99 ML430 Fuel Pump Problems @ 75K miles
 

The dealership is having major problems fixing my fuel pump. This time is the 3rd time in 2 months, 4th in a year, that my ML is in the shop for the fuel pump. The manager tells me each time that they put a new one in and this won't happen again. Well the first 2 times I believed them because I figured since I am not paying for it, it must really be fixed. Can someone give me any advise on what I might tell the dealership to fix since they obviously don't know what to do.

A very common fault of those pumps is too over heat and it actually fries the harness at the pump. have them do a thorough check of the electrical connector at the pump and also do an amp draw test of the new fuel pump. If the new fuel pump draws 9.0 amps or more, you may have wiring problem. They shouldn't charge you more than half an hour to check the draw. Also put in a new relay.
Fuel pump issues are very common on those vehicles, but the later pumps are much better than the originals. There's no good reason to be back in there four times in one year........

Thanks...I'll relay your thoughts to the dearlership.

Fuel contanimation is the MOST likely cause....the 1998-99 ML's had that problem from the factory...we tried every thing BUT only a fuel tank was the solution!

WE installed at least 40-50 tanks in those trucks....

Do you think that the fuel pump is bad? How much does a new fuel tank cost? What should I have the dealership replace (fuel pump, fuel tank, etc)?

Since the tank can't be drained OR cleaned once the fuel is contaminated it stays that way.... JUST keeps killing fuel pumps..we installed ALL of those tanks DUE to repeated fuel pump replacements!

DOC, besides the obvious, is there a good tell tale sign when it is contaminated? We don't have a good fuel test kit here. If I don't see anything abnormal in the tank and the smell/color of the fuel appears normal, is there something obvious to check?

We couldn't even see any contamination in the fuel tanks on those early ML's, but MBUSI in Vance Alabama assured us that that was the problem & that their MAIN tanks were the problem..

Sugar OR other contaminates will not be seen BUT a local fuel distributor can check for those problems.

Sorry for my misunderstanding...but are you saying that I should have the fuel pump, fuel tank, and all the electrical components replaced? Is this gonna be like a $2K job?

I'd definitly get the amp draw test done FIRST. It should take them all of 20 minumtes to check that. Makes sure they check it with the engine up to operating temp. I've had several pumps that when started drew around 6 amps, and then after a while the amperage would climb above 10 amps= BAD. So it's not always immediatly obvious.
And money wise, it's probably cheaper to have a fuel sample sent out before throwing a fuel tank at it. Like DOC said, they couldn't even see the contamination.

DUH, forgot to ask what your original symptom was. Why do they keep throwing fuel pumps in?

will do...thanks you guys are a big help

When trying to start it, it just goes vrrrrvrrrrvrrrr. Happens about a week or so after I get it back from the dealership. This last time, it happened the day after I put gas into it.

Well...the fuel was tested, amps to the pump as well. Nothing abnormal found. The dealership has sent a request for help to the school house. Hopefully they get the answer to fix this. Any thoughts from you guys??

Not amps "to" the pump. that could be mis-understood as power to the pump.
Need meaurement of amp draw OF the pump when running, ESPECIALLY when engine is hot and vehicle has idled for a while.

When does the car not start? When hot, after sitting overnight? Does it die while driving? Does it die at idle......

It might not be caused by the fuel pump, but by a faulty CPS.

http://www.whnet.com/4x4/pix/CPS.jpg

I agree with ML320................ possible CPS failure. Very common problem that leaves no codes. Happened to me this past winter. My 2 cents.

It friggin' better not be. If it's at the dealership, and they're putting in the fourth fuel pump this year, I would hope they have a brain enough to have already checked the CPS multiple times........

Everytime it has been the first time that day that I tried to start it. One time it died right after I got gas, but after a few minutes it started only to die the next day when I tried to start it. I'm starting to think that it will never be fixed.

2000 320ml fuel pump failure
 

Attachment 35512About a month ago I had the fuel pump fail on my 2000 320ml. 55,000 miles. My indy mechanic found the electrical connection had burned through the top allowing gas to escape the tank and weep down the side of the fuel tank. Upon further inspection, he found the internal wiring had melted. He felt that it was due to a clogged fuel filter or pump. Either way the electrical system should have blown a fuse or something before it melted the wiring inside the fuel tank. Mercedes dealer and southeastern dealer rep said they had seen this before but it had not caused any fires to date. They could not assure me that this could not happen again. Has anyone experience as similar situation?

That's very common actually. I don't know why MBDOC says the tank is the "MOST" common fault. Fuel pumps on those SUV's are crap, especially the early ones. Thankfully fuel doesn't burn in liquid form, otherwise there would be a lot of ML's catching on fire. The pump has a 20 amp fuse, but I've pulled out melted pumps that only drew 10 amps.
I find a handful of those each year and have been since they were new. Haven't found one on a newer SUV though, 2002 and newer

my fuel pump relay keeps melting
 

I have now gone thru 2 fuel pump relays on my 99 ml 430 , 160K,
The dealership wants $130 to dinog. but from what I am reading the wiring problem seems to be the issue.
My ml will not start in the morning due to the power draw all nite...which drains the battery. So I pull the relay and the car starts. This is getting old real fast.
what is the cheapest way to fix this issue. I can imagine I have the only ml with this problem and the dealership should know this is a problem.

The 20amp fuse is warped alittle but not blown , which is next to the Fuel pump relay. The relay is very warm to the touch when pulled.

The vehicle performs ok when driving.

fuel guage , when vehicle is sitting in a slight angle in my driveway will NOT show correct fuel level. I have to turn the vehicle off at a light and then restart to bring level up to correct postion. This is an intermediate problem.

Thanks

misfired
 

Can anyone help me with this problem, the computer diagnose that my 2000 ML320 misfire on #1 and #6, after changed the iginition coil and ingition wire for 1 and 6 the idle still rough and the engine check light still on what could be the problem for misfire code?