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Fuel tank only filling half way?

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Fuel tank only filling half way?

My 1999 530d manual touring has become progressively more difficult to start the lower it gets on diesel after the low fuel light comes on. So much so that when I am low, I always give it a few seconds with the ignition on until I hear the under floor pump tone change then she starts on the button. This is not necessary with any more than a quarter of a tank of fuel. Its been like this for a couple of years and I can live with it. I have checked all the inner tank pipework and changed the tank pump so can only assume the issue is the left hand venturi jet pump not doing what it should…..?

Recently, I went to fill up after travelling over 550miles since my last fill I could only get 28l in the tank. This was even after taking it slowly and changing the angle/height of the filler nozzle.

I checked no 6 in the hidden menu on the garage forecourt and it showed 33l right and 8l left total 41l. Gauge shows just over half full. So this all seems reasonable. This is now happening every time I fill.

Before I filled this time, I removed access panels and tank access and physically looked in the tank. Almost completely empty on right and some fuel on left. Hidden menu no6 said right 4l and left 9l total 13l. Am I correct in thinking this is a saddle tank lower each side with a link part joining each side like a dog bone. If so, I can’t understand why only one side would fill.

I have tried filling on forecourts at differing angle with no effect. I have searched an seen others with the same half fill problem but could not find a solution.

Any ideas why it now will only fill on the right will be gratefully received.

Sorry this is so long winded.


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I’ve been thinking about this a bit more overnight after looking at the tank part diagram.

It could be air locking as the filler looks to lower than the highest part of the tank where it joins to the left side.

I will check the breather for blockage at the weekend.

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