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Old 09-02-2015, 03:14 PM   #1
bimmernate
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Join Date: Feb 2008
Location: Santa Barbara
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My Ride: 2003 330i ZHP
Fuel Gauge Inaccuracies, Video

I noticed my fuel gauge has been inaccurate for the last few months. Basically, The tank stays "full" for around ~100 miles, and then starts to go down at a consistent rate as a drive after that. Once i'm around 1/4 tank, the odo shows that I drove ~300-400 miles and I know that if I continued driving I would run out of gas since there can't possibly be another 1/4 tank of fuel in there. Also at 1/4 tank when I refill, ~14-15 gallons can go in.

I ran the advanced OBD diagnostics and got these values on a tank that i have driven on about 75 miles since full.

230330 __6.0 = Left 23L, Right 33L
__0559 __6.1= 56L total
__0568 1.62= ??



From my research on these forums, it seems the "1/4 tank empty" symptoms usually describes left sensor problems on the drivers side which is the fuel sending unit sensor, but then other threads say its the "sucking jet pump". I just want to get your opinions before I order any parts and attempt to replace with the DIY I found on this website.


link to part
https://www.fcpeuro.com/products/bmw...FcgaAo8w8P8HAQ
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2003 330i ZHP 6MT
Performance: Koni Sport Struts/Shocks, Eibach Pro-Kit, 17x9 Apex ARC-8, TMS F&R Sway bars, M3 RTABs w/ Vorshlag Limiters, M3 Strut Brace

Aesthetics/Functionality: TFX Projector retrofit by lightwerkz, 20% Tint, OEM Aux Input, Clear corners, LED taillights, M3 Steering wheel, Black kidney grills, mobius dash cam

Last edited by bimmernate; 09-02-2015 at 03:21 PM.
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Old 09-02-2015, 04:04 PM   #2
jfoj
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Dude, you need to replace your fuel pump and filter.

Do your research, read this thread it outlines EVERYTHING.

http://forum.e46fanatics.com/showthread.php?t=929501

The Left/Drivers side of the tank should NEVER have more fuel in it than the Right/Passenger side of the tank.

The sucking jet pumps rarely fail unless someone has screwed around with it.

CLASSIC SOFT FAIL FUEL PUMP, $128 for a Siemens/VDO OEM pump/sender on your doorstep. 15-30 minutes, one small worm drive hose clamp and you will be all set.

Replace the primary fuel pump sending unit, makes sure the arm is correctly snapped into the lever on the sender unit.

Then if you still have issues, worry about the Left/Drivers side sending unit.
__________________
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299

Last edited by jfoj; 09-02-2015 at 04:07 PM.
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Old 09-02-2015, 04:54 PM   #3
BB BMW
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Replace both the fuel pump and sending unit.
If you are in there to replace one, might as well replace both.
You may also want to replace the fuel filter.
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Old 09-02-2015, 04:57 PM   #4
jfoj
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One thing that can happen, but is hard to identify and does not happen often is the fuel level sender float can become fuel saturated and become heavy and read too low. Due to the fact this system has 2 sending units this can cause some funny things to happen.

Also see these links:

http://forum.e46fanatics.com/showthread.php?t=1054842

http://forum.e46fanatics.com/showthread.php?t=1058179

http://forum.e46fanatics.com/showthread.php?t=1078870

http://forum.e46fanatics.com/showthread.php?t=1073902

http://forum.e46fanatics.com/showpos...postcount=1248
__________________
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 09-02-2015, 05:29 PM   #5
bimmernate
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Posts: 681
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Quote:
Originally Posted by jfoj View Post
Dude, you need to replace your fuel pump and filter.

Do your research, read this thread it outlines EVERYTHING.

http://forum.e46fanatics.com/showthread.php?t=929501

The Left/Drivers side of the tank should NEVER have more fuel in it than the Right/Passenger side of the tank.

The sucking jet pumps rarely fail unless someone has screwed around with it.

CLASSIC SOFT FAIL FUEL PUMP, $128 for a Siemens/VDO OEM pump/sender on your doorstep. 15-30 minutes, one small worm drive hose clamp and you will be all set.

Replace the primary fuel pump sending unit, makes sure the arm is correctly snapped into the lever on the sender unit.

Then if you still have issues, worry about the Left/Drivers side sending unit.

Thanks! Thats a very informative thread you made. I'm going to spend some time reading through it first, but it looks like I should just replace the right pump/sending unit and fuel filter (although my fuel filter only has 25k miles on it, it's lame that it would need to be replaced so soon but I do understand that it should be replaced when installing a new fuel pump).
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2003 330i ZHP 6MT
Performance: Koni Sport Struts/Shocks, Eibach Pro-Kit, 17x9 Apex ARC-8, TMS F&R Sway bars, M3 RTABs w/ Vorshlag Limiters, M3 Strut Brace

Aesthetics/Functionality: TFX Projector retrofit by lightwerkz, 20% Tint, OEM Aux Input, Clear corners, LED taillights, M3 Steering wheel, Black kidney grills, mobius dash cam

Last edited by bimmernate; 09-02-2015 at 05:29 PM.
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Old 09-02-2015, 05:33 PM   #6
jfoj
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Quote:
Originally Posted by bimmernate View Post
Thanks! Thats a very informative thread you made. I'm going to spend some time reading through it first, but it looks like I should just replace the right pump/sending unit and fuel filter (although my fuel filter only has 25k miles on it, it's lame that it would need to be replaced so soon but I do understand that it should be replaced when installing a new fuel pump).
If the filter only has 25k miles on it, just replace the fuel pump for now and see what happens.

Make sure the fuel tank has less than 3/4 tank otherwise you leak a fair amount of fuel.

I would not worry too much about the drivers/left side sensor at this point.

Keep your old pump in case the float is the same for the drivers/left side and you found out it is fuel saturated.
__________________
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 09-02-2015, 06:15 PM   #7
glhx
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These sending units get sulphur build up. Take it out and clean it with a wire brush and some contact cleaner. On the metal contacts. Those units work together.....if either of them are corroded the gauge will be off. My own fuel pump is on borrowed time at 150k but hold the right pressure with and without load. You can test this to filter out a possible failure at the fuel rail. I did replace fuel filter at 115. This helps the pump not work as hard and possibly makes it less prone to fail prematurely

I've had both of them out and found that both sending units need to be cleaned this way. This could help. It made mine work after finally getting around to it. Ten years and cheap gas do this sort of thing.
Once you see the drivers side sending unit you will notice the very simple design.

Last edited by glhx; 09-02-2015 at 06:16 PM.
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Old 09-02-2015, 06:43 PM   #8
bimmernate
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Quote:
Originally Posted by jfoj View Post
If the filter only has 25k miles on it, just replace the fuel pump for now and see what happens.

Make sure the fuel tank has less than 3/4 tank otherwise you leak a fair amount of fuel.

I would not worry too much about the drivers/left side sensor at this point.

Keep your old pump in case the float is the same for the drivers/left side and you found out it is fuel saturated.
Will do. I'm leaning towards replacing the unit versus just cleaning it since i'm at 111k miles and the car is 12 years old and will be in a place next year where I won't easily be able to work on my car. I just want to make sure I am understanding everything correctly.

Watched the DIY video, looks pretty easy.


The parts to order, am I missing anything? Is that the right gasket? Does the relay have to be done?:

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2003 330i ZHP 6MT
Performance: Koni Sport Struts/Shocks, Eibach Pro-Kit, 17x9 Apex ARC-8, TMS F&R Sway bars, M3 RTABs w/ Vorshlag Limiters, M3 Strut Brace

Aesthetics/Functionality: TFX Projector retrofit by lightwerkz, 20% Tint, OEM Aux Input, Clear corners, LED taillights, M3 Steering wheel, Black kidney grills, mobius dash cam
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Old 09-02-2015, 07:30 PM   #9
jfoj
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Here is what I will tell you, the pump is $128 on your doorstep from www.bmaparts.com and use SPECE30 discount code. Free shipping and if you order standard shipping you will typically get the pump in 2 days as they drop ship from all over the US.

As for the gasket, I reuse these all the time, never a problem.

Clamp you can pick up locally at any parts store, hardware or home center.

Filter, well, you can do this now or wait.

Smart move if the pump is original, you WILL NOT regret replacing it.
__________________
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 09-03-2015, 01:04 AM   #10
bimmernate
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Quote:
Originally Posted by jfoj View Post
Here is what I will tell you, the pump is $128 on your doorstep from www.bmaparts.com and use SPECE30 discount code. Free shipping and if you order standard shipping you will typically get the pump in 2 days as they drop ship from all over the US.

As for the gasket, I reuse these all the time, never a problem.

Clamp you can pick up locally at any parts store, hardware or home center.

Filter, well, you can do this now or wait.

Smart move if the pump is original, you WILL NOT regret replacing it.
Thanks! I ordered from BMA using the spece30 code. I got the pump, fuel filter, and O-ring (just in case). I went through my maintenance history and it turns out there is actually 35k miles on the fuel filter, so mine as well change it at the same time as the pump. Hopefully this solves my problems! I'll post back here once everything is done with the results.
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2003 330i ZHP 6MT
Performance: Koni Sport Struts/Shocks, Eibach Pro-Kit, 17x9 Apex ARC-8, TMS F&R Sway bars, M3 RTABs w/ Vorshlag Limiters, M3 Strut Brace

Aesthetics/Functionality: TFX Projector retrofit by lightwerkz, 20% Tint, OEM Aux Input, Clear corners, LED taillights, M3 Steering wheel, Black kidney grills, mobius dash cam

Last edited by bimmernate; 09-03-2015 at 01:06 AM.
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Old 09-03-2015, 09:46 PM   #11
glhx
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You will want to clean or replace the drivers side unit as well. Usually when one has build up they both do.
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