Petrol level needle giving false readings

[belfastmark]

Hi.
2001 1.6s 16v 78,000 mls Golf mk 4.
My petrol needle is giving false readings.
It tells me it is half full when it is empty, and if I put £20 in, it tells me
it is full. At the minute, I put £20 in and when I get about 100 miles, it is filled
up with another £20.
I am intending to have her plugged in soon. Will anything show up ?
Also, if she reads half full when empty and £20 brings the
needle to full, if I was to fill her with say £40, will the fuel nozzle stop delivering ?
When you are filling the car up and you want a full tank, once the tank is
full, the petrol pump clicks and stops delivering.
If I am getting a false reading, would the pump cut out because
something in the tank thinks it's full when actually it isn't ?
I have tried to describe this as best as I can.
Waiting for your replies. Thanks

[mikeybutch]

Seems yiu have a duff sender in the tank which could be easy fix .You will just have to fill up and keep check on the miles before its fixed

[phil miller]

prob as above, but can i ask does your speedo work?

[belfastmark]

Hi Phil.
Speedo is fine. Why do you ask ?

[phil miller]

Hi Phil.
Speedo is fine. Why do you ask ?

Well ive had 2 mk4 golfs since christmas where there fuel gauge has been like this and there speedo hasnt worked and its been a broken earth wire to the speedo sensor, but as yours works its defo not that, prob the sender dude

[belfastmark]

Phil.
What is the likely scenario for me.
The mechanic will be plugging it in in the next couple of weeks
will it show up a fault ? I think his diagnostics are not as a genuine VW.
What are we talking money wise, roughly ?

[phil miller]

There is a chance the fuel gauge may throw a fault using vcds, after a scan if all seems ok i would take the sender out of the tank and move the float, first from empty then up to full the gauge should read, if it doesnt then try joining the sender wires this should make the gauge read full, if the gauge reads full then its the sender in the tank, about an hour to do this testing, im not sure on how much it will be for the unit tho

[belfastmark]

Phil.
The testing detailed above, that's well within the relms of any competent mechanic ?
The mechanic I use is independant and ex VW.

[phil miller]

Phil.
The testing detailed above, that's well within the relms of any competent mechanic ?
The mechanic I use is independant and ex VW.

TBH anyone with mechanical know how would be able to do it, your mechanic should be able to test this not a problem mate