Fuel Sending Unit Location; I'm New Here - PeachParts Mercedes-Benz Forum

ttapley · #1 03-11-2007, 11:30 AM

Hello Out There. I Just Bought A 1976 240d And It Has Already Captured My Complete Attention. My Gas Guage And My Water Temp Gauge Bounce Around Like There Is No Tommorrow. I Know I Should Replace The Respective Sending Units For The Two Gauges But Don't Know Where They Are. If Anyone Could Help Me Out It Would Be Greatley Aprreciated.

vox_incognita · #2 03-11-2007, 12:42 PM

#125,this is how it looks like:

First check witha ohmmeter whether the resistance is erratick,clean the contact points also9could be bad ground)

#20,fuel unit sender...it`s in the trunk compartment
[IMG]http://www.***************/secure/PartImages/1105421204.jpg[/IMG]
Also clean and check resistance...full tank appr. 4,5ohm,empty appr. 66ohm(this have to be confirmed,I`m not 100% sure)
http://www.kienzle.de/uploads/media/sensoren_instrumentierung.pdf

This here is w116,but have a look(operation principle same):
http://handbook.w116.org/Engine/617/47-715.pdf
http://handbook.w116.org/Engine/617/47-710.pdf
Good Luck!

carnut · #3 03-11-2007, 01:24 PM

Both gauges bouncing around is usually caused by a loose connection at the back of the gauge cluster or a poor ground to the cluster. Remove the cluster and make sure the multi wire connector on the back is fully seated in the circuit board. Also with the cluster out you will see many brown wires (ground wires) secured to the dash brace. Make sure they are tight as well. Do a "SEARCH" for removing the cluster. Try www.dieselgiant.com for his post on odometer repair. It shows removal of the speedo cluster.

toomany MBZ · #4 03-11-2007, 02:56 PM

Agree with carnut, I had two different fuel gauge problems, neither jumped around, just inaccurate readings, as I found out on the SD 3:30am Christmas morning...on the interstate. The fella I bought the 240 from [since sold] informed me about gauge, replaced it problem solved. I refer to that car as the bio hazard. The SD fuel in it when I bought it was red, indicating farm use. BTW the diagram of the fuel tank in a previous post, looks to be from a TD, as it is horizontal. To access sending unit in tank, remove first aid kit, you'll see it. Yet an electrical problem would seem likely.

Stevo · #5 03-11-2007, 08:56 PM

Quote:

Originally Posted by toomany MBZ

Agree with carnut, I had two different fuel gauge problems, neither jumped around, just inaccurate readings, as I found out on the SD 3:30am Christmas morning...on the interstate. The fella I bought the 240 from [since sold] informed me about gauge, replaced it problem solved. I refer to that car as the bio hazard. The SD fuel in it when I bought it was red, indicating farm use. BTW the diagram of the fuel tank in a previous post, looks to be from a TD, as it is horizontal. To access sending unit in tank, remove first aid kit, you'll see it. Yet an electrical problem would seem likely.

He has a 115, I was wondering about that fuel tank too, TD, or is that the way the tanks are in the 115?

meltedpanda · #6 03-12-2007, 02:58 PM

W115 accesed through opening in trunk, under mat

Stevo · #7 03-12-2007, 04:18 PM

Ah, OK, thanks...altogather different than the W123 then.

toomany MBZ · #8 03-12-2007, 04:38 PM

Quote:

Originally Posted by Stevo

He has a 115, I was wondering about that fuel tank too, TD, or is that the way the tanks are in the 115?

Ah so.

dabenz · #9 03-12-2007, 07:32 PM

ttapley, chase the grounds behind the dash first. Should clear up the jumpy temperature gauge. If it does and the fuel gauge is still jumpy or steady and a big jump when driving or filling then you have gunk in your fuel tank (and sender). You can fish a piece of garden hose through the filler neck (if behind the license plate) and bang it free, but you'll still need to clean the tank. A search will find lots of ways to do it - remember to carry a few spare fuel filters.