Repairing low gas indicator light... expert needed !

[SilverDave]

The red low gas level light on my 1200 comes on at startup check..... but not at "almost Empty " so bulb is good.
As I understand it , this light is controlled by a wet-dry two resistance thermistor.... a NTC type.

Something like this :

http://www.newark.com/amphenol-advanced ... 582-97-T10

They cost more to ship that to buy ( about $2).

I want to chat with someone who has actually done this fiddly repair .... and what I'd like to know , if I decide to do this is any snags I might run into ........Is the soldering difficult ? How does one open the little can ? Is there any orientation needed ? Will this modern NTC from Newark actually fit in the little can? Any re-seal gaskets needed ?


Its not in either one of my GL1200 manuals .... they recommend replacing the entire unit ( !! )

I am assuming the little hanging down can in this pic is the thermistor unit as the other part looks like the float for the gas gauge.

http://i.ebayimg.com/00/s/MTIwMFgxNjAw/ ... l/$_35.JPG

Thanks for any help .

SilverDave

[HALBUDD]

I think there was a post on how to fix this a while back. I think if you try and do a search on this site it may come up. I remember WingAdmi had written some thing up on this .Good luck----------------------Hal

[WingAdmin]

If it's the same as the GL1500 (and I suspect it is), it's a simple thermistor. When it's immersed in fuel, the fuel itself conducts heat away from it and keeps it relatively cool. When the fuel level drops below the thermistor, it warms up because the fuel is no longer conducting heat away from it, and its resistance changes. The dashboard detects the change in resistance and shows the low fuel light as a result.

It's not a very reliable system. That said, it can be replaced with a thermistor component that shouldn't cost you more than a couple dollars or so - if you know the correct resistance and whether it is a NTC or PTC. I'm 99.9% sure they are a NTC, in that its resistance drops when temperature rises, instead of the other way around.

That said, virgilmobile and I replaced these rather unreliable thermistors in our GL1500's with a float sensor and a flasher circuit that works extremely well. When my low fuel light starts to flash (and when it does, it's very attention-getting) I know I have exactly one gallon of fuel left (I calibrated it this way). You can read about it here:

viewtopic.php?f=14&t=11167

[SilverDave]

Yes , those thermistors are only about $1.10.... plus $20 shipping ....( agh !! ..).. I am looking into Ebay ones with the same hot-cold resistance .

Are they un-reliable because they fail from years of living in gas ?
or is the solder job the likely culprit ?
Or the possibly faulty ground of the can ?

I do like the float method that you and Virginmobile designed... but I'd like to try the simpler fix first....

SilverDave

[virgilmobile]

The component fails from age.It can be replaced but remember,It must be put back into the little canister.It is a "steady pond" design.If the thermistor is left hanging,sloshing gas will false trigger it.
This design will also not work well if you have replaced your low fuel lamp with a LED.

[WingAdmin]

Yes , those thermistors are only about $1.10.... plus $20 shipping ....( agh !! ..).. I am looking into Ebay ones with the same hot-cold resistance .

Are they un-reliable because they fail from years of living in gas ?
or is the solder job the likely culprit ?
Or the possibly faulty ground of the can ?

I do like the float method that you and Virginmobile designed... but I'd like to try the simpler fix first....

SilverDave

I suspect it's simply years of gas immersion and heat, combined with years of power going through them. They just stop conducting. The one on my GL1500 looked perfectly intact, and when I disassembled it, all the solder joints were fine, so it was the component itself that failed.

[Justin1200]

Hi guys, what type of thermistor do I need for this fix, before I order the wrong one.
GL1200 LTD 1985

[Rambozo]

One other thing is have you run it out of gas? You may want to drain the tank to verify it's really dead. I had never had the low fuel light come on before until one day I ran it really low on fuel. I believe I was down to half a gallon remaining before it started to glow dimly and got brighter as I continued, long after the gauge was past empty.