Replaced both Fuel Level Sensor/Sending Units. DIY with pics....

Nice right up Thank You, did the fuel pump only toom 30 minutes thanks to you. Found the VDO at autohauz AZ for 145 w free shipping.

why not call the sending unit fuel gauge unit or something? because that all it does is register fuel and trigger light for low fuel

Thanks for this excellent write up. My 01 325i has been having issues dying at stop lights, dying when I barely give it any throttle to take off to finally last night acting like there was no power when pressing the gas. After pulling off the side of the road, it would then try to start then sputter and die. Towed it home and this AM cleaned the MAF and replaced all the plugs and still no start. I then tapped on the fuel pump and it started!

Time for the replacement now!

this might be a stupid question but what is the function of fuel sending unit? does it sucks fuel from one side of the tank to its own side? How to check if they are bad or not. And what about the fuel pump with sending units, i have seen those too. Thanks

Originally Posted by vitaladeel

this might be a stupid question but what is the function of fuel sending unit? does it sucks fuel from one side of the tank to its own side? How to check if they are bad or not. And what about the fuel pump with sending units, i have seen those too. Thanks

Check johnnatalie's post above. I believe that is the answer. The fuel sending unit is really a fuel gauge to tell you when the fuel is low. I'm not sure why there are two of them (one on each side). If you buy a new fuel pump, it should have integrated into it a "fuel sending unit". Someone correct me if I'm wrong (which happens frequently).

I just replaced my fuel pump last night. Thanks to this write-up, it was honestly a 20-30 minute job. Here is my only bit of advice. When I disconnected the fuel line from the pump, it had some built up pressure and sprayed a bit on my back seat. There wasn't a lot of fuel, but the pressure made it spray everywhere. Sprayed worse when I tried to put my thumb on it. I would recommend wrapping the connection in a rag so that when you disconnect the fuel line, it sprays into the rag.

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After you installed the new fuel pump what was your psi on the rail?

great write up. I used your DIY to change out my fuel pump today. the only bad thing I did wa I resused the hose clamp and pump gasket. I ordered the gasket and hose clamp but it did not arrive yet (different shipment from my fuel pump) Drove around the for 100 miles without the rear seats and the metal plates (w/ 10mm bolts) and did not see or smell any fuel leaks so I guess I am good to go.

Great DIY! Thanks OP and everyone.

after running out of gas on the freeway at night and once in my garage, i thought my car was just retarded....apparently when these sensors go bad, 1/4 of a tank means dead empty....need to do this soon....or just keep my car above 1/4 tank....lol

I have had similar issues to all the above (stalling, cutting out and running out of fuel with fuel still in the tank) with the exception of the rough idle which I haven't had. One added bonus is the liters used per 100km (Australian car) shown on the computer is currently showing 0.8 it should display something like 11.4. The problem is when I took it to my mechanic the only codes its throwing are EWS tamper codes. I had a couple of after market keys and my EWS reprogrammed a year ago so I am not surprised there are codes but I don't think this is the true issue as that was done over a year ago and the stalling and running out of petrol have been issues since day one well before I got the keys done.

So my question is: is there anyway you can test whether or not the fuel pump is working and the same for the sender as they are not exactly cheap? Also the filter was replaced in last years service should I replace it again.

Any help would be much appreciated.

Sorry another question. On RealOEM there is another part called a sucking jet pump part no 16146755880. Does anybody know if you need this?

I have this problem on my 04 M3. However, no loss of power or stuttering as long as I'm above ~1/4 tank. I checked the cluster info, and it stated that there is plenty of fuel in the driver side tank but the passenger side tank, where the fuel pump is, was empty. So what exactly transfers the fuel from driver side to passenger? The fuel sending unit I presume? Am I right that the fuel sending unit is both a sensor and a small pump?

16116768788 -- this should be all I need right?

ECS calls it just a sensor, is this a pump as well?
ECS LINK

Just wanted to double check that I don't also need a fuel pump. Thx guys.

As far as I know, the "Sucking Jet Pump" (also called siphon pump) part #3 in second chart link below is the part that sends fuel from the left side (driver) to the right side (passenger). The right side unit part # 1 is the main fuel pump (called Delivery unit) that feeds fuel to the engine. The left unit is just a fuel level sensor (also called fuel gauge sending unit, part #2).

Note added: The siphon pump (part #3) is actually not an electrical pump. It has two hoses, one connects to an adapter on the left level sensor, and the other runs all the way to the right main pump and goes through the tray under it. So the siphon (pumping) action from the left tank to the right is related to all three parts. I believe the main suction action is created from the main pump (at least in my case), but also requires that the siphon pump is not clogged (rarely happens), and that the siphon pump is still connected to the adapter on the left level sensor (has something to do with flow). Any of those fail and you wont have fuel flowing from the left side to the right.

Problems with the main pump is the easiest to detect since you would have some drivability issues with loss of power or stuttering with a full tank. If you are just running out of gas and you know there is gas in the left tank, but not in right tank, then most probably you either have a clogged siphon pump on the left side, or the siphon pump have come loose from the weakened adapter on left level sensor, which requires replacing the left level sensor unit.

Check these charts out for 330CI Convertible (Note the arrow in the diagram showing the front of the car, so left and right are reversed here):
http://www.realoem.com/bmw/showparts...72&hg=16&fg=05

http://www.realoem.com/bmw/showparts...73&hg=16&fg=15

You are right about the functionality.

Sorry I didn't update my question. I opened it up a few weeks ago and saw that the sucking jet pump was disconnected from the level sending unit (which is just a sensor that sends the gas level of the tank to the computer). The tab on the level sending unit that holds the sucking jet pump connected had experienced fatigue and was too loose to keep the pump on when the car experienced strong vibrations. I connected the sucking jet pump to the level sending unit again, sealed everything up, and started the car. The OBC told me that the small tank was now empty.

I ordered a new unit and popped it in since the sucking jet pump would have fallen off again without a proper tab.

BTW, I think the PN above for the level sending unit is for a vert. My coupe PN from realOEM was different and had a blue top, not orange.

You are right Amebos; the charts above are for a convertible. I added a note regarding that.

Thanks that was very useful. My fuel gauge is all over the place. How do I know which sender unit to replace if there is 2

Originally Posted by welshboyof69

Thanks that was very useful. My fuel gauge is all over the place. How do I know which sender unit to replace if there is 2

I updated my post above and added a not to help clarify more.
You can check how much fuel in each tank using the hidden cluster menu #6. Usually, once you have total 30 liters of fuel or less, most of it should be pumped to the right tank after starting the car for few minutes.

Hey guys. Thanks for the thread. Wanted to see what you guys think - I replaced my fuel filter at 80k miles, and now at 118k miles finally the fuel pump died, so I replaced that as well. SO, should I assume that my fuel pump died because my current fuel filter is starting to get plugged again and therefore replace my fuel filter again for good measure to protect my new fuel pump, OR do you think, since it's only been 38k miles since I replaced the filter, I can safely wait for another 20k miles before installing the new one? You know, just to save money and not throw my current fuel filter away prematurely.... This would be assuming that my pump just died from old age (118k miles) and that my filter is probably fine. Any thoughts?

Can someone explain in depth the step of putting the new fuel pump gasket on? Should i put the gasket on the top of the tank and then fit the fuel pump through and then press it down on to it? Or put the gasket on the fuel pump beforehand and then reinstall into the tank?