tokoro

I just have the same problem light blinks a lot and no fuel level sign just marking empty, I get the sending unit out of the tank and clean it nothing happen, i bought a new one nothing happen!!!! what can I do?
HELP!!

HiWind

hey tokoro

did you clean the contacts?

as jason said above ...

If cleaning the pin contacts on the sender and the back of the fuel gauge doesn't work, as a last resort the procedure for checking the fuel tank sender unit with a multimeter is;

1. Hold sender unit vertically, with the threaded flange pointing up:

Reading: 70.1 Ohms to 74.7 Ohms

2. Turn sender unit over; threaded flange points down.

Reading: 1.1 Ohms to 2.5 Ohms

You want to flip the sender unit over rapidly and read the resistance immediately after the float has audibly bottomed out. The one problem with removing the sender unit is Porsche recommends that you DON'T reuse the sealing ring and to coat the new one with an acid-proof grease. The tightening torque on the sender unit is 30Nm (22 ft lbs.)

If all that works .... start testing guages.

ps - where are you?

tokoro

Thanks for reply

The sending unit the tube that goes inside the tank is new but if the gas light turns on i think there is no problem contact with what can i clean that? contact cleaner?

Im in puerto rico

Regards

hamah

Love these DIY fixes and by extension this forum and community. Even when the fixes don't always go as you hope (my recent cab top latch motor gear being a prime example) it's always a lot of fun to work on the car. You learn a lot.

tokoro

I think i found the problem
the control unit!!!! i bought a new sending unit when it was good!!! ((

HiWind

That looks like it!

tokoro

yes if you see control unit the case, it is with holes in the upper part and no hole In the lower, mistakenly water get into those holes the board get wet and water stay inside.
I suggest to verify it.
the 993 they change the location

tokoro

The acid proof greaseis the same use in batteries??

HiWind

just bumping this after reading something in Adrian's book - the low fuel light can also be triggered by an empty windscreen washer bottle - anyone had that experience?

HiWind

This is what my sender looks like inside ... No float, just insulated copper ribbon ... Odd!










Maybe works with temperature i.e. Fuel cools?

HiWind

bump for some input from the less electrically challenged please!

klr10

They work on capacitance, google Capacitive Fluid Level Sensor.

HiWind

thanks Klr ... yes see that ... so it is temperature of the fluid and there is no float etc..?

klr10

It uses the thin wires as electrodes of a capacitor and constantly measures their ability to hold a charge (probably with a microcontroller). As the fluid engulfs more of the area surrounding the electrodes this ability decreases giving an indication of level.

HiWind

awesome thanks! ... was properly puzzled ... can you give me a guide to testing it?
i get a reading of 1224 on two of the pins and 974 on the same top left one and the other bottom one but it doesnt change despite being submerged in water ... how much current do i have to inbtroduce?