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  #11  
Old 02-19-2019, 04:06 AM
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Still waiting to get down to the level. I have a RHD vehicle so are the two sides laid out the same I wonder? When I get the seat off I will of course know. By the way if it is the o-ring I was trying to find it on ebay but maybe I have to go to the hardware store. I suppose you had to disconnect all the connecting pipes and pull the unit out to be able to replace the o-ring?

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  #12  
Old 02-19-2019, 02:04 PM
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Reserve fuel problem

The tank is the same regardless which Side the steering wheel. So left side for the siphon jet right side electric pump.

In aus you might find the o-ring at a store, in the USA unlikely at it's a metric size. I think somebody measured the size and it's in my repair thread.
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  #13  
Old 02-28-2019, 07:47 PM
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Ok, so I finally got the fuel dowm. Below is an image of one side getting down to 0.7L. Note the guage is almost at quarter (20) where the light comes on and the engine dies. The fuel left has dropped below your magic number of 1.5L and I found it started to be erratic. It would drop to 0.4 then back up to 0.8 then even down to 0 then up to 1.4/1.5 then back down. At this point I happened to be near a service station (that’s what we call them in Australia) and so I wasn’t going to risk it and put some fuel in. Looks like I need to get on ebay and get one of those rings..)

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  #14  
Old 02-28-2019, 11:07 PM
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When the right side hits zero there will be close to 1 gallon left but since lots of fuel goes in circles that will go a lot quicker than the engine consumes it.


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  #15  
Old 03-01-2019, 10:08 AM
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Quote:
Originally Posted by andrewwynn View Post
When the right side hits zero there will be close to 1 gallon left but since lots of fuel goes in circles that will go a lot quicker than the engine consumes it.
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Andrew...if I'm not mistaken...shouldn't the OP's OBC TEST 6 be showing 0.0 liters of gas on the left side in the scenario presented?

My thinking was that the left value (listed) in TEST 6 will go to zero first (fuel gauge should register around 1/2 tank)...then the right value then starts to go to zero.

If the OP has 1/4 tank of fuel left in the tank...TEST 6 should be showing 0.0 on the left side...and 0.7 on the right side.

Question to TallJames...does the left value (of TEST 6) ever change? If not, then perhaps something is wrong with the left fuel level sensor, too. And when you go to the 3rd screen of TEST 6...what "PHASE" is it giving?
  • PHASE 1 - regular computing method by way of sensors (both sensors OK)
  • PHASE 2 - calculation in progress from TKVA signal (sensor faulted)
  • PHASE 3 - fuel tank contents can not be computed, fuel gauge reads 0 (at least one sensor is faulted)
Example of TEST 6's 3rd screen:
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  #16  
Old 03-01-2019, 08:56 PM
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It is a bit confusing!

To start with, both side fall in level but as the right side is a smaller volume, it will get to a low number first, then it should sit there while the left side keeps dropping.

The right side will go down to about a litre or two and as fuel is used from this side, it's "topped up" from the left side by the siphon.

If the siphon isn't working, the left side still contains fuel but it cannot get over to the right side where the pickup is, so the total fuel level reads about 1/4 tank but the right side is empty and the car dies (or is hard to start).
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  #17  
Old 03-02-2019, 02:47 AM
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@Quick:

wpoll paid attention in class and did a fine job of explaining.

You are correct in saying the OP "should" be doing as described. The fact it does not indicates a failure and the text 6 will weed out that failure.

When operating normally, both fuel sensors will start to move once about 10L has been consumed. (Before that they are both "pinned" against the top of the tank. (for all those wondering why it takes so long for any car to have the fuel gauge drop from full. That is why).

As fuel is spent from the X5, the right side being smaller will drop to near zero while the left side will drop to about 30L. At this point, the left and right sides will become separate.

Since there is only one fuel pump and that is on the right side, the siphon jet delivers a constant stream of fuel from the left side to the 5L "surge tank" or well on the right side where the electric fuel pump lives.

When operating normally, the siphon delivers far more fuel than the engine can consume so the right side is filled to overflowing and spills right back to the left side. If the siphon jet is not working properly it's usually that o-ring defect or maybe 10% chance the electric fuel pump is weak. (makes enough psi for the engine but not enough left over to operate the siphon).

Everybody with an X5 should run test six and drive down to single digits miles to empty to confirm the right side of the tank will hold steady to the bitter end.

If the right value gets to zero before the left, there is a failure that needs to be addressed. 90% chance siphon jet o-ring, 8% chance soft fail fuel pump, 2% something else like FPR or siphon pressure release valve or plugged foot.

If tracked many dozen threads on the topic, I only saw maybe two that were a soft fail electric pump the rest all siphon jet, sadly most people replaced the whole left fuel assembly rather than just the 50˘ o-ring.


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  #18  
Old 03-02-2019, 01:21 PM
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Thanks for the refresher course WPOLL and Andrewwynn...just looking at the OPs TEST 6 didn't make sense (to me) with the left side of the tank displaying that much fuel and the right side of the tank being much lower.
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  #19  
Old 03-06-2019, 05:50 AM
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Thanks for those Phasor information qSilver7 and comments from everyone. I have ordered the o ring from the usa to here and will do the job in due course. The left value does indeed drop. I will post of the phase information the next time I am out and about.
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  #20  
Old 03-10-2019, 11:15 PM
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So, I checked the phase. Great to know how to access this info. It is showing Phase 1 so I assume the sensor electrics are working ok. Just waiting on theo-ring now.

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Last edited by talljames; 03-10-2019 at 11:57 PM.
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