Fuel needle bounced up rapidly at start-up

[9000se]

Hi All,

Had an issue with the Activa.

Was at the lights and stalled it, tried turning over twice before starting, when it started up, the fuel needle bounced up to above the full mark...

Went home, disconnected the battery (been 24 hours) and plugged it back in just now...

1) First time, it bounced up very quickly (can't see it really, its just bounced up - not a slow creep) to just above the full mark (normal level as I just filled up to the brim...)

Turned off engine...

2) Second time, 10 seconds later, it bounced up very quickly again, but this time above the full mark...(beyond 11 o'clock position, at full brim it is more like 10 o'clock)

The needle also doesn't go down when switched off, unless I tap the dash...any idea how I can fix this as I don't think I can read the fuel level.

Many Thanks!

[GiveMeABreak]

I know that brimming a tank can cause fuel gauge issues. I had this with the X7, needle never went back to full,dealer got it on Diagbox and reset some parameters and cured it. now I never fill past the first or second click.

They do say not to fill past the third click in many of the manuals

[Paul-R]

I habitually fill to the third, fourth, fifth click and beyond until I can't get any more fuel in on both cars. Always have done to get as correct as possible brim to brim mpg figures.

I've also seen the warning about overfilling and ignored it as no reasonable explanation has been given.

[Hell Razor5543]

The problem with overfilling a car fuel tank (from the perspective of a motorcyclist) is that sometimes some fuel can (in a corner) slop out of the filler cap and make the road surface unexpectedly more slippery. I am not a motorcyclist, but I know of one who has advised of this potentially dangerous situation.

[Michel]

Yes. I'm a motorcyclist. My left ankle will tell you why it's a bad idea to fill right to the brim, especially with diesel. It can (and does) escape from the filler and breather and makes it bloody lethal to those in two wheels, especially on roundabouts, and even more so when it rains.

You know you see lots of vehicles with staining below the filler cap? That's because of overfilling. It ends up on the road. Caused a lovely fracture in my ankle in 1999 when the front of my motorbike went from under me on a diesel spill on a roundabout.

Watching out for diesel spills is one of the very first things the instructor will tell you during the motorcycle training these days, when teaching about road hazards and conditions. That's before they let you loose on a motorbike.

[xantia_v6]

On a S1 Xantia, the fuel gauge system is relatively simple, there is a variable resistance in the tank, a wire to the gauge, and the gauge. The gauge does have some electronics in it (to average the readings and drive the low fuel light), but there is no central controller.

Given you description, I would have to guess that your gauge is faulty, maybe a soldered joint in the dashboard has failed.

[9000se]

Thanks for the replies, I only filled it up to the first click (didn't want any to spill out).

I will take a look at the dashboard if its easy to remove, I have a feeling the multiple crank led to this issue...grrrrr

[white exec]

The list of X7 shortcomings just seems to get longer...
Splitting hydraulic reservoirs
Corroding steering pinions
Sticking fuel gauges
Electro-hydraulic pump issues
Ultra-high current fuses
iirc
I know it's an attractive-looking car, but I really wouldn't want to own one. That said, I take my hat off to those enthusiasts who do.

[xantia_v6]

Which vehicle are we talking about here???

[GiveMeABreak]

Mine was fixed with a software download Chris, but I think that apart from the steeeing rack and struts, there’s not too much not in common with other cars. The C6 also has the splitting tank issue, but I think that is more a matter of PSA not communicating the correct lifting procedures outside of their vehicle network properly and not putting that critical info into the owner handbook.

I’ve had my fair share of LHM leaks, pump and hose issues, with more traditional Citroen’s I’ve owned, by the rack issue does take the biscuit.

In some ways electronics can be simpler to diagnose and replace than a purely mechanical solution, but hey, that’s the way it is I guess.

[Paul-R]

...why it's a bad idea to fill right to the brim, especially with diesel. It can (and does) escape from the filler and breather ...

This doesn't happen with cars nowadays as the filler cap is sealed. You have to go back to the 70s to find cars with vented filler caps.

You know you see lots of vehicles with staining below the filler cap? That's because of overfilling. It ends up on the road.

Not overfilling but sloppy filling. More allowing blowback by trying to fill too fast or extracting the filler nozzle before the flow of fuel has stopped. I've seen that more than once.

It can also the fault of the fuel pump not reacting to back pressure quickly enough and allowing blowback.

[Michel]

...why it's a bad idea to fill right to the brim, especially with diesel. It can (and does) escape from the filler and breather ...

This doesn't happen with cars nowadays as the filler cap is sealed. You have to go back to the 70s to find cars with vented filler cap

The amount of diesel I still see and smell spilt on roundabout especially, tells me it does happen, sorry.

[Paul-R]

Like I said, there are other reasons - most notably clumsiness. Someone has overfilled and it's still dripping out of the overflow. Or maybe it's not a car at all but a wagon of some kind.

Having said that I don't see much evidence anyway. I remain profoundly unconvinced - sorry.

[GiveMeABreak]

The pump nozzle should suck up vapours and excess fuel back into the petrol station pump when triggered after the clicks if held in the tank properly. Those that partially remove the nozzle and keep brimming it will likely be the cause of fuel spills and drips all over the place - you just have to look at all the fuel streaks down the sides of cars under the fuel filter cap.

Not so sure on modern vehicles, but in the past I’ve seen lorries driving down the road with drips from their diesel tanks spewing onto the road.

[Paul-R]

I only ever use the petrol nozzle to fill up a spare fuel can to power the grass cutter but I can't recall either petrol or diesel nozzles being equipped with vapour recovery systems. I've seen photos of such systems and they seem to have an extra flexible tube over the nozzle which then makes a seal against the bodywork. Never seen them anywhere in Europe.