Flaky Fuel Reserve Light Indicator
 

84 MB300DT: The light comes on intermittently even when the tank is more than half full and on steady when I turn the left. The needle stays point at over half full which is correct. It goes off sometimes when I turn hard to the right. Anything to do with the fuel sender?

Everything to do with the fuel sender; It's where the contact is. Take it out and have a look. It's probably full of crud, and not allowing fuel to get into the tube. There are great posts (search) that describe exactly how to R&R. It's very easy - just be careful with the wires.

Easy Access and Removal - 84 300DT
 

The fuel sender unit is at the rear dash underneath the First Aid Kit. Two screws to remove the FAK box and presto, it's right there. No need to remove the seats.

Unfortunately in my case, the fuel sender unit appears to be the original (nearing 20 years old!) and has never been cleaned nor replaced. While this forum suggest to be careful not to break the connection, one of the three wire lines, the copper one, came loose off its solder point. Well, it’s time for a new one and when installed I hope it stops the Reserve Fuel Light indicator from coming On prematurely (it goes on even if the tank is over half full).:rolleyes:

Mine usually is on when I start the car in the morning and then goes off later as I drive for a while. I think it actually works like it is supposed to but I rarely ever let the fuel level get that low.

VDO Fuel Sender Unit - NET price variation
 

NET pricing variation for an OEM Fuel Sender Unit (VDO) for a 1984 MB300DT (Oct 2003)
MB Dealer Vancouver, BC C$356.80/1.45 = $246
Hope Fung Vancouver, BC C$111.18/1.45 = $76.67
German Star $89.00
Performance Products $132.00
Importec Parts $102

High ($246) and Low ($76.67) = $169.33 difference!! (local taxes and shipping not included)

I had a broken copper wire connection on the old one (original?) and now replaced. I hope it fixes my problem of the Reserve Fuel Light indicator from coming ON even when the tank is more than half full.

Guess where I purchase one;)

As long as "Fung" isn't Canadian for "it works" you should be OK...