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      03-25-2023, 09:10 AM   #1
e92Rithy
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Fuel Gauge not reading correctly

Hi all,

Fuel gauge is not reading correctly even after replacing both level sensors in both sides of the tank. Anyone know what other possible reasons why itís not reading correctly?

Thanks
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      03-25-2023, 09:53 AM   #2
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*Side Note*

Upon checking my hidden menu 6, I have seen that my right side only reads a max of 17.5 while my left side goes upwards up 20+ while driving.
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      03-25-2023, 09:06 PM   #3
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This is what the hidden menu reads after I fill up.
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      03-25-2023, 09:50 PM   #4
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Quote:
Originally Posted by e92Rithy View Post
This is what the hidden menu reads after I fill up. [L: 27.5; R: 17.6; Sum= 45]
If that is immediately AFTER filling up:
1) Did you fill until Pump Nozzle clicked off?
2) Did you read Fuel Gauge position BEFORE you did hard-right turns on skid pad?
3) Was Gauge reading ~ 3/4 tank?
4) As fuel is consumed, does R Tank reading remain same while Left decreases -- to a point, at which R reading then decreases?

Last question relates to testing for prevention of signal value greater than ~ 64% of max value for Right Tank Sensor.

My guess would be that either the RIGHT Tank Level Sensor or its wiring between Tank & JBE has an issue.

Your filler tube fills the Right tank first and then it overflows into Left Tank. Immediately AFTER filling, I see NO WAY you would have MORE fuel in Left Tank than Right. Both INPA & ISTA show Higher value for Right Tank than Left on my 328xi, as the Jet Pump pumps fuel from Left Tank to Right Tank 'cuz pump is in Right Tank. ISTA shows Ohms resistance of Level Sensor signal, and INPA shows unidentified values. Both Ohms and unidentified values INCREASE with increased fuel level.

Perhaps someone who has examined/ replaced the Right Tank Level Sensor can suggest cause of your issue.
George
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      03-26-2023, 12:51 PM   #5
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Quote:
Originally Posted by gbalthrop View Post
If that is immediately AFTER filling up:
1) Did you fill until Pump Nozzle clicked off?
2) Did you read Fuel Gauge position BEFORE you did hard-right turns on skid pad?
3) Was Gauge reading ~ 3/4 tank?
4) As fuel is consumed, does R Tank reading remain same while Left decreases ó to a point, at which R reading then decreases?

Last question relates to testing for prevention of signal value greater than ~ 64% of max value for Right Tank Sensor.

My guess would be that either the RIGHT Tank Level Sensor or its wiring between Tank & JBE has an issue.

Your filler tube fills the Right tank first and then it overflows into Left Tank. Immediately AFTER filling, I see NO WAY you would have MORE fuel in Left Tank than Right. Both INPA & ISTA show Higher value for Right Tank than Left on my 328xi, as the Jet Pump pumps fuel from Left Tank to Right Tank 'cuz pump is in Right Tank. ISTA shows Ohms resistance of Level Sensor signal, and INPA shows unidentified values. Both Ohms and unidentified values INCREASE with increased fuel level.

Perhaps someone who has examined/ replaced the Right Tank Level Sensor can suggest cause of your issue.
George
Hi to answer your questions. Yes gauge reads 3/4s after I fill up and wonít go past it. R reading remains the same even while the L reading goes down. Where would the wiring be for the right side tank to the JBE be? I was the one that replaced both sensors. Even did ohm tests on the sensors before putting them into the car.
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      03-26-2023, 02:10 PM   #6
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Quote:
Originally Posted by e92Rithy View Post
Hi to answer your questions. Yes gauge reads 3/4s after I fill up and wonít go past it. R reading remains the same even while the L reading goes down. Where would the wiring be for the right side tank to the JBE be? I was the one that replaced both sensors. Even did ohm tests on the sensors before putting them into the car.
I've NEVER had to open my tank, or had any issue with the Fuel Level Sensors. I would HOPE someone who HAS (perhaps you? ;-) can indicate HOW/IF the Right Tank Level Sensor has moving parts. Is there a possibility that a hose or such is preventing a float from rising to full height?

If there IS such a float or other moving arm on the Sensor, and it reads the SAME 17.6 value you show until the Left Tank is nearly empty, and THEN the Right Tank Level Value falls to Near-zero as fuel is consumed from Right Tank, there is PROBABLY NO electrical fault in R-Tank Level Sensor signal as received by the JBE.

I would rule out a mechanical restriction on Float Arm (or however it works), BEFORE chasing a supposed electrical fault, particularly if the Right-Sensor value acts as I described, remembering that the Jet Pump will pump fuel from Left Tank to Right, until there is VERY little fuel left in Left tank.

I do NOT know how the harness is routed between the tank sensor & JBE, but I would NOT expect there to be any issue within the harness. If you don't have ISTA, I can provide Connector Location, and Connector View (showing Pin #s & wire colors) of Connector at Pump, and Connector at JBE. I would want to know about "float arm" 1st though.
George
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      03-26-2023, 02:15 PM   #7
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Quote:
Originally Posted by gbalthrop View Post
I've NEVER had to open my tank, or had any issue with the Fuel Level Sensors. I would HOPE someone who HAS (perhaps you? ;-) can indicate HOW/IF the Right Tank Level Sensor has moving parts. Is there a possibility that a hose or such is preventing a float from rising to full height?

If there IS such a float or other moving arm on the Sensor, and it reads the SAME 17.6 value you show until the Left Tank is nearly empty, and THEN the Right Tank Level Value falls to Near-zero as fuel is consumed from Right Tank, there is PROBABLY NO electrical fault in R-Tank Level Sensor signal as received by the JBE.

I would rule out a mechanical restriction on Float Arm (or however it works), BEFORE chasing a supposed electrical fault, particularly if the Right-Sensor value acts as I described, remembering that the Jet Pump will pump fuel from Left Tank to Right, until there is VERY little fuel left in Left tank.

I do NOT know how the harness is routed between the tank sensor & JBE, but I would NOT expect there to be any issue within the harness. If you don't have ISTA, I can provide Connector Location, and Connector View (showing Pin #s & wire colors) of Connector at Pump, and Connector at JBE. I would want to know about "float arm" 1st though.
George
Hi,
I checked last night and saw 0 obstruction to the float arm at all. Also I find it weird that I never had this issue either until I replaced my turbos. Which I find odd since thereís 0 correlation between the two. Unless I disconnected something by accident but I wouldnít know. However I have noticed a connecter (I believe the wire colors were black/red/blue and thin) just sitting there near the top of my fuel pump but have no idea where that goes into
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      03-26-2023, 10:44 PM   #8
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Quote:
Originally Posted by gbalthrop View Post
I've NEVER had to open my tank, or had any issue with the Fuel Level Sensors. I would HOPE someone who HAS (perhaps you? ;-) can indicate HOW/IF the Right Tank Level Sensor has moving parts. Is there a possibility that a hose or such is preventing a float from rising to full height?

If there IS such a float or other moving arm on the Sensor, and it reads the SAME 17.6 value you show until the Left Tank is nearly empty, and THEN the Right Tank Level Value falls to Near-zero as fuel is consumed from Right Tank, there is PROBABLY NO electrical fault in R-Tank Level Sensor signal as received by the JBE.

I would rule out a mechanical restriction on Float Arm (or however it works), BEFORE chasing a supposed electrical fault, particularly if the Right-Sensor value acts as I described, remembering that the Jet Pump will pump fuel from Left Tank to Right, until there is VERY little fuel left in Left tank.

I do NOT know how the harness is routed between the tank sensor & JBE, but I would NOT expect there to be any issue within the harness. If you don't have ISTA, I can provide Connector Location, and Connector View (showing Pin #s & wire colors) of Connector at Pump, and Connector at JBE. I would want to know about "float arm" 1st though.
George
Hello, this is a photo of the connector I was talking about previously.
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      04-05-2023, 12:36 AM   #9
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*Update*

Still no luck with this fuel gauge. Anyone have a diagram of connection points for wires anywhere?

Thank you in advance
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      04-05-2023, 08:56 AM   #10
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Quote:
Originally Posted by e92Rithy View Post
... Anyone have a diagram of connection points for wires anywhere?
Attached are ISTA ScreenPrints of Right Tank Level Sensor for 2008 E92 (335i):
1) Wiring Diagram SSP with Lines ID;
2) X697 Location; Connector for Level Sensor wires, 2 small-diameter wires;
3) X697 Connector View; identify 2 pin numbers
4) X14271 Connector (Blue) Location at INboard side of JBE, below JB Fuse Panel;
5) X14271 Connector View, identifying location of pins 9 & 52 for Sensor wires.

If the R Tank level readout goes NO higher than ~ 17.6, remains there until L Sender reads nearly zero, and then
shortly thereafter begins a steady reading to LOWER values, approaching zero, that does NOT sound like a wiring fault to me.
As stated before, the FIRST suspect is a restricted Float Arm. If that has been eliminated, the only thing I can identify
as an electrical fault would be a fault in the sensor itself, OR perhaps LESS voltage supply to R Sensor than Left. However,
I don't see how that would cause reading to stay at 17.6 until ~ 5+ gallons of gas was used. If I have misunderstood the
FACTS of your issue, please correct.
George
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      04-13-2023, 10:53 AM   #11
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Quote:
Originally Posted by gbalthrop View Post
Attached are ISTA ScreenPrints of Right Tank Level Sensor for 2008 E92 (335i):
1) Wiring Diagram SSP with Lines ID;
2) X697 Location; Connector for Level Sensor wires, 2 small-diameter wires;
3) X697 Connector View; identify 2 pin numbers
4) X14271 Connector (Blue) Location at INboard side of JBE, below JB Fuse Panel;
5) X14271 Connector View, identifying location of pins 9 & 52 for Sensor wires.

If the R Tank level readout goes NO higher than ~ 17.6, remains there until L Sender reads nearly zero, and then
shortly thereafter begins a steady reading to LOWER values, approaching zero, that does NOT sound like a wiring fault to me.
As stated before, the FIRST suspect is a restricted Float Arm. If that has been eliminated, the only thing I can identify
as an electrical fault would be a fault in the sensor itself, OR perhaps LESS voltage supply to R Sensor than Left. However,
I don't see how that would cause reading to stay at 17.6 until ~ 5+ gallons of gas was used. If I have misunderstood the
FACTS of your issue, please correct.
George
I can check float arm again to make sure. However I ran an ISTA check on my car and JBE is yellow stating fault code A6E5 (JBE: Fuel level sensor right). I find it odd since I replaced the float already so unless I may have issues with my Fuse box, I donít understand why it is yellow.

Thank you,
Rithy
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