Hi guys 

Just wondering if you could help me out, my fuel gauge reads backwards just wondering how I fix this, do I reverse the polarity on the gauge or what?

Any advice would be appreciated 

Thanks in advance

Sounds very odd - If you fill up, do you have a low fuel alarm as well ?

Wow that's a weird one!

I think the issue will either be the cluster itself or the lift pump in the tank... I believe the cluster only has 1 signal wire from the tank giving it it's fuel level. 

For pre 2000, Haynes shows pump, gauge and low level switch all in one unit, with a common earth E3 ("Rear End, LHS"), with two black cables from the tank.  Three other cables going to inertia switch, Gauge and aux warning module.

If E3 has a high resistance, motor and/or low level switch may provide a "back feed" to gauge, just like a poor earth on a rear light fitting gives the back of a car that "Fairy Lights" look!

Sierras used to have a 5V regulator for Fuel and Temperature Gauges, whether a 1999 Fiesta has one is anybody's guess....

sorry about the very late response lol (three years) @Paulkp yes if I fill up the fuel light comes on and if its empty it shows as full not entirely sure what to do.

Just wondering should I maybe try and put a new sender in the tank

Well clearly not a very important issue for you since it took 3 years for you to check back to see if there was an answer 🤣

 

Tbh i have had medical issues so i had to stop driving so I just haven't even bothered looking at it but things are in a better position now so just looking for some advice on how to fix this please

 

1 minute ago, Birdy132 said:

Tbh i have had medical issues so i had to stop driving so I just haven't even bothered looking at it but things are in a better position now so just looking for some advice on how to fix this please

Totally unrelated to the car issue, but how have you found getting back into driving?  I've been 'off the road' due to health issues for the past 18 months myself.  Been looking for any advice online about how to safely get back OTR now but there doesn't seem to much about.

I have epilepsy so i had to stop driving for a minimum of 1 year until i stopped having seizures

6 minutes ago, Birdy132 said:

I have epilepsy so i had to stop driving for a minimum of 1 year until i stopped having seizures

Good to hear the seizures have stopped for now.  Have you tried driving again recently or just preparing the car for when you can? 

I seem to have kept the muscle memory for physical driving, but visually it feels very weird, particularly depth perception.  That said, I did manage a few yards in the car park yesterday, as well as a precision bay park, though I think that was probably more luck than judgement!

good to hear mate, dont suppose you have any advice on this fuel gauge issue i'm having😁

1 hour ago, Birdy132 said:

good to hear mate, dont suppose you have any advice on this fuel gauge issue i'm having😁

Lol, Mk4s aren't really my area unfortunately.  Personally I'd lift up the rear seat to see if you can access the fuel sender plug.  If you can access it, then work out which pins are for the fuel gauge.  Then unplug and add a couple of short link wires between the plug and the pump pins, crossing them over to reverse the polarity.  Switch the ignition on and see if the gauge works.  (Pump won't run like that so don't attempt to start the engine).  If reversing the polarity works, then I'd just cut the wires and cross them over.

No idea how the polarity would have accidentally switched but that's the best I can offer without any specific Mk4 experience.

Nice one thank you mate, I'll give that a go failing that ill just order one a sender from work

Good to hear you are getting back in the saddle.

Looking at Haynes, it states that the tank has to come out to access the fuel sender/pump assembly, so that will be a bit of a palaver involving draining the tank etc.

Exactly what model/engine do you have ?

Haynes shows different connections either side of Feb 2000, with the earlier having a five pin connector with all cores used, and later, with only four cores used.  Have you been able to check the earth connection ?

I haven't tbh mate but i did have a look before i came and asked for help on here and the previous owner has cut a hole under the osr seat to access the pump so I'm thinking is it possible that they have just fitted the wrong pump if there is multiple options engine code code is DHA ztec dohc 1.25s

CatCar lists three different Sender and Pump assemblies with warning light, and two different cable assemblies, so it sounds as though there is a good chance that an incorrect part has been fitted.

Nice one cheers mate, since I work at euro car parts I'll try and get one from there, I even asked the lads at work and they where like wtf and didn't know what to do to try and help