fuel guage

[humpty]

iam an owner of a 1996 c180 and have a problem with the fuel guage showing full then empty then back upto full does anyone have any ideas how to solve the promlem

 

[turnipsock]

When it jumps to empty it's an open circuit somewhere. It may be the sender unit or a wire somewhere.

Does warning light work correctly?

When it jumps to Full, is the tank actually Full?

 

[humpty]

thankyou for reply the tank can be full or empty it doesnt make any difference and the fuel light does work when tank gets low i have been told it may be sender could you tell me where this can be located as i have looked in boot and under seat but to no avail

 

[turnipsock]

I'm not sure how to get to the sender on your model. It will be on the top of the tank though.

If the gauge only ever shows 'Full' or 'Empty' is sounds like there is a wire of somewhere and it's grounding sometimes.

 

[humpty]

thankyou very much

 

[tom7035]

i have been told it may be sender could you tell me where this can be located as i have looked in boot and under seat but to no avail

You have two sender units (the tank is in two halves), each one located at the lower front of each half of the fuel tank, accessible from underneath the car. There is a bolted-on cover over each one. Their position on the lower part of the tank of course means the tank must be empty (or as near as dammit) before removing. When removing the left-hand sender unit, you will have to disconnect the internal pipes connecting both sections of the tank.

 

[jimsinessex]

Is the problem persistent or just an occasional annoyance?
My 6 yr old CLK started doing this when 2 yrs old (I yr warranty then) but would show corrct level after about 70 miles. after a few times the prob disappeared for months, then re-appeared off and on, not "on" often enough to spend money on it!
The car is now at 120k miles and rarely suffers the problem,
Just set the trip mileometer to zero each time you brim the tank as a back-up and save your cash until the fault becomes persistent.
Previous threads on this subject blame supermarket petrol for corroding the sensor, my experience suggests the problem may in fact be a deposit which can clear itself.
Cheers, Jim

 

[jberks]

The tank sender on the C class is a known weak spot. Lots have been replaced over the years.

 

[humpty]

You have two sender units (the tank is in two halves), each one located at the lower front of each half of the fuel tank, accessible from underneath the car. There is a bolted-on cover over each one. Their position on the lower part of the tank of course means the tank must be empty (or as near as dammit) before removing. When removing the left-hand sender unit, you will have to disconnect the internal pipes connecting both sections of the tank.

thankyou very much this as been a good help

 

[ONEMERC]

I had exactly the same problem on my CLK and had heard the stories about supermarket fuel, so I tried a couple of tankfulls of Super Unleaded and the problem went away and has been fine since. I've mentioned it to a couple of techies since and they say that it's not possible - but as far as I'm concerned the proof of the pudding etc. etc. Using Super Unleaded does not seem to make any difference to the cars running and costs a couple of quid extra a tank - but its better than the £500+ quoted for supplying and fitting new fuel sensors!!! - give it a try1