[rstisser]

I have an issue in my Vans fuel gauges that is strange. When the tanks are above 10 gallons and I turn on the master, the gauges register accurately. After engine start the gauges go to zero. Cycling the master brings them back to accurate. If I forget to cycle the master they will begin to operate accurately when they go under 10 gallons. This issue has been going on for some time and began with the right gauge and is now affecting both. I'm hoping the brain trust here has a solution. I am hesitant to start tearing into the system without guidance as I know it could get messy. Thanks Randy

 

[jbDC9]

This seems to be typical behavior for the stock Vans fuel gauges, I've replaced a few of them for similar behavior. I'm sorta spitballing here, be methinks that they don't like the system voltage drop during engine start, assuming they're wired to the main bus; during/after start they'll act funky with a sweep then indicate zero. Recycling master switch off/on would fix it, but the problem would reoccur at each start. I've replaced both of mine, then rewired to power them from the avionics bus, which I have off for start. Problem seems to be solved, for now...

 

[rstisser]

This seems to be typical behavior for the stock Vans fuel gauges, I've replaced a few of them for similar behavior. I'm sorta spitballing here, be methinks that they don't like the system voltage drop during engine start, assuming they're wired to the main bus; during/after start they'll act funky with a sweep then indicate zero. Recycling master switch off/on would fix it, but the problem would reoccur at each start. I've replaced both of mine, then rewired to power them from the avionics bus, which I have off for start. Problem seems to be solved, for now...

Thanks. I will change power source for gauges.

 

[graywoodworking]

I had a flakey fuel gauge not too long ago. Turned out to be a bad ground. For some reason the Vans plans rely on the mounting screws for a ground path instead of a jumper. I tightened a couple of the screws and that scratched the surface enough to fix the ground.

 

[rstisser]

I had a flakey fuel gauge not too long ago. Turned out to be a bad ground. For some reason the Vans plans rely on the mounting screws for a ground path instead of a jumper. I tightened a couple of the screws and that scratched the surface enough to fix the ground.

I will try that also.

 

[JET14]

I've re-grounded and recalibrated multiple times and I can't get the "flake" out of mine either. Especially for a tail dragger.

 

[Stevea]

I have an issue in my Vans fuel gauges that is strange. When the tanks are above 10 gallons and I turn on the master, the gauges register accurately. After engine start the gauges go to zero. Cycling the master brings them back to accurate. If I forget to cycle the master they will begin to operate accurately when they go under 10 gallons. This issue has been going on for some time and began with the right gauge and is now affecting both. I'm hoping the brain trust here has a solution. I am hesitant to start tearing into the system without guidance as I know it could get messy. Thanks Randy

Had the same issue intermittently with my Vans fuel gauges. Cycling after the master switch after engine start always fixed the “pegged at zero” problem. Swapping one gauge for a new one didn’t make any difference….so I just lived with it by verifying a non-zero gauge reading after engine start.

Interestingly, the problem happened much less often after a battery replacement (old Odyssey P680 died…..replaced with same type). I continued the “if necessary” power cycle to reset the gauge. Fast forward to replacing the second P680 with an EarthX, and the problem has not happened since.

This is not a grounding issue. It is a “brown out” condition during engine start when the buss voltage is pulled low (low enough the vans fuel gauge “doesn’t like it”) by the starter current draw.

 

[graywoodworking]

Had the same issue intermittently with my Vans fuel gauges. Cycling after the master switch after engine start always fixed the “pegged at zero” problem. Swapping one gauge for a new one didn’t make any difference….so I just lived with it by verifying a non-zero gauge reading after engine start.

Interestingly, the problem happened much less often after a battery replacement (old Odyssey P680 died…..replaced with same type). I continued the “if necessary” power cycle to reset the gauge. Fast forward to replacing the second P680 with an EarthX, and the problem has not happened since.

This is not a grounding issue. It is a “brown out” condition during engine start when the buss voltage is pulled low (low enough the vans fuel gauge “doesn’t like it”) by the starter current draw.

Good reason to put the engine monitor on a backup battery along with the PFD. That’s the way my Garmin G3X system is configured so the PFD doesn’t reboot during an engine start.