[C320-list] Fuel Gauge Malfunction

[Chris Burti]

It could be the float sticking...they have been known to have the arm bent
and hang on the side of the tank. You have to remove the shelf in the aft
starboard locker then crawl down into the port locker and remove the
six screws holding the float assembly on the top of the tank.  you can
usually verify that it s moving freely or not if you are careful in removing
it without rotating its alignment.

If you are satisfied that it is not a mechanical problem, here is the
electrical test protocol for the sender and the gauge.
**
*Testing Fuel Gauges*



1. Disconnect Pink Sender Wire from Gauge, and turn power ON.
The Fuel Gauge should read ZERO Scale (< Empty)

2. Short the Gauge Sender Terminal to Ground.
The Gauge should read FULL Scale (> Full).

3. Measure resistance of Pink Sender Wire to Ground.
American Floats: 240 Ohms (Empty), 103 Ohms (½ Full), & 33 Ohms (Full)
European Floats: 10 Ohms (Empty), 95 Ohms (Half), & 180 Ohms (Full)
Automotive & other Float Switches may use other resistances such as 0 - 90
Ohm, 73 - 10 Ohm, & etc.

4. Disconnect Pink Wire from Sender on Fuel Tank.

5. Test continuity of Pink Wire.
Zero Ohms from Tank End to Gauge End - If not, repair or replace Wire.

6. Measure Resistance from Sender Terminal (on Tank) to Ground on Tank.
Should read as per (3) above - If not, replace Sender.




On Fri, Oct 2, 2009 at 2:19 AM, David Detrick <dldetrick at live.com> wrote:

> Have a 2004 C 320 whose fuel gauge sometimes stays frozen on "E" after
> starting, and then after running a while, pops up to the correct level of
> fuel in tank. Several questions---
>
>
>
> 1.       What are possible causes-loose wire, bad sender, dirt in gauge,
> etc.?
>
> 2.       How would you fix the problem?
>
> 3.       Could the problem affect the gauge reading properly when it pop to
> a level above "E." In other words, can I trust the gauge?
>
>


-- 
Chris Burti Farmville, NC