which is what is measured by the GEA 24.

Since you report that it is not seeing a changing voltage, something is probably wrong with the installation.

Thanks,
Steve
 
This morning I removed the GEA harness to double check the wires. Fuel tank 1/L is wire is going to Pin #6, and 2/R is going to pin #9. While apart I did an ohm check to make sure those were the actual wires and it checked out.
Double checked the software update and everything is up to date. Version 5.9 is installed and all LRU's should be the latest software as well.
Both sender setups in the G3X are set to resistance. Ground wires have been verified, one stud on the sender going to a main fuselage bolt and another stud going directly to the ground bus.
Checked the sender again with a meter and as fuel is removed, the voltage increases. When putting the meter between the sender and the GEA, I get the same measurement as if I was going from Sender to ground. This makes me think the ground is good.
Still no luck on getting any reading through the EFIS.
 
This morning I removed the GEA harness to double check the wires. Fuel tank 1/L is wire is going to Pin #6, and 2/R is going to pin #9. While apart I did an ohm check to make sure those were the actual wires and it checked out.
Good, as long as these pins are on P244. There are 4 connectors on the GEA 24.

Double checked the software update and everything is up to date. Version 5.9 is installed and all LRU's should be the latest software as well.

Is it best to not assume that the devices are using the correct software without seeing it on the Device Information page. The GEA 24 should be using V3.10.


Both sender setups in the G3X are set to resistance. Ground wires have been verified, one stud on the sender going to a main fuselage bolt and another stud going directly to the ground bus.
I would run a ground wire from the stud on the sender back to the GEA 24 case (or P244 pin 7) just as a test.

Checked the sender again with a meter and as fuel is removed, the voltage increases.
On our RV-7A with these float gauges we see ~0.3 Vdc with a full tank and ~2.2 Vdc with an empty tank on the fuel probe calibration page.

When you disconnect the fuel quantity probe from the GEA 24, you should see ~11.8 Vdc (from the internal pull-up resistor) on the fuel probe calibration page.

Still no luck on getting any reading through the EFIS.

Are you looking on the fuel probe calibration page?

Please contact us via email so we can request some screen shots!

Thanks,
Steve
 
The pins on the GEA are on 244 pin 6 and 9. Also understand that there are four inputs available for fuel. Actually using #3 for my rudder trim. the fourth is not being used.

Software Version on the GEA is 3.1

Ran a ground from the stud to the case on the GEA and no change.

When disconnecting the wire from the sender, the volts do not change on the EFIS. Stays at .005.

Here is a link to some pics
A


I can certainly email you but wonder if they will be responded to today. In kind of a pickle, they are tearing up our route to the fuel pumps tomorrow so wanted to get this done before the construction starts.

Thanks for all the help so far.
 
The pins on the GEA are on 244 pin 6 and 9. Also understand that there are four inputs available for fuel. Actually using #3 for my rudder trim. the fourth is not being used.

Software Version on the GEA is 3.1

Ran a ground from the stud to the case on the GEA and no change.

When disconnecting the wire from the sender, the volts do not change on the EFIS. Stays at .005.

Here is a link to some pics
A


I can certainly email you but wonder if they will be responded to today. In kind of a pickle, they are tearing up our route to the fuel pumps tomorrow so wanted to get this done before the construction starts.

Thanks for all the help so far.

Hi Brian,

When disconnecting the wire from the sender, the volts do not change on the EFIS. Stays at .005.

Why don't you unplug the entire P244 connector from the GEA 24 and let's see on the fuel probe calibration page if the voltage pulls up to 11.8 Vdc like it should. Seems like something is shorting out the input.

I can certainly email you but wonder if they will be responded to today. In kind of a pickle, they are tearing up our route to the fuel pumps tomorrow so wanted to get this done before the construction starts.
I will respond. It is too hot to go fishing....

Thanks,
Steve
 
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Memorial Day, holiday weekend, and the G3Xperts from Garmin are monitoring the forums to help out their customers. When I built my Garmin equipped RV-10, they were there for me when I needed help. It was a no brainer for me to choose Garmin equipment again for my 9-A.
 
Good Morning. The problem was solved. It ended being the shield on the wire to the sender was shorted to the actual inner wire. Fixed and tanks were calibrated.



Have to give a big shout out to Steve from Garmin for all his help. Being available for email and phone support on a holiday, you cant ask for any better customer service than that.


Thanks much for your help Steve.
 
Awesome! Was it shorted on the sender itself or in your harness? (i.e., did you have to take the sender out)?
 
It ended up being shorted somewhere in the harness that runs from the GEA to the fuselage side skin where it goes into a bulkhead cannon plug.
That harness carries a lot of wires to the tail and wings and really makes me nervous to remove it. Plus I would have to remove connections that are soldered together. Afraid I would create more problems with removing it.
I removed the shield grounds for now and going to see if I have any issues with interference and if so, will pull the harness to find the issue. Hoping that this will not be the case.
 
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