fuel tank problem - PeachParts Mercedes-Benz Forum

TheDon · #1 02-20-2006, 12:45 PM

ok here is the skinny

i put 6 gallons of D2 in yesturday .and raised the level from almost on reserve to almost half full

drove 80 miles and its down to 1/4 the capacity of the tank is 21 US gallons

shoudnt the 6 gallons i put in not of registered at half tank? unless im not doing my math correct

i can tell you that the tank has a vacuum on it because when i go open the filer cap air rushes in. i need to unclog the vent i suppose if that is causing the problem.. could my tank have a dent in it perhaps? is the only way of making sure is by un hooking all the fuel lines with an empty tank and visually inspecting the tank . and i think i need to turn the alda back a little

**just tried to move the alda back a little and .. i uhh broke the set screw.. wonderful o very wonderful. no other change.. why cant diesel go back down to 1.20.. why o why. damn arabs***

Hatterasguy · #2 02-20-2006, 05:14 PM

Its an old fuel guage it isn't going to be spot on. Reset the trip odo figure out your fuel mileage and calculate your range based on that.

mdisav · #3 02-21-2006, 08:48 AM

I thought it was more like 18 or 19. I was remembering reading 15.9 with a 2.9 reserve?

signalredcoupe · #4 02-21-2006, 09:44 AM

On most all fuel tanks, the sender will always read less fuel between empty & half, than half to full. It gives a false sense of mileage. You seem to be able to drive many miles before the needle even begins to move off of full. The resistance change of the fuel sender is not consistent throughout its range.
I'm guessing a true half of tank will be shown with the needle between 1/2 & 3/4. Paul.

__________________
'84 300CD 290,000

Habanero · #5 02-21-2006, 02:40 PM

Quote:

Originally Posted by signalredcoupe

On most all fuel tanks, the sender will always read less fuel between empty & half, than half to full. It gives a false sense of mileage. You seem to be able to drive many miles before the needle even begins to move off of full. The resistance change of the fuel sender is not consistent throughout its range.
I'm guessing a true half of tank will be shown with the needle between 1/2 & 3/4. Paul.

__________________
'84 300CD 290,000

What you describe fits with my experience perfectly. I've seen the same thing in every vehicle I've ever owned.

I've noticed fuel temperature plays a small role in where the gauge reads as well. I don't see it so much in the Mercedes, but I know in my truck you can always count on the gauge being slightly lower the next morning compared to what it was the night before. The Duramax returns a ton of fuel and the tank temp gets pretty warm, and of course temperature is going to play a role in wire resistance.