Left Fuel gauge in cockpit no worky

[Loogie]

Gents my left fuel gauge has decided for the last 10 hrs to work intermittently.  What is funny is that it works when I push down on the glare panel.  It also shifts its indication If I push on the main instrument panel but then it returns to its faulty reading.i have checked the connections and the ground behind the panel.  I am out of ideas, just curious if this has happened to anyone? If so how was it fixed?

Pic, left gas should read 24

its not a big deal, it's just annoying, since I have a 450 and a JPI730 both w fuel flow.

 

 

[DonMuncy]

Not to suggest you don't know how to check things, did you actually disconnect the connectors from the gauge, clean them with abrasive and reconnect them.  I would also check the voltage to the "hot" side of the gauge (and while bumping the glare shield.) Since the gauge reads the variable ground through the fuel sender units, I wouldn't think a ground to the gauge should be a factor. Since it changes with movement of the panel, it is unlikely to be in the level sensors. That leaves (I think), power to the gauge, connectors to the gauge or the gauge itself. If I'm wrong, someone will certainly chime in.

[Loogie]

Don, thanks, will do that tomorrow, I just made sure the nuts were tight, cause I'm a fighter pilot not a professional hangar elf:)

i will do as suggested.  Based on my research, I was down to juice to the gauge, or the connectors as well. 

 

Off course you you need tiny monkey hands, tiny tools and super magnets to work in that space!  Geeze they are fast a/c but a pain in the arse to work on in tight quarters!

Edited March 23, 2016 by Loogie

[DonMuncy]

In-op fuel gauges are a frequent complaint. Be sure and report back when you get it sorted out. 

[ArtVandelay]

I have same problem, already tried cleaning contacts, when I tap on gauge it alternates from working to not.  I think there is a place that you can send to have them overhauled.

[carusoam]

 

check on this thread for interesting details for Garwin six pack fuel gauges....

Seems like there may be a limited life of the device itself. 

Best regards,

-a-

[jwilcoxon78]

I have a similar issue with my UBG16.  Starts to get an erratic display while flying xc so I've got some time on my hands.  Messing around, I noticed that when I put pressure on the panel around the instrument, it stopped.  All 4 screws were able to be advanced 1/4-1/2 turn.  Seemed to fix the problem.  Thinking it's a grounding issue.  

[TWinter]

My left one is a little sleepy. Usually a little tap on the glass and she wakes up after it has been parked for a few days..Just the left, however, it is accurate after it wakes up. Funny it seems to be the left side everyone has a problem with. I'm hoping after I save my allowance and get JPI primary all will be good.

 

 

-Tom

[mooniac15u]

On March 23, 2016 at 10:11 PM, Loogie said:

Gents my left fuel gauge has decided for the last 10 hrs to work intermittently.  What is funny is that it works when I push down on the glare panel.  It also shifts its indication If I push on the main instrument panel but then it returns to its faulty reading.i have checked the connections and the ground behind the panel.  I am out of ideas, just curious if this has happened to anyone? If so how was it fixed?

Pic, left gas should read 24

its not a big deal, it's just annoying, since I have a 450 and a JPI730 both w fuel flow.

 

 

The power to those gauges comes from a single wire attached to the far right gauge. The rest of the gauges are just daisy-chained together. The power for the last one comes from a short wire off the other fuel gauge which is clearly getting power. So, if it's a power problem it's in that last wire. You might want to check the connection at the other fuel gauge. 

You could try using an alligator clip test lead to bypass that last wire. If the gauge starts working it would confirm the problem is on the power side. 

[Andy95W]

5 hours ago, TWinter said:

Funny it seems to be the left side everyone has a problem with. 

Stirring up trouble in an election year?

 

[TWinter]

1 hour ago, N1395W said:

Stirring up trouble in an election year?

 

I'm just wondering who was on the assembly line in charge of the left side fuel gauge. Maybe a newbie?

[riredale]

Hi, everyone.  First post here.

 

Used to fly an M20J, from 1982 to about 1998.  Took it everywhere across country from its base first at Santa Monica CA and later at Aurora Oregon.

I signed up to this forum just now in order to respond to the fuel gauge question.  I also had weird indications back in the mid-90s and took the cluster out of the panel a number of times (and as someone has said, it helps to find someone with small hands--what a pain).  Never could figure out what was wrong.  The gauges were D'Arsonval meter movements, very simple in design.

I was about to give up when I thought to look at the movements with a 10X loupe.  Surprise!  There were dozens of microscopic spider-web strands snaking across the movement.  Not a "web," per se, but just a trail left by some itty-bitty spider who had somehow crawled into the gauge box through one of the vent holes.  The little guy had crawled around and over 4 of the gauges, and once I carefully cleaned out the filaments with a toothpick, they all swung freely again.

I'd find it hard to believe that you have the same issue, but you never know.

Best regards to the Mooney community.  If I flew again I'd probably go for an Encore with a weeping wing (lots of ice up here in the Pacific NW).

[carusoam]

Welcome aboard riredale.

Your Mooney experienced input is greatly appreciated.

Best regards,

-a-

[Loogie]

Will certainly look at it with a ten power loupe! Will report back.

 

mooniac, 15U, here are some back panel pics, could you put little blue arrows on the pics of your explanation if able? Would be really helpful if you can. 

 

[mooniac15u]

The power comes into the gauges at the terminals labeled "IGN". Each one is connected to the previous from left to right looking at it from the back. The malfunctioning gauge is on the far right ("B" in attached photo). It is getting power via a wire from from "A" to "B".  If you put a jumper across those terminals you can bypass a potential bad connection.  I've also attached a small section of the schematic for the gauge cluster.  Sorry the quality of that image isn't very good but it shows how things are connected.  Keep in mind that the schematic is showing the orientation from the front.

On the photo I've also added a red circle where it looks like there could possibly be an issue.  Is that ground wire in the circle making contact with terminal "A" or any of the connected wires?  It is very hard to tell in the photo.

[carusoam]

You guys are good!

Best regards,

-a-

[Loogie]

5 hours ago, mooniac15u said:

The power comes into the gauges at the terminals labeled "IGN". Each one is connected to the previous from left to right looking at it from the back. The malfunctioning gauge is on the far right ("B" in attached photo). It is getting power via a wire from from "A" to "B".  If you put a jumper across those terminals you can bypass a potential bad connection.  I've also attached a small section of the schematic for the gauge cluster.  Sorry the quality of that image isn't very good but it shows how things are connected.  Keep in mind that the schematic is showing the orientation from the front.

On the photo I've also added a red circle where it looks like there could possibly be an issue.  Is that ground wire in the circle making contact with terminal "A" or any of the connected wires?  It is very hard to tell in the photo.

OK, that is perfect explanation! Thanks for the schematic, that helps.  I will jump on that on mon, when I get back. Appreciate the effort and help!