2003 E320 Fuel Level Gauge WRONG!! - PeachParts Mercedes-Benz Forum

David C Klasse · #1 02-19-2014, 04:52 AM

After having my fuel sending unit and pump replaced, maybe 2 weeks later, my gas gauge stopped working! I was oblivious and ran outta gas on way to school one am.. and it hasn't been normal ever since! THere was one time where it actually read an entire tank of fuel accurately since the problem began. I try and fill it all the way up, etc, trying to reset it,,,, but nada still.. it always sits between the 1/4 & 3/4 way up.

I do periodically get a CHECK FUEL CAP! message in the display.. so I know that's bad... (I replaced the gasket, but "problem" persists)... maybe I need the entire fuel cap?

Anyway, I've been doing some research.,.. and don't really understand it; this is what came up in the parts catalogue description:

"Don't get caught at the side of the road with an empty tank even though your gauge says full. The fuel tank sender is used to measure the amount of fuel in the fuel tank and send an electrical impulse to the fuel gauge. If your fuel gauge is starting to give incorrect readings, it's possibly this sender."

I do not recall ordering a fuel pump assembly ring when I got the rest of the parts.... could this be my problem? ANd if so, why is it called a SENDER when it merely appears to be a gasket of sorts?

Please, enlighten me.... SOMEBODY!

Thanks. I appreciate any input and valid leads!!

David C Klasse · #2 02-22-2014, 08:49 AM

anybody?

97 SL320 · #3 02-22-2014, 10:05 AM

Do you have any pics / part numbers so we are all talking about the same parts?

Is the 2003 a W210 body? I've had a 97 E320 W210 apart and am familiar with the tank.

David C Klasse · #4 02-22-2014, 02:46 PM

It's the first year of the W211 body (in the US, anyway). It's also the M112 motor, which is the V6 first offered in the US in 1998 on the 320/280 models.
So it is a different motor than your 97 (which the M104 motor).

And I don't know what pix or part numbers you mean?
I had the fuel pump and the fuel pump level sending unit replaced about 5 months ago... sorry, don't have part numbers off hand.

97 SL320 · #5 02-22-2014, 06:41 PM

" I do not recall ordering a fuel pump assembly ring when I got the rest of the parts "

I don't know what part you are referring to.

David C Klasse · #6 02-22-2014, 07:09 PM

" I do not recall ordering a fuel pump assembly ring when I got the rest of the parts "

-WHen did I say this?

ANd the parts I am referrring to are the FUEL PUMP AND FUEL LEVEL SENDING UNIT

Thanks,,,,.

joshuajeeper · #7 02-27-2014, 09:48 PM

If the fuel pump (right side of tank) or the fuel filter (left side of tank) - both with a level sensor - are not "clocked" correctly in relation to the fuel tank then the arm of the level sensor will hangup on the hoses inside the tank preventing it from ever reaching the bottom of the tank. There is a little arrow cast into the top of each assembly and a casting line on the tank that have to line up with each other. If they are off, it sound like the arm of the level sensor is stuck on the lines. (9 times out of 10, if the left side thats the problem). Most of the time this happens after the unit is replaced and installed incorrectly, but I have seen a few times where over time the locking ring loosens up causing the unit to rotate out of place.

David C Klasse · #8 02-27-2014, 11:57 PM

Is this something I can do myself? I'm pretty savvy... but not that competent. Do I have to access this from under the vehicle? Or can it be done from under the rear bench?

joshuajeeper · #9 02-28-2014, 12:20 AM

It is accessible from under the rear seat bench. With the seat cushion out, there are two cover plates (one for each side) with (I think) 6 screws. The left side will have a wiring harness going under it. There are two electrical connectors on top of the left side assembly with one fuel line going to it. There is a special tool thats needed to remove (and properly torque!) the locking ring that holds the assembly down. To remove the assembly, you will have to open up the right side as well to disconnect the hoses that run from the left side to the right. The hoses are apart of the left side unit and not to be removed separately. You will see on top of each assembly the arrow I was talking about, just make sure it is lined up with the mark on the tank. Also, you will need a new hose clamp for the line (don't use anything other than the quick clamp style, otherwise the hose can be damaged by a worn drive clamp - I've seen it numerous times!!) and new seals for both left and right side.

Lastly, if everything is lined up before removal - it most likely is a level sensor fault. However, both sides have a level sensor and it could be either or. So, some diagnosis would be required.

David C Klasse · #10 02-28-2014, 04:24 AM

THanks a bunch!
I'm going to take your post and print a copy and bring it down to my mechanic who replaced the fuel pump.

Also, would lack of fuel pressure have ANYTHING toi do with this issue? Or the periodic hesitation? or shoot straight towards testing TPS, etc?

Thanks again!! I really appreciate it.

97 SL320 · #11 02-28-2014, 08:03 PM

Quote:

Originally Posted by David C Klasse

" I do not recall ordering a fuel pump assembly ring when I got the rest of the parts "

-WHen did I say this?

ANd the parts I am referrring to are the FUEL PUMP AND FUEL LEVEL SENDING UNIT

Thanks,,,,.

Read the last quarter of your first post. Also, no need to yell.

David C Klasse · #12 02-28-2014, 08:46 PM

Not yellling, just emphasizing the parts ordered/replaced.

So I'm not sure I follow what you're saying.... I do have a brass-colored (metal) o-ring in packaging still... thought it came with my oil filler set... but I could be wrong.

..THanks