Dear friends:

The fuel gauge light on my friend's W116 300SD (1980) comes up frequently even if the fuel tank is full. The fuel gauge needle does correctly show the remaining fuel in the tank, but the light is on most of the time. It seems that the fuel light has something to do with the seat belt circuit because yanking the driver seat belt may cause the fuel light to be on or off sometimes. What's the most common cause for this problem? Thanks.

Best regards,

Eric

I am not familiar with this model MB, but it sounds like the seatbelt light in the instrument panel has been put into the wrong hole in the cluster (the fuel low position)
IIRC, the low fuel li a contact in the tank sender which can only close the circuit if the float gets to a low fuel level.
Please educate me if I am in error.

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

Dear Tony,

No, the problem only happens recently. The seat belt thing is only my random observation of the problem.

Eric

My 1980 SD's light has been on for the last few days. Havn't had a chance to chase it down yet, but will report what I find when I do.

__________________
1980 300SD Manganese Brown Metallic Clearcoat 248k
1979 300SD White 148 k
1984 300D Silver project car for daughter
1982 300D wrecked
1980 300SD 310K not running

Must be a uniquely 1980 300SD thing, my 1979 300SD has no low fuel light on it.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Sounds like you're having an intermittant short to ground somewhere... could be in the fuel sender, could be anywhere else. Don't know what to tell you to troubleshot... good luck with it!!!

BHDR... both of my '79 300SD's have low fuel lights. You must have a special one

John
'79 300SD

Thanks to all for your suggestion.

Dear jdblann: if you find out the problem, please post it here. I've been too busy lately and don't have time to mess around with cars. Thanks in advance.

Best regards,

Eric

Can't think its special at all, but I will look at it again tomorrow, been driving this for about 17 months now and never noticed it before. But then I never ran it very close to empty before either.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

The low fuel light is in the gauge of my 300D, shows as a triangle in amber when the "ignition" key (don't flame me please) is turned on, before the engine is running.
Yours may have a blown globe or broken wire.

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

You kown what, I found it. Year and a half with this car and I never noticed it before. A small triangle on the left of the fuel guage, I need to pull the cluster and check the bulb, it has never come on with the key. And I never ran the car low enough on fuel for it to come on that way.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Chances are that if it doesn't come on with the key before start, that it won't come on when fuel is low . Most likely it's just a blown bulb or some corrosion on it's contacts.