bbearden

We have a 2001 ML 320 and originally thought that we were getting very poor fuel economy as the car runs through a quarter tank of fuel in only 53 miles. We filled up and determined that the car only ran through 2.95 gallons of gas during that quarter tank, netting us almost 18 MPG, which is consistent with our driving. The car will register almost out of fuel on the gauge after about 300 miles of driving, versus ~400 or so that it should go. However, when I fill up, I can only put about 16-17 gallons in it. I have never ran it bone dry to see if it will hold the 21.9 gallons Mercedes claims it holds in the owner's manual.

It has been to the dealer several times (under warranty thank God!) for the inaccurate gauge issue and most recently the sending unit was replaced along with two fuel filters, a fuel pump, and new fuel lines. None of this has made any difference in correcting the fuel gauge inaccuracy. Curious if others have had this issue and what the remedy is. Is the instrument cluster in need of a replacement? Thats the only thing I can think of to fix the issue at this point.

mihir_d

My 2000 ML at 102K miles has also been registering a bit off readings on the gauge for the last 30K miles or so...I am told, its the sending unit, but I haven't had it done yet, since its not terribly bad.

In my case, the gauge drops quickly in the first 50 miles of driving or so...but then holds steady and works correctly on the remaining half of the sway...

That's why I have just been living with it..plus the trip computer gives accurate readings so that helps me out...

As for your problem, I wouldn't know what it could be...the dealer should be able to diagnose this correctly and pin point the problem...

bbearden

It sounds like we have the same problem with the first qtr tank dropping off in the first 50 miles and holding steady thereafter. Unfortunately, I don't have the trip computer in my ride so I use the trip odometer. Tonight I pulled fuze #5 out to reset the instrument cluster and also disconnected the fuel pump electrical connection temporarily so we'll see if that makes a difference. If this doesn't work, I may try having the damping logic removed from at the dealership to see if that has any effect.

bbearden

Pulling fuze #5 made all the difference. It's crazy to think that the dealer replaced practically the entire fuel system and the fix was to recycle the power to the instrumentation.

theboogers

was the ignition on when you pulled the fuse or all off? i tried the disconnect for the tank at rear wheel and still did not reset. thanks

bbearden

I did that as well. Regarding pulling fuze 5, yes I kept the ignition on position #2 and waited a full minute to put the fuze back in. It reset my fuel gauge but my clock didn't reset for some reason.

mtnbenzer

I had a 2001 E-430 and one day the fuel gauge would not show full (21 gal on the computer) even though it was full. It would show 18 or 19 or so but never the 21 gal it showed for 4 yrs after filling and following instructions not to keep mashing the fuel handle to get a little more in. MB replaced the fuel sensor ($250 or so) and that cured the problem.

bbearden

You are probably referring to the fuel sending unit. The dealership recently replaced that in the car along with the fuel pump, fuel filters, and fuel lines. MB has really overengineered their fuel system. I've had numerous cars, many of which are classics (over 30 yrs old), and not once have I had a fuel gauge issue.

mihir_d

I may want to try this too....is this fuse located in the engine bay fusebox or is it in the passenger footwell?

bbearden

Its in the passenger footwell. Fuze number 5. Its a 5 amp fuze.

theboogers

after acting up for a while my fuel guage finally dropped dead. i tried the reset of the rear connector at the rear tire, i tried the reset of the #5 fuse with key in number two position. nothing has worked. maybe this works only after you get a new fuel sender installed? any suggestions will be appreciated. guage is on empty with no action. 2001 ml430. thanks

bbearden

If your sending unit is dead then a replacement of it should fix the problem unless your gauge in the instrument panel has died. The stealership is the only people I know of who can diagnose that problem. You could buy the part and put it in, its not very expensive but is a bit difficult to get to. It requires you to remove the rear seat and lift the carpet to get to the access panel for the tank.

Nexus4144

My 98 had that problem once. Took it to the dealer, and if was perfect since then. My 05's are perfect though.

JM15

I just pulled the number 5 fuse and it fixed my gauge problem also thanks for the help

willpower

Resurrecting this thread to deal with a current issue of mine:

So I finally got to my last 1/4 tank after my first fill-up after buying my ride last week. Also started using the trip computer in the overhead console to display how many km I could still drive with my fuel tank.

So here's the interesting thing: when full, the fuel gauge is at 1/1 and trip comp shows 400+km.

But once I got to 1/4 tank (on gauge), not only did the fuel gauge needle move, but the trip computer was telling me: 44km left, 18km left, 6km left, all within 0.3km of actual distance driven. At one point it was showing 0km left after I pulled aside to check. I could've sworn I felt the engine choking.

After taking off again for the nearest gas station, trip comp went back up to 24km and fuel gauge needle rose from the dead, though reserve tank indicator light was still on.

Seemed that during the quickest decline, it was when my ML was pointed DOWNHILL.

When I refilled, I got 57.5L in there, with the trip comp showing 18Km left. Owner's manual say fuel tank capacity is 72L, incl 12L reserve.

So what I'm asking is if anyone else is or has experienced similar fuel gauge erratics, esp when driving downhill or when starting up from cold.

If so, what did u do to remedy the issue to get accurate fuel gauge readings?

My biggest concern is that my engine will choke out while in hill descent just because the fuel is "flowing the wrong way".

(had an issue with my 202 years ago when it showed 1/2 tank on fuel gauge but choked out on freeway. Towed to stealership and got raped for close to $1G in towing and "repairs". Culprit was the crappy fuel sensor, and stealership told me to only fill up everytime to avoid this problem in the future. This time around I want to avoid such problems, esp during my roadtrip from Vancouver BC to LA and back next week )

TIA for replies, experiences and advice!!

sweeper

This issue plagues the"M" w163 series. I haver tried everything from fuse pulling to not overfilling the tank. The fuel gauge has a mind of it's own! I have had it only going up 3/4 tank when filled to the other day, an almost full tank and the trip computer read 537km range. which is about right (I hope!) so by keeping an eye on the trip computer I'm going to find out exactly what the car will do or fill it when I chicken out. Hopefully this will give me a good "gauge" of available distance. Seeing that a fuel sensor unit in Oz will cost me my first born and is no guaranteeing of a fix, its the cheapest way of a fix.