Erratic fuel gauges

[Pete Somers]

Hi Ernie
Thanks for the info.
I had to remove the whole cluster to clean one up, also found that the connections to the various indicators from the printed ciruit not very good and had to remove and clean these. The cluster does come out easy once the pipes are removed.

Pete

[edasmus]

Hi Pete,

My name is Ed Asmus and after reading this thread it sounds like the problem I have in my C337G 1973 model. Erratic fuel guage readings began on my last flight last week and my shop is 99% certain the problem is in the "Fuel Control Monitor" also known as the "Signal Conditioner" part number C668004-0102. My mechanic re-soldered the female plug that connects to the control monitor with no improvment. Is it possible to re-solder the pins on the male plug that is attached to the control monitor board? My mechanic thought it could be done seeing as overhauled ones can be purchased so somebody knows how to do this. It looks like to replace the entire control monitor unit would be $1200+ which would make me sad knowing that somewhere there is a simple lose connection. How do you remove the male plug from the control monitor board? Any suggestions?

Thanks Ed

[Ernie Martin]

If you read my post above Pete's you'll see that I've also been struggling with the problem. My best advise to you is to make certain that it's the box before you spend the big bucks. Because of the small voltages, the system is sensitive to the aging effects of corrosion and wear on the connectors, resulting in increased impedance and erratic readings. It would not be inaccurate to say that I've kind of given up on the problem, and I now get good readings if it's mostly full and erratic ones under 1/2 full. So I never take off without climbing on the wings and doing a visual check.

Ernie

[JeffAxel]

Ernie,
Aero-Mach Labs in Wichita can fix these things. They fixed mine and it works great now.

www.aeromach.com

[edasmus]

Thanks Ernie...I did read the entire thread and I was aware of your heartache over this issue. I agree that I certainly do not require super accurate readings to know how much fuel is on board but it does make for a nice cross check. I suppose more importantly, fuel gages would be my only line of defense should I spring a leak during flight and fuel was exiting the wings without going through the engines. My problem appears to be in the aforementioned fuel control monitor, C668004-0102. My gages indicate quite accurately when they receive electricity but it seems to be an all or nothing affair. If you wiggle the connection on the box, the gages come back to life. Jeff Axel has given me a lead on a possible repair facility to fix my existing box so I'll see where that leads in the morning. Thanks! Ed

[Pete Somers]

Ed
I have replaced that connector, but you need to know what you are doing. You need a proper desoldering rig to do it. As I have said on this thread, the only way to fault find and calibrate this system is with a capacitance test box, it makes the job so easy, saving you time and money at the end of the day. Once calibrated this system is very accurate

Pete

[edasmus]

Thanks Pete....I'm going to contact Aeromach today and hope for the best! Thanks!