Stuck float sending unit...swag


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To know for sure you start with pulling up test six and see what values are reporting.

I had this problem when the sending unit we sending the wrong values. I have an instruction how to fix.

You maybe have a disconnected wire. More fuel is higher resistance I don't think the system is smart enough to realize that ∞ resistance means it's broken.

Have now started monitoring test six. Seems to be going down ok as the needle moves down. This is a brand new sending unit.

Reserve fuel problem
 

When you first replace a sending unit you have to reset the fuel system I think it's test 21. Look at test 6.0 v 6.1 etc. There is an actual vs buffered value and they should be similar. They will be quite off if a sender every had a bad value.

Also very important that both sides go down and they transition at the right points

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Can you do the reset at any point or best to fill the tank first. Thanks, will look into it.

By the way, I finally purchased a foxwell NT520 pro diagnostic tool.

Any time. It removes the buffeting it can start at 50% or 20%. In my case the buffered amount was 2/3 of a tank so it wouldn't go higher than 2/3 on dash even when full. I reset the buffer and instantly gauge correctly read 1/1.

With a car at this age and mileage (I do not know your mileage), as you mentioned...

1. New fuel pump. Don't know your brand but best is Pierburg, which is OEM.

2. New fuel filter such as Mahle, Mann etc.

3. The siphon pump/sending unit, best is BMW brand.

Anything else may create a guess and time/effort lost in troubleshooting.
I understand that some people use aftermarket fuel pump (? Walbro) etc. and seem OK.
I use aftermarket parts all the time, such as NGK spark plugs, but when it comes to fuel system, I stay with BMW genuine supplier for a few reasons:

1. You can get stranded in the middle of nowhere ---> hotel cost, towing cost, inconvenience etc.

2. Time/effort lost + frustration etc.

3. It is not that expensive in the US, I can get a Pierburg fuel pump for US$145.

Thanks for the comments CN. Yes, sender unit I installed is genuine BMW. Fuel pump was installed by local mechanic so not sure if the sending unit on that side was replaced or just the pump. I havent replaced the filter. Just monitoring the fuel drop on test 6 at the moment to see if I can get past half way mark. Have spare gas in the back just in case. Will keep you posted. Need to check out my NT520 as well. cheers

Watch your hidden 6 menu.

If the right side drops to zero get fuel immediately no matter what the left side says.