Hot Fuel Gauges

ProCoach · #1 08-25-2006, 12:42 PM

Okay, I hate this electrical stuff... My Vans fuel gauges are both getting VERY hot. I discovered this in flight and shut off the master. After I landed I disconnected them. Everything thing else is working perfectly. I've checked the connections and installed a new main breaker. No breakers are tripped by the gauges, but you could fry an egg on 'em. In fact, the lower rear gauge casing is warped from the melt. Needless to say they are presently disconnected. They seem to work fine... just heat up after a couple of minutes.

Anybody know what's going on??

Build9A · #2 08-25-2006, 03:25 PM

check your alternator voltage output. High voltage could be the culprit. If it is, your other guages and electronics could also be in harms way.

ProCoach · #3 08-25-2006, 03:34 PM

Thanks, but according to its gauge the alternator is right on. All other gauges are working cool and perfectly. The fuel gauges will heat up just off the battery (i.e. on the ground w/ engine off).

Ted Johns · #4 08-25-2006, 05:52 PM

Boy, that makes no sense at all (no pun intended). I would check the current draw of the gauges, which are just milliamp meters measuring the current thru the resistive tank sensor. I would think that the circuit shouldn't draw more than 2 or 3 watts,
otherwise, things are going to get warm. Three watts would be about 200ma with the alternator spinning.

Sounds like something is wrong with the meters?!

lucky333 · #5 08-25-2006, 06:29 PM

Both running hot with one melted is more than alternator voltage, especially with everything else OK. I could buy one geting hot with a failure but not both. How do you have them wired up and do they indicate the fuel level that you think they should? Are you using the standard SW float sensors?

John

ProCoach · #6 08-25-2006, 06:41 PM

Think so (I just bought it). Wired - power to the right side gauge. Jumper to the left. The right was slightly hotter than the left. They both read accurately, even still. However, in flight (after they were really hot) they went "dead" and that's when I reached up there to see if I could feel something loose. When I did, I got burned and shut down the master.

This was after a soaking rain the night before and the humidity was very high that morning. Maybe something got wet (?). I first thought that because the faces of each gauge held moisture inside. But that condensation may have been the result of the heat up taking place.

So maybe the gauges are toast? I can replace them easy enough, but then it seems like I would be treating a symptom instead of a cause. I guess there's one way to find out.

rvator51 · #7 08-25-2006, 06:49 PM

Quote:

Originally Posted by ProCoach

Okay, I hate this electrical stuff... My Vans fuel gauges are both getting VERY hot. I discovered this in flight and shut off the master. After I landed I disconnected them. Everything thing else is working perfectly. I've checked the connections and installed a new main breaker. No breakers are tripped by the gauges, but you could fry an egg on 'em. In fact, the lower rear gauge casing is warped from the melt. Needless to say they are presently disconnected. They seem to work fine... just heat up after a couple of minutes.

Anybody know what's going on??

Same exact thing happened to my Vans Gauges on the way to Arlington in July. Replaced both with new ones although mine were less that a year old.
Never could figure out what happened to them to cause the overheat. I did open one up and found burned components on the circuit board.
Regards,
Tom Velvick
rv-4

ProCoach · #8 08-25-2006, 06:52 PM

Misery loves company... so thanks for that. I'll plan on getting some new ones.

lucky333 · #9 08-25-2006, 07:10 PM

Fog in the guages is not good. Those guages are toast.

My main concern is what else is getting wet? Fix the leaks first. Are we talking about $39 guages or $5K radios?

Don't care about a cheap guage but somewhere in the whole guage circuit you are getting enough current to melt the case.. this is connected to the sensor which resides in the fuel tank...

Don't like that.

This whole circuit is designed to be a low current sensor. By sensor, we mean *very* low currents that are reflected on the needle... not by melts in the case.

It may be that replacing the guage fixes the issue. Personally, I'd look more into it.

John

PS If you replace the guage, send me the old one. I'd like to dissect it..

ProCoach · #10 08-25-2006, 08:13 PM

Wilco... be happy to. What address?

If the circuit was getting that much current, wouldn't the circuit breaker pop? or next, the main 30A breaker? Just seems weird. How best to test?

I will get new gauges.

BTW, thanks!