[Timk22]

Hi guys, been a long time consumer/lurker but this is my first time posting.

I've got an e46 compact (325ti) and I love it, save for one annoying recurring issue. The left side fuel level sender keeps snapping and killing my fuel gauge. I've had the car for just over a year and already replaced it twice (once secondhand eBay, once genuine new BMW) but it keeps snapping in the same place. I'm a bit lost as the part is hard to come by and not cheap. This latest one last 4 months.

Is there something I should be concerned about considering how often I've had to replace it?

 

[tommy d]

You should be using the VDO Fuel pump assembly, anything else, and you will have issues as you described.

 

[TobyB]

Genuine BMW shouldn't do that.
Hell, even URO shouldn't do that.

And that's a really odd fault. As in, 'they don't do that'.
Except that yours did.

Are you sure the part number is right for the compact?
I have the previous gen, and lots of parts for the
different body style have been 'superseded' to the
sedan- and don't quite work.

Otherwise, I'd be looking for something mechanical in the
way the sender seats into the tank. Perhaps even
too- short wires that are stressing the sender?
There shouldn't be ANYTHING going on that can
break that ceramic- the stuff's pretty tough against all
comers- except impact.

You don't have a sea mine in your fuel tank, do you?

heh


t
would LOVE an E46 B30 compact...
...but the Yoo Ess didn't get 'em. Too cool
The cars, that is.

 

[paraklas]

Check the fuel tank from below, maybe there's a dent causing the bottom part of the sender to touch against and break it.

 

[yjsaabman]

I agree with the above. As long as you're sure it's the correct part, something is not right with the fitment I to the tank. Maybe it's not seating in a notch correctly, maybe a piece of an old one is stuck, or maybe the tank is deformed.

 

[Timk22]

Thanks for the replies!

I can't be 100% certain, but I'm pretty sure there isn't a land mine in there! Hahahaha!

There almost certainly is at least one piece of old level sender in there still. I never fished them out...

I've double checked on realoem (RealOEM.com - Online BMW Parts Catalog) and it's the right part number for what I ordered from BMW.

I've not been able to check underneath as yet, but will a look at some point to check for damage!

 

[NZ00Z3]

The Z3's (E36/7) have a habit of breaking the sender ceramic. It's due to sideways mechanical forces acting on the float. For the Z3, its vacuum in the tank pulling the side in. It's a tall thin vertical tank. The E46 tank is flat, so it's not likely the tank sides, unless you have installed the pump with the float pointing towards a side or something like that. Remember that the E46 tank has a hump in the middle that goes over the drive shaft.

 

[Timk22]

The Z3's (E36/7) have a habit of breaking the sender ceramic. It's due to sideways mechanical forces acting on the float. For the Z3, its vacuum in the tank pulling the side in. It's a tall thin vertical tank. The E46 tank is flat, so it's not likely the tank sides, unless you have installed the pump with the float pointing towards a side or something like that. Remember that the E46 tank has a hump in the middle that goes over the drive shaft.

The part isn't ceramic, it's all plastic (even the Genuine BMW one). I thought the original and secondhand failures were due to the plastic going brittle with age and being submerged in fuel for 10+ years, but then a genuine new one failed in the same way after 4 months. The E46 tank is flat, with the hump over the driveshaft. There are 2 sender units, one on the left which is just the float with a PCB attached to a sucking jet pump and then one on the right which is the integrated fuel pump assembly.

It's the one on the left that keeps snapping on me. I've got another secondhand unit arriving this week, complete with the sucking jet pump assembly, so will study that a bit more before fitting it and try to work out what's going on.

 

[NZ00Z3]

I've got another secondhand unit arriving this week, complete with the sucking jet pump assembly, so will study that a bit more before fitting it and try to work out what's going on.

You're onto it. It a mechanical failure, so critical observation of the float's action and running location is required.

 

[Timk22]

Fitted the new part, had a good poke around the tank and fished out the bits of broken PCB. I found a divot in the bottom of the tank where I feel like the bottom 'finger' part of the sender sort of sits in and the spring gets depressed to sort the level.



I'm maybe thinking that the previous ones weren't seated properly in that divot and I maybe forced the top in to place too which potentially snapped the bottom part. I was a lot more gentle this time around when seating it finally. Fingers crossed it lasts a little longer this time around!

 

[Timk22]

So....thread resurrection. The sender that I fitted has broken. Fuel gauge has stopped working again. Really running out of ideas. There has to be something wrong which is causing this part to break so frequently. I'm really confused as the lower part is spring loaded, so I would've thought it would be pretty protected against breakage...

 

[TobyB]

This is, sadly, one of those things where we really have to have the car in front
of us to figure it out. The factory answer would be to simply replace the fuel
tank, but that's silly. You've inspected the underside, and the tank's not
obviously deformed, so it really does have to be something super-
odd with the way the sender's fitting.
And breaking that ceramic takes a shock or a LOT of pressure.

In this modern day of tiny cameras, I might be tempted to take a
broken housing, drill a hole into it, and mount it up.
Then run a camera into the tank and see if it'd show what the hell's
going on in there.

t
out of internet ideas

 

[Timk22]

Thanks Tony, I'll get underneath and have another proper look at the tank to inspect for damage again. Very temped to get an inspection camera down there to see what position the bottom part of the sender is in before taking it out. Might give me a clue as to what is causing the issue. Also going to check for problems with EVAP whilst I'm at it.

The design of the part seems pretty weird. The lower plastic part is spring loaded and there's a ball bearing at the bottom of the 'finger' extension. I would assume it is spring loaded to account for different depths between the mouting seal and whatever it locates to at the bottom of the tank, but from my initial fumblings the only thing I could find for the finger to locate to was a small divot or bump in the bottom of the tank. Nothing secure or anything like that, just a small bump. No idea if that is how it is meant to be seated.