Fuel Gauge error?

[TWO]

The fuel gauge on start up was reading quarter full..........while driving the gauge started to creep up and settled on half full (dead central).

To be safe; I re-fuelled with 25 litres, and the gauge now reads 100% full.

Is there an easy way of checking if or where the problem may be occurring?

Cheers

 

[BMBabe]

Oh that sounds very odd
Hopefully the tech Zedders will know how to sort

 

[Jack Ratt]

The tank holds 51 litres if my memory serves me correctly so 25 litres into a half full tank will give you a full tank.

 

[Redline]

What you didn't say is if the 25L you put actually filled it to the brim. I presume so, which means it was under-reading when you started the car.
Was your car parked level?
Is it the first time it's done this?

 

[TWO]

What you didn't say is if the 25L you put actually filled it to the brim. I presume so, which means it was under-reading when you started the car.
Was your car parked level?
Is it the first time it's done this?

Hi Redline

Many thanks for the response.

No, the 25L did not fill to the brim..............the car is always parked level when starting................Yes, this is the first time it's done this.

I thought it was strange that on start up the car normally gives a true reading...............I've never seen a needle increase in fuel as you travel......it's always the other way

The question still is : - Is there an easy way of checking if or where the problem may be occurring?...............is it a fuel tank out job?

 

[Redline]

Hi Redline

Many thanks for the response.

No, the 25L did not fill to the brim..............the car is always parked level when starting................Yes, this is the first time it's done this.

I thought it was strange that on start up the car normally gives a true reading...............I've never seen a needle increase in fuel as you travel......it's always the other way

The question still is : - Is there an easy way of checking if or where the problem may be occurring?...............is it a fuel tank out job?

Just try to determine the conditions under which it did this to be sure it just wasn't the initial conditions.

It sounds like the fuel sender in the tank. They normally read empty when full when they fail so its a little odd that it goes the other way.
Having just said that, I've just seen a post saying the Z3 has two senders because of the shape of the fuel tank sitting over the driveshaft. If one side is faulty it could give the kind of effect you've had. If one side goes s/c it reads empty and pulls down the average reading on the gauge. Maybe a bump caused it to be OK again and the reading settled to its true reading.

I'm hypothesising to be honest but I'm sure a Z3 expert will be along shortly.

 

[Stevo7682]

I've not had my zed long but am a mechanic .
Someone hopefully can confirm this behind the drivers seat is a cut out in the carpet (I'm not with the zed just now so doing this from memory ) behind that is a seal if you take that out the fuel pump level sensor in there so tank should not have to come out a look on real OEM seems to confirm this being where it is . Don't know what involved in remove and test from there having never done it. If you do remove it need to run fuel down a bit first.

 

[Redline]

I've not had my zed long but am a mechanic .
Someone hopefully can confirm this behind the drivers seat is a cut out in the carpet (I'm not with the zed just now so doing this from memory ) behind that is a seal if you take that out the fuel pump level sensor in there so tank should not have to come out a look on real OEM seems to confirm this being where it is . Don't know what involved in remove and test from there having never done it. If you do remove it need to run fuel down a bit first.

There is a post by @spurs fan in a coupe somewhere on here that tells you how to do it. I saw it earlier and meant to add the link. Out walking the dog at the moment - will goback and add it if no one has found it by the time I get back.

 

[spurs fan in a coupe]

https://zroadster.org/articles/bmw-z3-fuel-sender-unit-removal-fix-your-faulty-fuel-guage.48/

Cheers

I have a used one for sale if you need it?

 

[Brian H]

The fuel sender in the Z is prone to erratic readings, @TWO what fuel do you use? It is thought that the cheaper fuel puts a coating on the contacts of the fuel sender unit this then gives erratic readings.

Put through a couple of tanks of premium fuel and see if it makes a difference?

 

[TWO]

The fuel sender in the Z is prone to erratic readings, @TWO what fuel do you use? It is thought that the cheaper fuel puts a coating on the contacts of the fuel sender unit this then gives erratic readings.

Put through a couple of tanks of premium fuel and see if it makes a difference?

Hi Brian

Since I've had the Zed (5 years), its only ever run on Shell or BP Premium...........that's why the wife calls it the 'mistress'

One thing I will admit to...........the Zed had been standing for 4 weeks...............but this is the first time I'd seen any thing wrong with the fuel gauge.

The Zed is out and about for the next week so I'm hoping that it it's a 'one off' problem.

Thanks everyone for their comments and advise

 

[Redline]

Hi Brian

Since I've had the Zed (5 years), its only ever run on Shell or BP Premium...........that's why the wife calls it the 'mistress'

One thing I will admit to...........the Zed had been standing for 4 weeks...............but this is the first time I'd seen any thing wrong with the fuel gauge.

The Zed is out and about for the next week so I'm hoping that it it's a 'one off' problem.

Thanks everyone for their comments and advise

I don't think you'll see it again while your using it regularly. Sounds like one of the senders was dodgy until it was freed and everything returned to normal.