Lying Fuel Gauge
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Joined: Jun 2006
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Lying Fuel Gauge
Greetings all. I picked up a '99 e300td with 83K miles two weeks ago. I purchased the car with a few deferred maint issues (fuel leaks) and negotiated the price accordingly. The fuel leaks have been repaired and my bride and I took our first trip this weekend. Very nice "touring" car particularly on the open freeway and on a winding road next to a lake.
I filled the tank before we left. Within 35 miles, my almost at full fuel gauge dropped very quickly to just above 3/4s tank and then slightly more slowly worked down to a few ticks below 3/4s. Given the fuel gauge readings, I thought I still had a fuel leak because assuming 5 gallons per quarter tank, the gauge acted as if I had burned through about 7 gallons. On the way home I refilled it (same pump at the same station)just to see exactly how much fuel I had used. We had travelled 130 miles and it only took 3.4 gallons, which is the fuel mileage I expected. Why is the gauge dropping to 3/4 within 30 miles and well below 3/4s at 130 miles. Is there a way to recalibrate these things? Is it the fuel sending unit? The fuel gauge itself? Any BTDTs?
TIA for your collective help and wisdom.
I filled the tank before we left. Within 35 miles, my almost at full fuel gauge dropped very quickly to just above 3/4s tank and then slightly more slowly worked down to a few ticks below 3/4s. Given the fuel gauge readings, I thought I still had a fuel leak because assuming 5 gallons per quarter tank, the gauge acted as if I had burned through about 7 gallons. On the way home I refilled it (same pump at the same station)just to see exactly how much fuel I had used. We had travelled 130 miles and it only took 3.4 gallons, which is the fuel mileage I expected. Why is the gauge dropping to 3/4 within 30 miles and well below 3/4s at 130 miles. Is there a way to recalibrate these things? Is it the fuel sending unit? The fuel gauge itself? Any BTDTs?
TIA for your collective help and wisdom.
Super Member
Joined: Sep 2004
Posts: 551
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From: Virginia
2005 Carlsson CD32 E320 CDI Inline-6
Diesel foams a lot when pumping.
Try filling tank slowly, then let set a few minutes (good time to go into gas station and get a donut or something) then top off again, slowly.
If you have ever tried to put diesel in a 5 gallon can, you'll see what I mean by the foaming. Initially, you can only get about 4 gallons in, then fill when the foam settles down.
If you have ever tried to put diesel in a 5 gallon can, you'll see what I mean by the foaming. Initially, you can only get about 4 gallons in, then fill when the foam settles down.
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Joined: Jun 2006
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Followed cdiken's advice
I took the e300td into a MB dealer today to have the rust campaign done. While there, I had them check out the fuel gauge ("FG") issue. For $50 bucks they plugged into my car, read all of the error codes and cleared them. Their explination was that at some time in the past, the car battery had gotten so low that various items in the car were not talking to each other as they should, tons of error codes were generated and this probably helped the FG to go on the fritz. The say they fixed it. My very next stop was a filling station where I followed cdiken's advice a little to closely. At the end, I filled up so slowly that I managed to bypass the autoshut off on the pump and left about a pint on the ground. Very embarrasing but the fuel station folks were very nice about it. In any event, the FG is now beyond full (I've not seen it there before). Am going on a scout camping trip tomorrow and will put a few hundred miles on the car. I will be very interested to see how many miles we go when the FG reads 3/4s and I will report back. Cdiken -- thanks for your help.
