Fuel Gauge, Road Trip

weiln12 · #1 11-02-2015, 02:44 PM

All,

Just took the X5 on a road trip from SLC to Denver and back this weekend. Overall she did fantastic and the new transmission seems to be running great. I did have one issue though...

The gas mileage appears to be REALLY good. On the way out from SLC to Denver I took I-80 across Wyoming and was averaging 20.5MPG according to the OBC. Actually, the whole trip from SLC to Denver and back (coming back was across I-70) I averaged 19.5MPG.

The one issue I had was about 16 miles from Laramie. OBC said about 120 miles for range and the gauge said around 3/8th full. Then all of a sudden the gauge said FULL, and the range started climbing. I stopped in Laramie, and put 21.8 gallons in. From what I read, the tank is 24.5 with a 2.5 gallon reserve which means that prior to it going wonky, everything appeared to be reading correctly. 21.8 gallons got me right about 440 miles.

I've not seen this problem before, and the rest of the trip was fine as well. I saw the posts about the gauge reading 0, and I'll try the Test 6 today. But has anyone seen a gauge go to FULL? Also, 20MPG seems really good for traveling between 80-85MPH across Wyoming. I'm not complaining, just surprised!

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Qsilver7 · #2 11-02-2015, 03:18 PM

Just for clarification...because it does confuse many owners...the V8s are "given to have" a 24.6 gallon fuel tank...and the "reserve" of 2.6 gallons is included within the 24.6 gallons...not in addition to 24.6 gallons.

So on the V8s...when the fuel gauge is reading approximately 22 gallons of fuel remaining in the tank...that is when the fuel level sender's data is used to illuminate the low fuel light on the fuel gauge.

As you can see in the page from the facelift owners manual below...the V8 & I6 have different "reserve fuel" amounts...thus the low fuel warning goes off at a different tank level for the I6 versus the V8:

When the fuel level senders registers 22 gallons or 22.5 gallons remaining (respective of being a V8 or I6)...that is when low fuel warning is illuminated...see illustration below:

bcredliner · #3 11-02-2015, 03:29 PM

Quote:

Originally Posted by weiln12

All,

Just took the X5 on a road trip from SLC to Denver and back this weekend. Overall she did fantastic and the new transmission seems to be running great. I did have one issue though...

The gas mileage appears to be REALLY good. On the way out from SLC to Denver I took I-80 across Wyoming and was averaging 20.5MPG according to the OBC. Actually, the whole trip from SLC to Denver and back (coming back was across I-70) I averaged 19.5MPG.

The one issue I had was about 16 miles from Laramie. OBC said about 120 miles for range and the gauge said around 3/8th full. Then all of a sudden the gauge said FULL, and the range started climbing. I stopped in Laramie, and put 21.8 gallons in. From what I read, the tank is 24.5 with a 2.5 gallon reserve which means that prior to it going wonky, everything appeared to be reading correctly. 21.8 gallons got me right about 440 miles.

I've not seen this problem before, and the rest of the trip was fine as well. I saw the posts about the gauge reading 0, and I'll try the Test 6 today. But has anyone seen a gauge go to FULL? Also, 20MPG seems really good for traveling between 80-85MPH across Wyoming. I'm not complaining, just surprised!

24.5 includes reserve. Have not seen tank gauge jump but range will change when fuel flow increases or decreases per throttle position and speed. 20MPG is good but others here have posted better. I wouldn't complain for sure.

Best way to check mileage is fill the tank, note the mileage, drive some number of miles, fill it up again and divide the number of miles driven by the gallons that it takes to fill it up the second time.

weiln12 · #4 11-02-2015, 03:38 PM

@Q - Ah, ok, that makes sense. In this case then, I'm glad I stopped as something was clearly not working correctly. If I put 21.8 gallons in, then it was a lot closer than I feel comfortable with.

This is also the only time I've seen this happen. Typically, it's very close. On the way back I checked mileage with how many gallons I put in and everything was right on. I like to reset the trip odo whenever I fill up, just so I know how far I've gone on a tank. Being this was the first real trip in the X5 I wasn't sure of what to expect, but now I know.

cn90 · #5 11-02-2015, 11:42 PM

Put some Techron in the tank...

weiln12 · #6 11-03-2015, 11:27 AM

I'll put some Techron in, is it any better than Lucas? The gas I get is usually from a Sinclair station which I think is good gas. Next week when I'm back in Idaho most of the places have ethanol free premium. Not sure if that'll help this, but my previous vehicles seemed to like it better.

Also, pulled up the Test 06 today. I filled it up, and test 06 only shows 55/27/82. Seems like I'm missing about 11 liters or 2.5 gallons here. My truck usually stays on FULL for quite some time and this could be why.

Ricky Bobby · #7 11-03-2015, 11:30 AM

Lucas Fuel Treatment is more of a lubricant additive although it does clean a little bit. Techron and Seafoam are definite cleaning additives, I use both interchangeably.

weiln12 · #8 11-03-2015, 11:37 AM

@Ricky - Thanks for that, didn't realize the difference. I've heard that Techron is the best cleaner so I was just curious.

Qsilver7 · #9 11-03-2015, 11:37 AM

If possible...now that you have a full tank, every time you start the vehicle or take a drive...open TEST 6 and monitor the fuel. The left side, if registering 55 liters...should start decreasing...eventually to "0"...then the right side should start decreasing.

BTW, for those that may be confused as to why there's an unequal amount of fuel registering on a full tank of gas... unlike the other models like the e38/e39 etc...the e53 fuel tank is not equally bifurcated (divided into two)...the left side is larger than the rights side...thus the "unequal" representation of left side/right side fuel level on a full tank.

If there's a big fluctuation or change...perhaps it will prevent itself while monitoring the fuel consumption.

[center]E53 X5 fuel tank...left side is larger than right side

weiln12 · #10 11-04-2015, 12:02 PM

Put some Techron in, we'll see how it goes. I'd be surprised if they're "sticking", since they appear to be a hard limit. I've driven almost 30 miles since my fillup and the tank still reads 55/27/82.

I've noticed that under acceleration now they'll both drop and then come back up. Under a RIGHT turn the RIGHT side will drop and come back up, and for a LEFT turn the LEFT side will drop and come back up. Under braking or headed downhill they both stay and don't drop. Weird, funny, cool, or just interesting.

There definitely seems to be a stopping point at 55/27/82 though. They never register more than that, which to me would indicate that is a hard limit. I'll keep watching it and see what happens.

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