Sons fabia fuel guage seems to be showing full tank all the time. He reckons it should have dropped by now as he has being using the car. Mileage/distance left to go doen't seem to be changing either. Not sure where to start looking. I assume the sender unit is in petrol tank. Any help or previous experience with this most welcome. Going to get him to fill it to top and keep an eye on mileage in the mean time.

Do you know if your son has driven more than 70 miles since filling the tank?

It is fairly common for fuel gauges to not register any movement from full tank for first 50 to 70 miles after fill to brim.

Reckon hes done about 100 but going to get him to fill up today to brim and monitor it. Mileage left on dash doesnt change either. Hopefully its just the sender stuck and a full tank and a good bump in road will release it.

Alasdair

FWIW @Alasdair1 on mine the fuel gauge (and predicted range) used to rise for the first 50 miles or so, and then start dropping, taking about 100 miles to get to where the petrol (well diesel in my case) pump cut-off operated.

Might be a dry joint on the cluster circuitboard, where the input from the sender potentiometer comes in.

Not sure if open circuit would give a full or empty reading, but probably one or the other.

Pin 15 springs to mind, but memory isn't to be relied on.

Will check I am getting voltage to sender and also disconnect and see if it changes guage. Fairly simple to access sender via hole under rear seats. As said hes going to fill up to brim later on and see how much fuel it takes then just monitor it for now until I get time and hes not using it for work.

Thanks

Alasdair

If you have VCDS you can probably see fuel level in measuring blocks of module 17 (instruments).

You could then see if that changes if you jack up the rear of the vehicle.

Alas havent got vcds yet. Been meaning to get it but so far managing to cope with a cheap handheld chinese scanner. Its pretty slow but at least reads fault codes etc and allows me to cancel them.

Thanks Alasdair

VCDS Lite, free download from ross-tech.com plus a cheap generic KKL cable works for most stuff on mk1 Fabia, and even mk2 up to early 2010.

Was thinking the same but I reckon I will need full VCDS as I have Mk1 fabia, 2 x MK2 octavia plus a Seat altea xl. Is there anything thats good for all cars as I also have Mk1 Mazda MX5 and Toyota lucida(previa) and my daughter seems to be adding to her collection as well althouh most of hers are older 80's and 90's Have been meaning to put a post up to see whats a general good scanner that would cover most.

Alasdair

A mk 1 Mazda Mx5 won't have an Obd connector but it does have basic on board diagnostics via a socket under the bonnet that can be read by a home made LED or one of these https://mx5tech.co.uk/diagnostic-tool

10 hours ago, skomaz said:

A mk 1 Mazda Mx5 won't have an Obd connector but it does have basic on board diagnostics via a socket under the bonnet that can be read by a home made LED or one of these https://mx5tech.co.uk/diagnostic-tool

Many thanks for the link. Its a project car I was given by a mate who needed it gone ASAP. Its a Jap import eunos 1.8 auto everything solid and all there but no time to start it at moment plus wont turn over due to I think an aftermarket imobilser which I will have to find and try and remove. I assume its similar to the old volvo 940 unit that flashed led codes when you jumped the pins with a paperclip.

Thanks again

Alasdair