996 Turbo Fuel Gauge Empty

Troutman · Dec 12, 2021

My new to me 04 996 Turbo has 1 fault and that is the fuel gauge is reading zero/empty.
I've filled it to full but still nothing. I've disconnected the battery briefly (alarm goes off) and still zero. I've read they do have the quirks but this is not moving , before I claim on the warranty is there anything else I can do?
Car is unbelievable , coming from a Cayman S which was a fantastic car it does not disappoint.

andywill · Dec 12, 2021

Hi
If the tank is full up then odds on it’s a faulty sender unit these are also prone to sticking, If it’s under warranty take it back should be an easy fix. If the tank is empty and you only put a small amount of fuel in because of the design of the tank the gauge may not register the added amount correctly (google is your friend)
Re disconnecting the battery
Switch the ignition on, then off, but do not remove the key, this will prevent the alarm from going off when the battery is disconnected, another tip is to lower the windows slightly to avoid the window catching when opening & closing the door when battery is disconnected.
Good luck
Andy

Troutman · Dec 13, 2021

Thanks , I'll try that again but for a longer period.

tim92gts · Dec 13, 2021

Our '03 Carrera has always taken a while to register, on a part fill it never does.

It often works if filled to the brim but not always.

They say the 4 x 4 s are even worse as there is more of a saddle tank over the prop shaft.

It would be interesting to see what happens if you put a brick under the right wheel when filling.

You can get some idea if you use the trip meter and zero at fillup.

Troutman · Dec 13, 2021

I've tried a long term battery disconnect and no change so it looks like a warranty job

"It would be interesting to see what happens if you put a brick under the right wheel when filling" Yeah I won't be doing that, surely the gauge must have worked when new.

andywill · Dec 13, 2021

The 996 C4 & turbo have a saddle tank, and a 'pocket' at the bottom. The level sensor cannot physically read the fuel in this pocket, and the computer calculates the level remaining. The volume of the pocket is 19 litres, so you have to put at least that amount in the tank before it reaches the level sensor, and the correct level is displayed. Hence, if you do a splash and dash, the level gauge will not show the extra fuel added.

Troutman · Feb 9, 2022

So I removed the sender unit as I was getting no joy and discovered the arm/float was seized/corroded solid as were the metal male fuel unions under the cap. The car had been in storage for many years and therefore moisture in the tank had caused all the metal parts to rust solid.
A new sender was supplied by the dealer I bought it from and I fitted it ...now working perfectly.

Troutman · Feb 10, 2022

I've done a quick video to show what happened
https://youtu.be/MAdhnpx2-_o

The debris in the fuel hose connectors was not crumbled plastic but rust/corrosion from the terminals, they cleaned out well with a cotton bud and looked fine.

Also meant to say the Turbo pump/sender unit is different to the C4 , you have the sender unit, which is only connected to the pump via wires and hoses , the pump sits below it with 2 "outriggers" going to suction ends in the bottom of the 2 lower sections. It's similar but not the same.