Hi. I have an erratic fuel gauge on my ’97 C280. Nothing new there, I know.

When searching this topic, I find a lot of discussion about it, but no one has mentioned exactly how to get to it. Can it be accessed from the trunk, under the car, or do I have to drop the tank?

Anyone done this before? Thanks in advance.

ON The C-class there are 2 fuel tank sending units wired in series. Under the car on each side of the fuel tank. Resistance values should be between 5 ohms & 98 ohms EACH

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Thank you. Does this mean that the actual sending units are visible/accessable undereath, or that I must drop the tank to reach them? Been told that this takes special MBZ tools to do so.

The Fuel sending units are accessable..With the car on a Lift
There are Plastic covers on Each Side of the Tank That Will Expose the Fuel level sending units...MB Makes a Factory tool to remove the Metal Ring that secures the sending unit to the tank
But You can Remove them without the tool...Just takes Longer
Also Please Make sure that The Fuel tank is Drained BEFORE you try to remove the fuel level sendings.....

I Have Done Several Of the Sending Units on Most all Late MBs

I have the same problem on my 99 ML430. Is the fuel sender accesible from the vehicle or do I have to drop the fuel tank?
Thanks.

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Josemin


88 MB 300E
88 MB 560SEL
99 MB ML 430

Thanks again. Yes, I will make sure the tank is empty. It'll likely happen soon since the gauge doesn't work. But if I can't wait, I'll just drill a hole in the bottom of the tank and run the gas into a bucket. Of course, it's a little hard to do that when I am laying under the car on my back, holding a drill in one hand and trying to light my cigar with the other. But I'll get it done somehow.

ML is another Story...

I Did It on my EX My Twice.....
You Wont want to try this at home...
Have the Dealer GOODWILL It! its a Known Problem-





Rprosser

You Forgot the Open wire extension cord and The Very Hot 110
watt lamp for the shop lite next to the Cigar and The Guy Welding on the Rear Muffler

EPineda:
The ML fuel sender/fuel pump assembly is accesable through an access hole under the left side of the rear seat. The seat is removed and the carpet can be pulled up, and there is a metal cover on the floor which is sealed with body sealer. I use a hot air gun to soften the sealer, then pry it up with a gasket scraper.
The top ring which holds down the sender/pump unit is then removed with a special MB tool, it would be difficult to remove the ring without this tool on the ML especially.

RProsser:
There is a defuel procedure available for the C Class, I would recommend, if you need to remove a sender, in doing it correctly.
There is a defuel hose which attaches to the right sender unit, then a special fuel cap with a hose attached. Compressed air is introduced into the fuel cap with hose, and this will allow fuel to begin flowing out of the defuel hose and into a fuel caddy or a large fuel can.

Gilly

Gilly, sorry to jump in, but on the subject of defueling, how do I do it on an 88 300CE? Thanks.
Rich

Rich
No problem.
There are several ways to defuel it, mostly it would be best to do these in a shop.
To start with I'd defuel it using a fuel caddy. It's pretty easy to do on a 124 chassis, the defuel (suction) hose lays down into the tank pretty well.
You can also choose to run the tank nearly dry just by driving it, and letting the fuel pump get the rest of it out, or just pull the supply line from the tank to the pump off and let it run into the top of the caddy using a large funnel (this is the fastest way, but lots of fumes and almost requires the car to be on the hoist).
The fumes never bothered me much, maybe that's why I am like I am .
<<
With the 124 and other cars with out-of-the-tank pumps it opens up different options like this. With the 202 you are limited because of the "saddle" tank design.
Why do you need to defuel it, BTW? The sender unit goes in from the trunk and you'd be safe removing it if you are down to about 1/2 a tank.

Gilly

Gilly, one of my teenagers ran out of gas in the 889 300ce because the fuel sender did its usual acting up job, & now the car is hard to start & stalls virtually immediately, which it never did before. I'm figuring clogged fuel filter, & so I wanted to drain the tank to swap the fuel filter/pump/accumulator assembly from a previously great 1991 300e (now a parts car, front end totaled by my other teenager) to the 88 300ce. From what I have read during my search, I thought it was necessary to drain the fuel tank to do this. (I'm also going to check the fuel pump relay tonight since that would be a much easier fix.)
Rich

Rich
You can go to Sears or an auto store and buy one of these clamps (like a pliers except it ratchets shut and has flat jaws) to pinch off the fuel supply line and then do your work.

Gilly

Gilly,

Is that type of clamp tool similar to the one I once saw an MB tech use on the coolant hoses when he changed my thermostat? If so, then it would have another valuable use & be an excellent addition for those of us who don't have one (although someone here has suggested using popsicle sticks held together by a visegrip).

One last question, please. The gas tank on the old car has two nasty rust bubbles, & since I am afraid sanding/wire brushing might create a hole I am considering swapping the tank with that from the 91 300e. In addition to the bolts (4?) in the trunk on the sides of the tank, what would I do to remove it? Thanks, & sorry to digress in this thread (I couldn't find any removal info by searching).

Rich

Rich:
Other than the 4 nuts, you obviously have get the trunk trim out of the way. You'll also see the connector for the fuel gauge sender unit.
Under the car you need to remove all the hoses.
That's about it, maybe go ahead and push the grommet around the fuel filler neck into the car body (leave it on the neck).
I'd also recommend removing the spare and the cover over the spare (trunk floor trim) and putting some old towel down in case some of the fuel is left in the tank and decides to run out when you remove the tank.

Gilly

PS yes, the tool you saw being used on the coolant hose is probably the same tool I am talking about.
Also the main fuel feed hose, from the bottom of the tank to the filter and pump assembly often needs to be removed from the bottom of the tank to be able to easily remove the tank.

Thanks, Gilly, as always.
Regards
Rich