Fuel gauge issue

[charles]

Ok, so the fuel gauge didn't work when I bought my 2001 PX 200. Stripped out the sender, figuring that was the likely cause, cleaned the contact bar and tweaked it. Tested it before replacing and that seemed to work. After a 5 minute ride, the needle on the clock dropped back to zero. Bit the bullet and bought a replacement sender, which again worked for 5 minutes. Checked all the wiring connectors visually (need to get a volt meter, I guess) and they all seemed okay. Anyone got any ideas? Could it be the meter gauge on the speedometer is duff?

FYI: The speedo is the older Veglia type: black face with the needle sliding vertically across a semi-circular display.
Grateful for any help... p*55ed off removing my filler cap to see how much in the tank. 
TIA
Charlie

[mijapxman]

Charles, May? Be the wire connection going into the back of the Speedo check the connector block and check the printed circuit that's on the back of the Speedo for any breaks?
PX fuel gauges are notorious for being crap, I never trust them and always Check the tank😉.
Let us know how you get on, if it's none of the above get back to us or do as I do and live with it as a Vespa " quirk) .
All the best.
Jim (aka) Mij 😉lol.

[charles]

Thanks for replying, Jim. Checked the circuit strips earlier today and no breaks. Connector block seems fine too, but will buy/borrow a volt meter tomorrow to be sure. Would a bad connection cause an initial false hope (it's sorted) like this? Just seems weird that after tinkering with the original sender it worked for 5 mins. Same after replacing it with new original (not cheap here in Thailand, mate!). I'm one of those 'if it's on the scoot, it should work' kinda blokes. Guess that's my quirk

[mijapxman]

I have the same quirk,"if it's on the scoot, I need it working", lol. Was just trying to make you feel better if you couldn't fix it, mate 😉☺.
Think your going to have to see what your meter says, but I'll put my thinking cap on👍.

Not at my best today, got a back tooth out Monday and had to go back to dentist today to get my gum cut to get a bit of root out that was left from an extraction last year, then stitched. Turns out one of the tablets I'm on, has a side effect of damaging your teeth!😭
Good luck
Jim😉

[charles]

Thanks, Jim.

Wish you a speedy recovery, mate. I had the same thing here; Dentist said he'd removed all of a molar, but turns out he missed a root section. Nowt much worse than toothy problems... except maybe Vespa problem solving!

Will let you know how I get on today.
Cheers,

Charlie

[charles]

Just a quick follow up: Checked all connections with a multi-meter yesterday and all seemed sound. Good continuity right the way through from fuel sender to contact terminals on the fuel gauge (back of speedo). Ground good too. Registered 3.6v on the gauge terminals with engine running. Not sure if that's correct, but wouldn't expect 12. Anyone else know? Still scratching me head, but strongly suspect the gauge within the speedo is duff now after 17 yrs.

Maybe time to splash out on one of them fancy SIP rev/speedos... costs as much as I pay for a month's rent on the house out here, but WTH

[mijapxman]

Charlie, gave a mate a loan of my multi-meter a few weeks ago!( All ways a risk😉) and he's on holiday for 10 days,( 7 days left) so can't check voltage on mine,at the moment but it does sound about right.
Could you not borrow a Speedo and try it,to confirm it your Speedo gauge is faulty? altho if your getting 3•6v from the wires at the Speedo end, I'd expect it to work all the time.
Kinda sounds like a short circuit, have you checked the wires aren't frayed in the gap between the frame and the headset bottom? And checked voltage while turning the headset?

With a bit of luck someone else may chip in?

Good luck
Jim☺

[pxmatt]

I noticed when I rode mine yeterday after leaving the petrol station that my fuel gauge was bouncing from left (empty) to right (full). This is the first time I have noticed this happening. I did have to change the fiel tap recently as it was leaking fuel from the tap arm connection. So not sure if I may have disturbed the sender inside the tank some how? even with the tap removal tool, it was still a ball ache because the securing nut is in a recess in the tank.

I know it doesn't help your situation but found it stange that mine started doing it yesterday after 20 years.

Let us know how you get on

[kru251]

Did the fuel gauge needle fly up to indicate a level on turning on the ignition, then fall back immediately when ignition turned off?
If so, the gauge needle damper resistor has gone u/s.

[ironsloth]

Seen it more with LameBedWetters, especially the tuned ones. The fuel gauge waves at you to let you know it is connected, that’s it. Have you cleaned the terminals, and is the float still attached?

[kru251]

Fuel gauge on a Lammie?
Mk 1 eyeball !