AWR-fix: e53 Fuel pump / siphon pump details

[andrewwynn]

Looking closer you may have the three hoses just not installed correctly. The two hoses with green arrows are the siphon output the other is the pressure relief valve (if that fails the siphon also won't work).

All indications are your pump is crooked or the arm to the float is bent. Try to find a photo of a new pump assembly.

The float arm is not raising high enough so it reads low. Bending such that the float starts lower will fix that. You should get max Ω when you put back in. (Including having the cup fixed. Try that first.


Sent from my iPhone using Tapatalk Pro

[scourtaud23]

Great minds think alike but your vocabulary is better than mine (but its my second language)... I've looked at many pictures and besides the plastic coloring, mine looks right.

I've got a 200miles trip this week end, I'll pull it out again next week when the level is lower and try to take the cup out, once out of the tank, I'm quite sure a heat gun will convince it to get back in shape.

With that done I'll try again, the arm does not seem bent so I'm leaning towards the crooked option.

[scourtaud23]

Do you know how the cup is attached in the fuel tank?

[andrewwynn]

I don't see how the pump can be straight with the cup bent.

320°F or 160°C is perfect for reshaping plastic.

Take the obc readings before and after. You should see a jump in right side. If you don't you should bend the float arm to compensate.

The odd wavering at the top end of the scale makes sense if the end is never reached. Note: you need more than about 30L total or the right side will be empty.

[andrewwynn]

Originally Posted by scourtaud23;

Do you know how the cup is attached in the fuel tank?

I don't. I think it must be press fit.

[scourtaud23]

Thanks for all the help and for being the one person on the internet that understands bmw fuel tanks, you sir are a great gentleman.

I will get back into the tank when there is less fuel and get to the bottom of this, I'm not letting pieces of plastic defeat me. I'll of course report back once I have made progress (or failed).

[andrewwynn]

That holding clip is shown as part of the fuel transfer pump in real oem but I don't see included in any product photos I have a small pry bar that is part of drum brake kit that I would use to pry it off. I'm confident it's a ball and socket snap fit situation. Put some vasoline on your hands before putting on nitrile gloves to fend off the inevitable gas on the hands.


Sent from my iPhone using Tapatalk Pro

[scourtaud23]

Thanks for the tip, I have a feeling its going to be "fun" getting it off.

[scourtaud23]

So, having done around 350km since the fill up, I decided to take out the pump and see if I could get the piece out. After going through the getting the pump out joy, the fuel level was just below this piece.

I tried all I could without risking breaking something, it wouldn't come out. So I resorted to bending it in place, it is quite soft so after a few pressures on it, it seems to be in the right shape and angle (at least as good as I can get it while failing to get it out).



I also found the missing black tube, it was free in the tank, and the ending was just before the pump opening on the roof of the tank. I attached it back in place so it now is as it should. As it was, if it tried to transfer fuel, at least a part of it would not be transfered since it would fall on the flat top.

So now it looks close to as it should :



I should went and filled up as the tank dipped below a quarter this morning but its was pouring with rain with heavy winds so I gave up and decided I'd go another time

Before toying with the pump, Test number 6 read : (the car was not flat, angling to the driver's side)
18.0/ 0.7/ 18.8L
After :
18.3/ 1.1/ 19.4L

I'll go fill up tomorrow (if I get the chance) and see if it made any difference.

[scourtaud23]

So I went to fill up, obviously I failed, its exactly as before. I'll take it out one last time to check in case it has moved but I doubt it.

Before filling up : 13,4L (didn't record each side's value)
After filling up :
52.2/ 22.6/ 74.8L

Is there somewhere in the BMW software where the gauge needs calibration? My thinking is the pump part is not original but the assembly is so maybe someone played with it.