Cheap solution fuel gauge problems

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Raphale
Joined: Thu 05 Nov, 2015 07:48
Posts: 6

  Z3 roadster 1.9

Cheap solution fuel gauge problems

Post by Raphale »

My first post here, Allow me to help UK Z3 drivers !

A wellknown and notorious Z3 bug is a failing fuel meter. (Needle on empty, amber light on while tank is filled)
This can be the result of a dirty or broken ceramic plate located in the fuel sender unit. Under certain circumstances it can be fixed by cleaning the plate, but often it breaks as a result of issues with the tank breathing system creating vacuum in the tank, collapsing the tank and breaking the little ceramic plate. Both tank breather valve and active charcoal filter should be replaced when this happends. On USA, French, German amd Dutch Z3 forums loads of topics on this specific bug. A little less here.
Until now buying a complete new fuel sender unit (pump + level sensor) was the only remedy, cost for the part alone around 300€. For the Dutch Z3 forum we arranged a car electronics factory to make the white ceramic resistor plate only. It was quit a costly , lengthty and complicated process but after some thorough testing and patience we succeeded.
If in the nearby future anyone encounters this problem, you can sent me a PM. It is selling on ebay as well. Costs for the breaking part are only 20€ shipped worldwide. We have some left. Hopefully we can help fellow Z3 drivers with this and compensate the costst and efforts for this project.

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Last edited by Raphale on Wed 18 Nov, 2015 12:37, edited 1 time in total.

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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
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Re: Cheap solution fuel gauge problems

Post by BladeRunner919 »

Can you post a link to the ebay sale?

Raphale
Joined: Thu 05 Nov, 2015 07:48
Posts: 6

  Z3 roadster 1.9

Re: Cheap solution fuel gauge problems

Post by Raphale »

I'm not sure if that is allowed , but if you search for 8896039/013 you will find it immediately.
Price on ebay is higher (paypal, ebay fees)

Raphale
Joined: Thu 05 Nov, 2015 07:48
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  Z3 roadster 1.9

Re: Cheap solution fuel gauge problems

Post by Raphale »

We ordered a few more with the Dutch forum, remaining stock on ebay in case you have fuel gauge problems.
(Needle reading empty with full tank or “dancing” fuel needle)

Bmw Z3 Fuelpump fuel level sensor REPAIR 16141183687 16146756323 Tankgeber http://r.ebay.com/eSZi44

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Southernboy
Joined: Thu 07 Oct, 2010 12:39
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Location: Johannesburg

Re: Cheap solution fuel gauge problems

Post by Southernboy »

Thanks for your post and eBay listing... Just ordered one. :D
Barry
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BonBon
Joined: Tue 08 Jan, 2008 21:10
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Re: Cheap solution fuel gauge problems

Post by BonBon »

The mechanism of the collapsed tank breaking the ceramic plate discussed in detail:
https://www.bimmerfest.com/threads/1997 ... 422/page-3

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Southernboy
Joined: Thu 07 Oct, 2010 12:39
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Location: Johannesburg

Re: Cheap solution fuel gauge problems

Post by Southernboy »

The problem of the broken ceramic card.
First off is to remove the fuel pump unit. Once out,you will notice that the float arm swivels on a plastic tapered pin which passes through a plastic housing.
Gently move the arm back and forth to check the amount of play in the pin / housing. It is likely it is quite a lot due to 20 plus years of wear.
This excessive play allows the float arm to move abruptly back and forth as you drive and the fuel in the tank splashes about. It is this issue which causes the 2 contacts to hammer into the ceramic card and break it.
1. The fix.
Remove the float arm from its hinge / housing. Be very careful not to damage the 2 contacts.
I happened to purchase a can of Milo at some point, and under the plastic lid, the can is sealed with a tear off lid made of very tin but stout aluminium foil material. It just happens to also be the perfect thickness and strength to fashion a shim to fit around the float arm pin.
The tricky part is to get it the right shape because the pin is a tapered/conical shape. But with a sharp blade and some trial an error you can do it. The two meeting edges of the shim once wrapped around the tapered pin should not overlap, but the shim must fit snugly around it.
Fit a new ceramic card taking note from the old one which way up it must fit.
Now re- assemble the float arm to the rest of the pump with your new shim.
2. Checking the float arm for free movement in the tank.
The fuel tank is a plastic container, which may distort over time. It is perversely designed so that the float and it's arm must pass between to walls of the tank which are possibly not more than 100 mm apart. To do this you will need a length of aprox 3 - 4 feet of thin, strong fishing line. ( Just pop into sports store and ask for a short piece - I did and got it for free).
Remove the fuel filler cap and use a screw driver or similar to hold the little sprung door at the top open while you feed the fishing line down into the tank. Then from inside the car, put your hand into the tank through the hole where the fuel pump is fitted, find the fishing line and draw it out and fasten it around the float arm or the float itself. Make sure it is secure and will not slide off etc.
Now put the fuel pump back into position as it would be if it had been completely re-fitted into the tank. It is important to ensure it is at the correct orientation as per the marks on the tank.
Now, go back out and gently pull the fishing line at the fuel filler pipe, and make sure the float arm moves freely without touching the sides of the tank inside.
If it does, you are now faced with a "guess" as to which wall of the tank it is touching. But 1st very slightly bend the float arm towards the front of the car and perform the fish line test. If it is catching worse than before, you know what to do. Once you have made the required adjustment (if needed) you can remove the fish line and refit the fuel pump.

Job done !!
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BonBon
Joined: Tue 08 Jan, 2008 21:10
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Re: Cheap solution fuel gauge problems

Post by BonBon »

How goes friend. We'll keep this site alive as it has so much info.
Anyway I finally figured out - cuz my second one failed after 6 years....
The failure is the fuel breather valve. It creates vacuum in the tank which collapses the wall of the tank on the sender unit. This explains the scratches on the inside rear wall of the tank that are opposite the sender. When it collapses it can either crack the ceramic rheostat board or bend the lever arm.
Just to confirm - I noticed yesterday that the gauge started to fail and when I went to fill up I had the lowest vac ever. My guess is that the ceramic broke....
I am now looking at a way to get rid of this system to make sure it does not happen again (OK it'll release a few fumes to the environment.... which may be better than turfing full sender unit where the plastic never deteriorates...)
An even better solution would be a vented fuel cap - so no vacuum is created. But never saw this recommended before... am I missing something?
I'm thinking this one will fit snugly:
https://www.ebay.co.uk/itm/Stainless-St ... SweuxWRMm1
BTW - are ceramic plates still for sale somewhere?

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Southernboy
Joined: Thu 07 Oct, 2010 12:39
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Location: Johannesburg

Re: Cheap solution fuel gauge problems

Post by Southernboy »

Hi buddy..
Considering the problem, I would simply drill a 0.5mm hole in the cap. It will be more than adequate to avoid the vacuum issue.
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BonBon
Joined: Tue 08 Jan, 2008 21:10
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Re: Cheap solution fuel gauge problems

Post by BonBon »

But without the one-way-valve there will be a smell of fumes. Especially in hot climates.
I ordered the part linked above. I'm also fed up with taking the key to fill up. Hope it fits - only $18 shipped :)
Shame so many thousands of gauges have gone over the years - pissed I did not figure this our earlier.... some people have changed a few until they replaced the active charcoal filter and the breather valve.

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BonBon
Joined: Tue 08 Jan, 2008 21:10
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Re: Cheap solution fuel gauge problems

Post by BonBon »

Quoting you:
"Fit a new ceramic card...."
Are there any still about for sale?
Last edited by BonBon on Wed 11 Nov, 2020 16:33, edited 1 time in total.

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Southernboy
Joined: Thu 07 Oct, 2010 12:39
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Re: Cheap solution fuel gauge problems

Post by Southernboy »

They were on eBay quite recently
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BonBon
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Re: Cheap solution fuel gauge problems

Post by BonBon »

The Dutch guy seems to be out of stock. Wanted a spare in case....

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Southernboy
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Re: Cheap solution fuel gauge problems

Post by Southernboy »

Oh dear... he's the only guy I know of who sells them.
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BonBon
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Re: Cheap solution fuel gauge problems

Post by BonBon »

There will be a new batch in January :squeeze:

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Southernboy
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Re: Cheap solution fuel gauge problems

Post by Southernboy »

Might be a good idea to get a few... other people will surely need some in future.
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BonBon
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Re: Cheap solution fuel gauge problems

Post by BonBon »

Perhaps not, if they get vented fuel caps 😅

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Southernboy
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Re: Cheap solution fuel gauge problems

Post by Southernboy »

That will only happen after the fact.. guaranteed. :lol: :lol: :lol:
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Bertie
Joined: Sun 06 Oct, 2019 03:46
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Location: Montreal Canada

Re: Cheap solution fuel gauge problems

Post by Bertie »

A vented fuel cap would have the same effect as a loose fuel cap ?? A loose cap provoked an engine warning light on my
2001 Z 3.0i , and a buttock clenching ride home as I assumed the little red light predicted imminent engine failure

Bertie. .

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BonBon
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Re: Cheap solution fuel gauge problems

Post by BonBon »

I can confirm that the cause of my collapsed tank was a failed release valve.
For now I opened the pipe going to the activated charcoal filter from the tank and no light has come on (so far). So hoping the vented cap will work.

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BonBon
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Re: Cheap solution fuel gauge problems

Post by BonBon »

What now?
I opened the tank and found the ceramic plate in tact - but the lever arm in its plastic housing was out of place. I cleaned the ceramic plate the bent the arm to be in its correct position and put the lever and housing into place. When turning the switch it read correctly, "almost empty" and when I filled up it also read "full tank".
But now it is jumping from open circuit (ie guage at wall to left with fuel warning on) to full tank every 10-60 seconds.
Any ideas?
My only guess is either a bad contact where the wire is at its last leg - or a non conducting layer on the tips of the spring loaded contacts. I read somewhere that there is are improved "gold system" sensors but I have not found them yet....

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Southernboy
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Re: Cheap solution fuel gauge problems

Post by Southernboy »

I think you may have missed the problem.
That arm as you will know now, cannot be bent very easily. It's very strong.
So, I would remove the pump again, and check the the plastic housing to which it is attached, has been clipped in properly.
There are 2 points where it clips onto the main body. They are prone to distorting and sometimes even breaking.
I used two very small micro screws - self tapping to secure it to the main body on my pump. Now I know it isn't going to un-clip itself.
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BonBon
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Re: Cheap solution fuel gauge problems

Post by BonBon »

I know I put in place properly - with the two clamps you mentioned. I’ll see when I open up again whether it unclipped.
But my bet is on a bad electrical contact between one of the spring loaded contacts and the ceramic plate. I cleaned the plate - but I should have also cleaned the 2 contacts.
As I need to wait for the tank to empty - I’ll get a pretty good idea which it is. If the reading is correct when there is contact - I’ll know it’s an electrical issue and not mechanical.
Either way it’ll go back it with a couple of screws ;-)

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BonBon
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Re: Cheap solution fuel gauge problems

Post by BonBon »

Not only was there erratic contact at full tank - the readings were a bit incorrect as the tank emptied.
Removed the unit and the problem was bad contact between the contacts and the Ceramic at full tank position (and presumably error prone readings the whole range) .
Anyway, I took an arm and a Ceramic plate from another unit and all seems well.
I still have another mystery. Why doesn't the fuel gauge work when I tried to test it outside the tank with just the connector ...... raising the lever did not register on the fuel gauge. :shrug
When I put it all back together in place it is now OK.

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