GDawgC220

last night, the ML registered a little less than 1/2 tank of gas.

this morning, I go drive my brother to school in the ML, it's about the same. As i'm driving along, I notice the gauge moving down a little, normal I figure.

By the time I get to his school, it's above the last quarter mark. I'm thinking, I have been flooring it, maybe it's thirsty today :p

On the way back, I check the overhead computer to see how many miles I got cuz I have to go out later in the day to do some errands, so I figure I'll get gas then cuz it says about 66 miles left. Fine.

5 minutes away from my house, the reserve light comes on I'm like, WTF, how can it eat 4 gallons of gas in a matter of 20 minutes...

Slowly, the gauge goes down and down and down, pass the reserve light now in a few minutes. I'm thinking either its the gauge going bad again or it's really that I'm out of fuel. but it doesn't make sense...the round trip to his school and back is about 14 miles.

Now in the garage, it registers just right above the 0 mark. Any ideas? Should I try and go to a gas station (if it really is that low, i won't make it as the nearest gas station is 10 minutes away) or call roadside and have them fill up a few gallons?

Darkmann

The ML (and other MB sedans) has always had problems with the fuel sending unit which incorporates the fuel pump. That may be the problem. I don't think it's the gage. Fill her up to the brim (close your eyes when doing this, given the current gas prices!!!!!) and look at the gage. If it doesn't register full, then you may have a sending unit problem. Otherwise you have an OPEC agent in your gas tank.

GDawgC220

the last time something like this happened, it wouldn't respond after filling up. It was just sitting at the bottom with the reserve light on and blinking fuel up top. After a few days, after the next fill up, I started up the car and it was fine again.

Today it just went down slowly, not in one big jump to the bottom.

I had it diagnosed last time it happened and I was told its the cluster itself, they tested the fuel pump/sender and it was fine.

We've had the fuel sender unit replaced once under warranty already and had thought it was the problem again but apparently not...

TheGreat1

its your fuel sender that causing the gauge to jump around. If you still under warranty, just take it in and have them replace. If you out of warranty. Then just take it to any auto repair that works on mercedes, they can do the job..

GDawgC220

so it can't possibly be the cluster/gauge itself? Strange that they told me the sender unit was fine...cuz I asked them to check it out and told me it was all good. What's the cost on the fuel sender replacement?

They said $425 for the cluster replacement...so i want to compare with the sender unit.

thanks man!