Gas gauge again!

[hauser]

I have read through a few of the posts and did not see anything that would help.  Here's what's going on.

I did quite a bit of driving today and noticed my gas/petrol gauge hadn't moved, it was reading full.  Now I'm the type to keep all of our cars topped off in case of an emergency.  The only exception is the wife that lets her car run practically dry.  

I was either getting terrific gas mileage or something was wrong.  While driving home I kept an eye on the gauge and tried to remember how much driving I did on that tank of fuel. I didn't want to run out of gas in the middle of nowhere!

Once home I went to our local Chevron and pumped 13.5 gallons of 93 octane into the tank.  Again no movement from the gauge.  It either reads full if key is turned on or it reads zero with key turned off.

Can someone please tell me whats going on?

1969 280sl 5 spd        1999 ML320          Gainesville,Fl.

[jeffc280sl]

Sounds like the float on the gas level fitting maybe stuck in the up position indicating a full tank.  You can get access to the device through a plug in the center or so of the trunk.  Remove the float device and check to see that it operates mechanically.  Turn the key on and move the float up and down by hand.  Does the dashboard indicator follow movement in the float?

Jeff C.
1970 280SL 4-speed

[hauser]

I know for fact this worked for a long time.  I usually don't pay too much attention to the gas gauge as much as I do temp and oil pressure.  Key on = full tank
           Key off= needle down

1969 280sl 5 spd        1999 ML320          Gainesville,Fl.

[jeffc280sl]

I suggest you remove the gas float device from the gas tank.  Inspect it and manually move the float up and down to see if the reading on the guage corresponds to 1/2 full etc.

Jeff C.
1970 280SL 4-speed

[Benz Dr.]

Take number 4 fuse out before you work around and opened fuel tank. I'd place a rag or something like that over the hole so nothing drps in and no fumes come out.
As per our conversation last night NEVER use a trouble light near an opened gas tank full of fuel. Ever had a light bulb that came loose and the light went out? Put that tiny spark near gas fumes and your light will go out too. PERMANATLY!
A well sealed flash light is OK but make sure everyting is secure inside first.
Remember, work safe. Don't want to say bye to anyone around here...........

Daniel G Caron

[LFrank]

Similar query on this thread: my little orange (red?) light on my gas gauge has stopped functioning (the needle still works however). Surely this is a fuse and not a bulb? (I ain't going behind the dash for this!)

LFrank
Washington DC
65 230 sl - auto
DB334/Hellblau

[Benz Dr.]

There's a light buld in the centre cluster that could be burned out - it only light when the tank is less than 10 liters.
On the bottom of the sending unit there's 2 small contacts that will touch a disc mounted on the bottom side of the float in the sending unit. Sometimes these contacts will get covered with crud and you will need to very caefully clean this area after memoval of the ending unit. Follow all my safety rules!
The disc on the bottom of the float may need cleaning too. Be very careful with the 2 small wires that run on each side of the sending unit ( inside ) they can be broken and can't be fixed by mortal man ( at least not this one )

Daniel G Caron

[hands_aus]

LFrank I see you have a 230SL.
Have you checked the type of sending unit in your car?
There is a huge difference between the 230 and 280 sending units but they both have a contact that causes the light in the gauge to shine.
One other question, is your gauge accurate?

Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[graphic66]

My reserve light would only come on after sitting a long while. It turned out that the labyrinth cannel used to drain out the gauge tube slowly as fuel is used was plugged and it took time to drain down. Also if your thin filament wire is broke it is quite easy to fix. If it broke at the connection point just resolder it in place and then reroute it in its position to tension the wire. I have replaced the wire using corona wire used in copiers that is like tungsten light bulb filament. If anyone needs this done just let me know, I can do it for you or send you some filament as I have a large roll of it. It really is easy, c'mon Doc I bet you could easily be a pro wire solderer. The trick is to solder the wire at the right lenght and then to route it over its mounts, and the tabs you solder to are springy to tension the wire. If you get the lenght wrong just unsolder it and try again. It works real good.

[Ricardo]

That's interesting....I tried to find the right resistance wire, which if I remember correctly is .5 ohms per foot and was unsuccessfull. I tried other wire but that resulted in a permanently full tank. I was told that this type of wire (which has a proper name, that I also forget) was pretty much only used in the automotive industry and generally not available through electronic supply houses. Good to know there is another source.
Ricardo