Faulty gas gauge...

Good day all!!

I am getting close to getting back home to my X5... I bought it cheap with more than a few things wrong with it... They were all fairly easy to fix, but the gas gauge issue has me stumped!!

I drove it to Florida for our cruise and that is when I noticed the gauge acting funny... It worked just fine during the trip expect after getting gas... If I filled it with 1/4 left on the gauge, it remained at that 1/4 level and continued to operate normally (as gas was used, it dropped)... Until it hit 0 miles left... I knew I had about 3/4 or so gas left so I just kept going... Sure enough, the next fill up (guessing) I only needed about 2/3 a tank... This time I cycled the ignition a few times... It reset on the fourth... The next fill up, it did it again, but I was closer to empty... I just drove for a while, then threw it in N, turned it off, then back on and restarted the truck... It cleared it... And on we drove...

So, what would keep the gauge from registering the new level, but still drop as normal? It's almost like the sending units in the tanks only give an initial reading, then the computer adjusts the gauge as the injectors fire... Seems like an odd way of displaying fuel...

Thanks all!!

Cheers!!

One or both senders would appear to be faulty.

An E39 owner had it fixed by using a bottle of Techron Concentrated in the gas tank. Search for it in E39 sub-forum. It doesn't hurt to try.

Originally Posted by tmvseattle

An E39 owner had it fixed by using a bottle of Techron Concentrated in the gas tank. Search for it in E39 sub-forum. It doesn't hurt to try.

Thanks Seattle!! I will try that when I get home... What I don't understand is why the gauge would continue to operate correctly (still head toward empty as fuel was used) after I filled up on our trip, but from the point it was at before the fill up...

On another note, I see you also have an E39 (or two)... I just sold my 98 540i sport and miss it enough to get a newer one; maybe a 2001... I sold my 98 with 253K miles... It has been, by far the best car I've ever owned!! The original fuel pump lasted over 240K miles...

Okay, enough of that... Thanks again!!!

Cheers!!

Good day all!!

Well, I found out what the problem was... Some may believe this and others may not, but it was the battery... I bought the X5 with a weak battery... It would start fine and drive fine, but I noticed a few oddities with the electronics... The remotes, the fuel gauge... I had to let it sit for more than a few weeks and when we got back, the battery was totally dead... I jumped it and it charged, but I don't think it ever got back to 100%... I bought an Interstate battery for $153 and everything has been working great ever since...

I hope this experience helps!!

Cheers all!!