Fuel Level Sender

[cresco750]

Today I spent the afternoon trying to get the low fuel sensor working. When I got the bike this had been disconnected; the wires from the loom had the plastic plug removed and the wires taped. I have a couple of other sensors in my box of bits that came with the bike and they both have melted plugs on them although i can't tell whether they have melted as a result of an electrical short or radiated heat from the engine? 
I can get the red warning light on the instrument cluster to illuminate when I make a contact between two of the three terminals from the loom, so that part of the circuit seems to work OK, however when I plug the sensor in I can't get the light to come on no matter what angle I tip the tank at in order to uncover the probe. From this I have to assume that there is a problem with the sensor unit, but is there a way I can check this?
The melting of the plugs is a concern, and I have read about this in another thread. Is this a know problem? Any thoughts as to the cause?

cheers

[neandethal]

inside the manual there is a test procedure for the thermistor, i am guessing like mine it has given up the ghost

[cresco750]

Yes, I think you may be right. As far as I can see, the test procedure in the manual wouldn't really prove anything more than what can be deduced while the sender is installed in the bike, ie if the light comes on; the sender is ok, if the light doesn't come on then it's cactus?

[wayne]

The test in the manual though eliminates any possibility that the fault is in the bike's wiring between the unit and the fuel light.



If you have to pull it out, this may or may not help you.

I had a similar problem with an '88 GL1500 fuel level warning light. It was $300 for the Honda replacement.

I found an article on the net which told you what the technical specs of the actual thermistor were.

Off to the local J-Car electronic store and I bought a replacement for 95 cents, soldered in place and that was that.

Perhaps if you unsolder it and take it down to a Tandy or J-Car they could find the equivalent ?

Here are the specs from that article for the GL1500, I wouldn't be surprised if this worked for the RE: 1000 ohms at 25 degrees C, NTC (Negative Temperature Co-efficient).

[cresco750]

That's exactly what I was wondering too, Wayne. It would be great if a modern, off the shelf part could be found to rebuild these units.

[wayne]

Try those specs above, 1000 ohm at 25 degrees NTC, the 1500 is Japanese and 12 volt and the unit does exactly the same job. I'm sure it'd work and it takes nothing to unsolder the RE5's unit.

[ohiojoe]

I thought I had a bad thermistor on my Verago…it takes about a minute for it to warm up.

[timpa136]

Post by neandethal on Apr 3, 2015 at 10:10am

Hi,

my low fuel level sensor was useless and showed signs of somebody having had a go at the wires but it was the thermistor that was knackered.

Taking the view i had nothing to lose i took the old one apart and got my mate who works at RS Components to order me up a 220ohm thermistor at the grand cost of 78p. Whilst the disassembly was very crude i soldered in the new thermistor spaced it away from the housing using fine petrol tube and car body-filler to seal it up and tested it all out, and all works fine and it doesn`t appear to be polarity sensitive.

will try and find the code of the part i used and there are posts on youtube of fuel level sensor repairs for other bikes.

Hope this might help other suffers of this fault.

It sounds like a thermistor value close between both of yours and doesn't have to be exact, should light the cluster bulb.

P.S. I like Ohio Joes repair to a leaky sender with the reinforcing thread and epoxy combination.