Fuel tank 65L 320i 1993cabrio

[woods]

Can anyone help or advise why one side of my 65L tank is nearly full with fuel whilst the other side of the tank is empty. Finding out how the fuel is pulled from one side of the tank to the other side is proving difficult!!!

Thanks for any reply
Ian

[Brianmoooore]

There's an internal syphon pipe which transfers fuel from the LH side to the right, and deposits it into the pot that the fuel pump picks up from. The syphon is primed by the fuel returning from the fuel pressure regulator on the engine.

[woods]

Thanks for the info, obviously this is more complicated.

Fuel pressure regulator could well be the culprit!!

Time for further investigation methinks...

Cheers Ian

[Brianmoooore]

What makes you think there's a problem? As long as the fuel pump pick up is kept immersed in fuel, that's all that matters.

[woods]

When checking the fuel sender units (fuel gauge not working) I noticed one side of the tank was empty whilst tank side with pump nearly full.

Long story the car been garaged since 2006 just had mot with cam belt, brakes, oils, plugs etc etc, now running well apart from fuel gauge.........

[Brianmoooore]

Fuel gauge should still read accurately, even if most of the fuel is on one side. There are two electrically identical level sensors on your car, one in each side of the tank.
Pull the three pin plug off of the level sensor on the right hand side, and link all three pins in the plug together with a piece of wire. This should make the low fuel light come on and the gauge go to full when the ignition is switched on.

[woods]

Thanks, I will get back to you.

[woods]

With 3 pins linked together (ignition on) the gauge reading just half full with NO low fuel level light on!

[Brianmoooore]

With 3 pins linked together (ignition on) the gauge reading just half full with NO low fuel level light on!

Sorry, for the second time tonight I've posted without fully engaging brain!
That would work with a 55 litre tank, but for a 62 litre, that's what should happen. It should have read connect them together and earth them.

[woods]

will check tonight and come back to you.....appreciate your help

[woods]

Just checked all 3 terminals to earth with same result gauge half full no low level warning light!

The fuel gauge is correct for 65L tank reads 0 to 60?

[Brianmoooore]

I'm definitely working too hard - need a holiday!!
Right, third time lucky! Earthing the brown/grey on the three pin plug on the RH sender should make the low fuel light come on with the ignition on. Earthing the brown/green in this plug should give a partial reading on the gauge, as it has.
Earthing one of the brown/green wires on the plug of the sensor on the LH side should do absolutely nothing, but earthing the other one should make the gauge read full.
Based on what you've said so far, it looks like either the RH level sender is open circuit (should read about 60 ohms empty and close to zero full) OR you have the wrong gauge in the cluster and less than half a tank of fuel.
I take it your gauge is marked in litres? UK gauges aren't calibrated with any numbers at all, so I've no idea if the 0 - 60 marking indicates the larger tank, or if the smaller tank gauge has different numbers.

[woods]

Take your holiday!
Thx again will check tomoro

[woods]

Earthing the brown /grey on the three pin plug RH sender NO low fuel light! So points the finger to the bulb on the gauge?

Earthing one side of the RH sender the fuel gauge reads FULL, whilst earthing the other side does nothing

I have since replaced the RH sender unit to make sure however same result

could well be a fuel gauge problem as you mention......The gauge has no litre marking only R 10 20 30 40 50 60

[woods]

Sorry got my LH and RH mixed!!!

Meant to say, earthing one side of the LH sender the gauge reads full, whilst the other side does nothing.

[Brianmoooore]

Put the plugs back on both senders, pull them out out of the tank, and turn them upside down.
Gauge should go to full.
Turn one sensor back the right way up, and gauge should go to half.
Turn that sensor upside down again, and the other one back the right way up. Gauge should read half again.
If both tests with one sender upside down result in a reading of zero, then you have a 55 litre gauge fitted.

[woods]

Ok will give it try...thx

[woods]

Hi....got to the next tests
the gauge appears to be working fine with either sender upside down the gauge reads half as you say and not 55lite
I plan to fill the tank full and see what happens both senders appear to work ! Will let you know

[woods]

with a full tank of fuel both senders appear to have corrected themselves with gauge reading fuel
I will live without the low level warning light until next time the instrument cluster is removed.
Thanx for your help and advice