Hi chaps

Anyone tested these or the sender unit.

Yesterday started car to the petrol light coming on and guarge showing empty, filled up in local garage and the gauge is still showing empty + fuel light ( Orange one flashing slowly)

Red central light has does not come back on. Does this indicate problem with instrument gauge or sender unit

 

Did you try knocking on the glass and shouting "wake up" ???

No kidding, it works on my 911.

 

Yes tried that several times - have resigned to the fact thet i will need to take a few bits apart soon?

 

Funny enough went out this morning thinking i would need to remove Sender Unit. However everything was working again. It has sat with a full tank of petrol all week. It must have been the moving bits on Sender unit had got stuck as car was left for some time with almost empty tank.

Best sort of repair is the self fix method!!!

Cheers

 

u have to turn the engine off and it will reset... if i add gas w/ the car on the gauge stays the same

 

Fuel gauge now playing up again, While in for a service they looked through and tested Gauge Plus module which seem to be OK.
Looks like issue is with sender unit.

Porsche have stoped making the 4 pinned sender unit fitted to 964s and only now do a 2 pin model which means you also need a new control unit.

Any suggestions UK for getting older porsche part.

 

The fuel sending unit is a two wire resistance device. It goes between 7ohms and 73 ohms with 73 ohms being full. The input is then sent to a little box that attaches to the sending unit with a clamp. There is a processing board inside and then goes into the wiring harness with 4 pins. I assume that it provides information to the gauge and to the light and has power and ground, but I've not looked at a wiring diagram or measured the box. To test the sending unit, you can remove it and test it with a DVOM and you should get roughly the values I specified.

 

I have the same problem, until now it can be "fixed" by just turning the ignition off and then on again. I am not sure it is a sender until problem with mine as the light around the guage also goes out which would lead me to believe it is a connection to the guage issue.

Please keep posting on what you find out.

 

I need to turn off and on the ignition on the 944, 964 and 928 in order to get an accurate reading. I believe it is the way it works.

 

Maybe the issue is a little confused, I agree that if I fill my car with ignition on the reading is not accurate as the guage does not move correctly, at this point the true reading can be found by turning off and on the ignition as you mention.

The problem here is that at any given time after turning the ignition off and on again the guage can read empty, literally five seconds after showing a "good' reading, at the same time, on my car, the light in the surround of the guage also does not work!

 

Sounds like the instrument doesn't have an earth.

 

It's aiIve! ALIVE I say!

Yes, the thread and the question re how to deal with inaccurate readings
... fuel sensor - how to remove/clean/test/service??
Please and thanks!
Matt

 

99% senders have logic that reacts in a window of time, like 3-7 minutes. That's so you don't see the effects of slosh; otherwise as you accelerated, braked and cornered the gauge would be all over the place. If you leave the sender energized during a fill-up, it will eventually indicate "full" but it will take a few minutes.
For example, the oil tank sender does not have this logic. It jiggles the gauge quite a bit.