Technical Dodgy Fuel Gauge

[Monkey79]

Hello all, 1st post here and all that... would have come here sooner had I realised this place existed

I've got a 93 (er.. or 92, I forget... K reg anyway) Tipo 1.4 ie and love her to bits, she's my first car (although don't go assuming I'm some young wee nipper in his teens, only bothered learning to drive a few years ago and I'm 28!)

One of its little quirks that really bugs the crap out of me is the fuel gauge being anything but accurate and prone to bouncing around whilst driving about. The only time it is accurate is for the 5 minutes after filling her all the way up. The needle quite frequently bounces around on empty for days on end aswell, especially when I know I'm running on more than fumes.

I can't seem to find any other mention of the problem online, have any of you guys experienced this and if so, what the hell is causing it? for what it's worth, every other gauge on the dash operates fine and dandy from what I can tell.

Cheers in advance!

(I've got a second question to post in a second or two, hope that's not against the rules but as they're unrelated questions I figure it's best to keep them apart?)

 

[maddogmorg]

mine started to play up not long ago, and i have a funny feeling that it's related to the wiring in the boot being knocked. in most cases its earth faults so just visibly check and wiggle them about and see if that makes a difference.

does it flick from empty to where it should be or just bounce around a bit? and also is the low fuel light coming on at all?

 

[Monkey79]

Yep, the fuel light comes on quite often, either on full or flashing even when the tank is half full and yep, it bounces about but it does return to where it should be on the gauge (before merrily bouncing off again)

It doesn't bounce around much when I'm definitely running low. Just loiters around the empty mark

The best way for me to keep track of my petrol at the moment really is to keep an eye on the mileage, whilst it's not perfect it does give me some indication of how far I can push it.

Edit: Speaking of mileage and all that lark, does anyone know the fuel capacity of the tank on the 1.4ie?

 

[Green]

Fuel capacity is 45l. Btw, a jerking fuel gauge is often caused by a worn variable resistor that floats in ur fuel tank. There is a float that's transferring its motion onto the resistor, and varying the motion as fuel level goes up and down, it varies resistance, which in effect varies your fuel gauge reading.

When they wear out, they become erratic, needle bounces around like mad, low fuel light often lights for no reason etc... It all happens because the film on the resistor is torn and worn down in one or more spots. Mine does it with less then 10 ltrs of fuel in - it seems previous owner got it on reserve most of the time

 

[Monkey79]

Fuel capacity is 45l. Btw, a jerking fuel gauge is often caused by a worn variable resistor that floats in ur fuel tank. There is a float that's transferring its motion onto the resistor, and varying the motion as fuel level goes up and down, it varies resistance, which in effect varies your fuel gauge reading.

When they wear out, they become erratic, needle bounces around like mad, low fuel light often lights for no reason etc... It all happens because the film on the resistor is torn and worn down in one or more spots. Mine does it with less then 10 ltrs of fuel in - it seems previous owner got it on reserve most of the time

Ah, just flicking through the porter manual.... this would be the same thing as the 'fuel gauge sender unit' right? If so, I may have a look into that this weekend when I'm re-united with my car.

Thanks!

Disclaimer: Never really had much reason to go nosing about with the inner workings of a car before but finding myself increasingly interested so excuse my newbie'ish questions

 

[Green]

fuel gauge sender unit - correct!

Take a look, but be warned, no smoking, no open flame, no sparks around fuel! U need to open the fuel tank from inside before u can take a look. And its compulsory that u disconnect the battery at least 1/2 h before u get to work. BOTH positive and negative leads. No power - no sparks.

Lift trunk doors. Empty garbage from trunk (or not, depending what u have in
there), I had to do this step Then lift carpet, remove it. Just beside the spare tire there is a plastic cap, usually round or slightly oval. Pry it up with a
flatheaded screwdriver, it sometimes sticks pretty strong, just watch it not to chip the paint. Then u can disconnect fuel lines and wiring, and dismount the sender unit and pull it out. Then as for the inspection, u will usually see where it has scratches on gliding surfaces, it means its worn. Only means of repairing it is to replace... I have one spare, circle type.. They can be round as a circle, or oval.. depending on tank. Not interchangeable, must be replaced with same type as original...

Oh yes-fuel hose n clamps...pretty sure they're original, ull have to break the clamps off with a pair of pliers to get em off.. need to have spare clamps, screw-type and some hose handy... and be careful when getting old clamps down, underneath the sender is brittle plastic, it easily shatters, and if u wish to reuse it, u wouldnt want that...

On second thoughts, one more thing..there also needs to be a small gasket between the sender and the fuel tank - not sure if it can be reused...if is starts smelling like fuel and a little spill on hard corners after reasembly, then it cant be reused...

Everyone started somewhere, right? There was also a time when I had no idea abou cars, it was a very long time ago....but it was When u get into cars, ull never be cheated by a tech again at a garage - a very good advantage btw!

 

[850kd]

I once had a fuel guage like that, and it turned out to be a loose baffle in the tank, which in turn fouled the float. The car was a Strada II (Ritmo) which had , i believe, a metal tank. I cant remember if the Tipo has a plastic tank, if so then this will not be relevant , but just a thought.

 

[Green]

Yep, Tipo has a plastic tank! no problems with corrosion or anything similar