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Post by papisto on Apr 5, 2017 12:51:38 GMT
Hello, I am atif from bangladesh. for last few days i am having some difficulties reading the fuel gauge. it keeps jumping whether its running or in stand. I have already changed the sending unit but no LUCK. can anyone help me to resolve this issue?
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Post by sime66 on Apr 5, 2017 18:36:38 GMT
Hi Atif, good to have you on the forum.
PX fuel gauges do swing around, if they work at all, and most of us just put up with it.
If you know how they work it can help to solve a few possible causes, which is either the float arm swinging about or the resistance fluctuating.
You’ll have checked your wiring when you replaced the sender, but did you check the sender float arm damper is seated properly in the little bucket? (It seems to prevent gauge swaying with fuel level swishing about in tank). Also, as it is on regulated AC it does depend on if your engine is running/Idling smoothly at even revs; like PX lighting it will fluctuate with stator output (or any other electrical faults – maybe regulator is struggling/knackered; the gauge works on resistance, which increases as fuel level drops, but resistance will change with voltage too) – though mine seems to sway about just as much at fairly constant high revs. There’s also the possibility that the electronic item (diode?) for the gauge on the back of the speedo might be faulty; we’ve discussed that on here, but not really found out exactly what it is or does, but it's a hunch I have anyway.
Maybe some of that might help – let us know if you find and fix it; we might learn something!
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Post by papisto on Apr 8, 2017 18:56:45 GMT
Thanks for the wonderful and detailed reply. This weekend I tried to dissemble the whole speedometer unit. I separated the fuel receiving unit and measured with multimeter but unfortunately there was no error in the unit. However I have checked the sending unit as well. The unit is not faulty and tested in other scooter. Finally I put two drops of hydraulic fluid in the receiving unit put everything back together.
The conclusion is I am getting a bit better reading but still it jumps.
I will try to get all electronic operation in battery mode just to check.
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Post by papisto on Apr 13, 2017 22:12:07 GMT
Hi Atif, good to have you on the forum. PX fuel gauges do swing around, if they work at all, and most of us just put up with it. If you know how they work it can help to solve a few possible causes, which is either the float arm swinging about or the resistance fluctuating. You’ll have checked your wiring when you replaced the sender, but did you check the sender float arm damper is seated properly in the little bucket? (It seems to prevent gauge swaying with fuel level swishing about in tank). Also, as it is on regulated AC it does depend on if your engine is running/Idling smoothly at even revs; like PX lighting it will fluctuate with stator output (or any other electrical faults – maybe regulator is struggling/knackered; the gauge works on resistance, which increases as fuel level drops, but resistance will change with voltage too) – though mine seems to sway about just as much at fairly constant high revs. There’s also the possibility that the electronic item (diode?) for the gauge on the back of the speedo might be faulty; we’ve discussed that on here, but not really found out exactly what it is or does, but it's a hunch I have anyway. Maybe some of that might help – let us know if you find and fix it; we might learn something! I tried switching to battery operation but no lick. My mechanic informed me about an old speedometer. I just dissemble the reading unit and replaced with mine. Now everything is in order. Although I ordered an extra fuel gauge from Aliexpress, just in case. Again thanks for your prompt reply. |
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Post by sime66 on Apr 14, 2017 12:10:05 GMT
Sounds like electronics within speedo then; my suspicion there remains in that case.
Glad you fixed it, not sure if we learned anything from it or not.
As I said: I've tended just to live with it, and judge my fuel level by my mileage between fills.
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Post by ianmartin40 on Apr 14, 2017 19:44:19 GMT
From my limited electrical knowledge a diode must be fitted the correct way round as it`s job is to allow the current to flow in one direction only, the cathode is the end with the band painted on as in your picture it is silver.
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Post by papisto on Apr 14, 2017 22:37:06 GMT
Well I tried to change the diode, you will find the diode in the gauge unit. Apparently old and new both model has the diode, new model units have it outside and old model located inside. However I have checked the diode with my meter everything was alright and changed with the same diode but no luck. Wasted my 2 hours of time. Anyway if you find luck please let us know. Cheers |
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Post by sime66 on Apr 15, 2017 13:43:16 GMT
Wasted?
Surely not time wasted, but a possibility investigated and results (successes and failures) added to the collective pot of knowledge; it’s what we do on this forum – give and take.
Thanks for sharing.
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