Mercedes-Benz Forum banner

Changed my fuel pump to fix my fuel gauge, and got an added BONUS.

8K views 15 replies 16 participants last post by  alphonsohall 
#1 ·
I changed my fuel pump today in my 99 ml430 to fix my fuel gauge. I bought the car about a month ago knowing it had this problem and ordered the pump. After changing the pump I went to the gas station to fill the tank and the guage is now working correctly !!!!! But I also noticed that take off from a stand still was tremendously better? It wasn't running bad before but there is now a huge difference in how well the car accelerates !!! occasionally I would feel a slight miss when accelerating at medium speed. This was going to be another proj. but it is now FIXED. I got a two for one deal..... I guess the old pump had low fuel pressure? The car only has 70k on it?
 
#6 ·
mikewired said:
I changed my fuel pump today in my 99 ml430 to fix my fuel gauge. I bought the car about a month ago knowing it had this problem and ordered the pump. After changing the pump I went to the gas station to fill the tank and the guage is now working correctly !!!!! But I also noticed that take off from a stand still was tremendously better? It wasn't running bad before but there is now a huge difference in how well the car accelerates !!! occasionally I would feel a slight miss when accelerating at medium speed. This was going to be another proj. but it is now FIXED. I got a two for one deal..... I guess the old pump had low fuel pressure? The car only has 70k on it?
When the gauge goes bad 9x outta 10 it's the FSU (Fuel Sending Unit) that has gone south..........price @ $60 w/ 1 hr to replace. I check that prior to messing w/ the fuel pump. Just my 2cents
 
#9 ·
sazodada said:
When the gauge goes bad 9x outta 10 it's the FSU (Fuel Sending Unit) that has gone south..........price @ $60 w/ 1 hr to replace. I check that prior to messing w/ the fuel pump. Just my 2cents
Fuel sending unit is not the primary cause of fuel gauge failure. May be 3 out of 10 not 9 out of ten. Do a search and find out the real world experience of ML owners and you'll find Instrument cluster, fuel damping logic (Software) and fuel sending unit are the cause of fuel gauge failure. And based on my observation majority is caused be software or fuel damping logic.

This observation appears to be confirmed by the TSB that instruct technician not to replace Fuel sending unit or Instrument cluster without resetting the system or reprogramming the damping logic per instruction. Most of the time this procedure corrects the problem.

Also, as others said, you can't buy the sender alone. Even if you could, it won't be wise to replace the sender without replacing the pump and filter while you are there. The labor hours you'll spend to access the unit makes it cost effective to do all at the same time. Your estimate of 1 hour to replace the sending unit is probably correct when the fuel pump is out of the tank.
 
#11 · (Edited)
I was trying to find out if the faulty fuel level problem in my car is from instrument cluster or fuel sending unit. I removed the Fuse #5 (instrument cluster) and put it back in. Now the gauge is back up. Before it was at the yellow light even though the tank was full. I am not sure it will remain that way after a refuel.

Where is the TSB you mentioned. I wonder removing the fuse will reset the gauge or should I do per instructions in TSB? Surely I don't how to program the damping logic.
 
#10 ·
mikewired said:
I changed my fuel pump today in my 99 ml430 to fix my fuel gauge. I bought the car about a month ago knowing it had this problem and ordered the pump. After changing the pump I went to the gas station to fill the tank and the guage is now working correctly !!!!! But I also noticed that take off from a stand still was tremendously better? It wasn't running bad before but there is now a huge difference in how well the car accelerates !!! occasionally I would feel a slight miss when accelerating at medium speed. This was going to be another proj. but it is now FIXED. I got a two for one deal..... I guess the old pump had low fuel pressure? The car only has 70k on it?

I just had the fuel pump/sending unit and filter replaced on my daughters 2000 ML320. The guage has been faulty since I bought it for her a few months ago. When you fill it up, it would go to empty, the yellow light would flash some, then after 20 miles or so all would be fine. But then it got worse with it dropping down to a 3/4 tank when full and you could actually watch the needle drop. Anyway, all works perfect now! And I too noticed the car was a little quicker! :D

Ken
 
#12 ·
I've had many ML's in my family, being as my family owns a mercedes dealership. All of the ones my mother has told me she had have had very tempermental gas gauges. My fathers 2001 ML320 never had a gas gauge problem, but my 2004 ML500 is somewhat tempermental, as in it will go up and down at times. This can be fixed??
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top