So on my L251 I saw some cheap fuel and stopped to fill up, as my fuel gauge was reading just above half. The car wouldn’t take more than 2 litres of fuel. So I had a poke around to see what the problem might be.
The gauge doesn’t return to zero when the ignition is switched off. When manually returning the needle to zero and switching the ignition on, it climbs very slowly and eventually makes it to the halfway point again. The same when I push the needle to full - it drops slowly and eventually evens out at just above halfway.
Playing around with the instrument cluster to diagnose the fuel gauge problem, I noticed the back of the cluster behind the gauge was noticeably warm, so I’m guessing the gauge has short circuited internally or something.
Would I have any options other than just to replace the cluster entirely to get it working again?
Do these cars use a float as part of the sender? Sometime floats can have a small hole and fill a bit with fuel and not raise all the way up because if this.
Well, I uncovered the problem. It was a dodgy petrol pump handle at the petrol station I originally filled up at which caused me to think the gauge was giving me a wrong reading.
Just went on a 300km highway run to near empty and noticed the gauge moving towards empty as normal. Filled up again, it took 26 litres and the gauge now reads full again.
At the original petrol station I even had fuel gushing back out of the filler neck after trying to trickle the fuel in after the pump stopped, so I could have sworn the tank was full.