One fuel pump, a siphon jet and two fuel level sensor s. Left and right.
I forget which test (cluster) shows the two sensor data individually.
Had a beer yet? LOL.

 

Not yet. It's morning right now and I'm on a good behavior bond anyway (figuratively speaking) at the moment.

So all this is visible from the top of the tank by removing the seat? Is there any common issue you've seen that causes these symptoms?

 

Before you take the back seat out, do the 'troubleshooting menu'
test with the cluster-
it sounds like one of your sensors is stuck at empty, and the test
will tell you that.

THEN pop the back seat, and pull the offending sender. They can stick,
sink or break. DO wait until you've used at least a third of a tank-
the fuel level's higher than the sender when it's absolutely topped- off.

I found that out once.

hth
t

 

Thank you,

Which number cluster tests will show sensor operation? I've gone to the fuel tank levels 19/6, and there's 3 numbers like 337 etc. Is that meant to be 33.7L? How do I tell which reading is left or right sensor and whatnot?

 

Hope I'm not jumping on the OP's thread too much, but it seems relevant.

Hidden menu function 19/6:

6.0 118200-199200. Seems to fluctuate a bit just sitting there.
6.1 351 35.1L?
6.2 329 32.9L?

If this is the case they are both reading correctly (I've just topped it right off)? Would this mean that I should reset the cluster via 19/21?

I would appreciate some advice, as I'm home today and want to have a look.

 

If its not on the cluster i would just pull the sending unit out of the tank, not that big of a job (10mins), i did mine a while back when my pump went out, you can then check the level sensor thingy and make sure it moves up and down without problem...if its the original pump, and you have some money laying about... probably best to replace it as well while in there... Good luck m8

 

I'm not convinced the sending unit is reading wrong, as it appears to be reading full tanks on both sides. I'm hoping resetting the cluster might be all it is, but I'm wondering what else it resets at the same time.

 

OK,

For a full tank are my 6.1/6.2 readings correct? This would suggest the cluster wouldn't it?

One factor I didn't mention was it sat pretty empty with fuel light on for a week while I was away.

 

They say we have a 60 ish litre tank, and if thats divided to the two sides then i would say 30ish each side would mean that the cluster indeed is showing wrong...then again the lift sensor could he stuck...but then again in the secret menus it would also only show a half tank so it has to be the cluster needle showing Wrong...i think....

 

Ok, next, run it down a quarter tank or so, and pull the senders!

It's not hard (cleaning takes longest, as it gets skungy under there)

and then you can physically move the senders and see what the gauge interprets that as.

Yes, it's kinda stinky, and no smoking.

I've just had a DME with a bad eeprom cell, so I'm all about the 'reflash your cluster and see if the problem migrates'
but don't do that yet.

You can also unplug the senders and meter them- I forget the actual values, but you're looking for
smooth movement between something like 60 and 0 ohms for each.

hth

t
wears a respirator these days.
Gas used to smell better.

 

Just because a sensor behaves good or bad at 80% height (it's just a resistance wiper) doesn't mean it not going to fail at another level of fuel.

Keep track of your distance (as to not run dry) and try the above tests at various levels of fuel.

 

You're an intelligent and methodical tester. Easy for you.

 

Well thank you, and now I must live up to your kind words....but seriously, no smoking? What's the world coming to? Next thing you'll be telling me I can't be drunk while I do it.

All jokes aside though, I'm glad you popped in on this one. If the hose clamps are original would I just replace the fuel pump on the right and the sensor on the left and be done with it?

My understanding is that the level sensor is integrated in the pump on the right, and a sensor only on the left. Is that correct? Do you see many of the LH side sensors fail?

I'm running out of time for re rego, and the steering/suspension is the focus. I'm inclined to drive short trips until then and live with it just for a week or 2. Especially if I'm still getting full use of the fuel tanks and can just track my kms to make sure I don't run out.

 

Mate i found this after going around the forum, hope it's of some use.

Fuel filled to the max, but gauge says 1/2 full then...

my e46 330ci, i fill up the petrol to the max, but it only reads half way, however when i start driving for a while it slowly creeps up to 7/8. I then did a cluster reset menu 19.21 and 19.2, and still didnt clear the problem. Then i did a fuel reading test when its full, menu 19.6, and gave...

www.e46fanatics.com

 

Yes it is, thank you.

I will pull the back seat out and have a look. They seem to allude to electrical connections as a potential fault, and it's amazing what can be achieved sometimes with a can of contact cleaner. I'll try that first.

 

It's a soft seal- the only danger is that it's pretty easy to seat incorrectly, and then sometimes it gets damaged.

I've replaced 3 pumps, and while I have a spare seal in the 'spare seal' drawer, I've never had to use it.

Yes, this is a job best done after several tins.

t

 

Given what you state, replacing the pump is a good idea.

The problem with either of the level senders is that they are what we call a "wiper". There's a resistance change on a rheostat type of track. As the float arm rises/falls the amount of resistance back to the cluster (fuel level reporting AND heavily buffered) changes.

It's very possible that the resistance values are good for 80% of the travel and bad in one or two spots?
The only way to know would be to bench test it with a DVOM.

 

Yep, I'm on the same page.

Money's a little tight and I'm on the home stretch for re registration now, but if those hose clamps are original it's coming out.

 

Just to "close this job off" and for anyone who has had the same problem, I fitted a new pump today and all seems good. It wasn't the original pump, as it had a generic hose clamp and signs of the amateurish workmanship of the previous owner, but I changed it and the gasket all the same.

I've only driven a short trip as it's unregistered at the moment, but I'll be interested to see if this doesn't improve my fuel trims.

 

FWIW. Max and min resistance of sender unit.

 

Bit late now as I've fitted the new one, but I'll have a look at the old one "for science".