97 GLS Sedan with 165000 kms.

Yesterday I filled the fuel tank on my way home from the office. On the highway I was doing 160 km/h and looked at the fuel gauge. It was indicating 70%. WTF?

When I got home and stopped the car, the needle went up to 100%, where it was supposed to be.

Any ideas? Can there possibly be a crack in the fuel tank or fuel line that's screwing up the reading? When I left the gas station there was a very strong gasoline smell in the car which dissappeared when I opened the window on the highway.

Thanks in advance.

I have a 2001 Elantra GT that does the same thing. When I fill up, the gas gauge will move around between the full and 3/4 tank mark. Sometimes after a fill up it goes all the way to full, other times only to 3/4 tank - but I know that the tank is full. Not sure what's causing it, it seems to be accurate once it gets below 3/4 tank. I've heard of other Elantras having this problem also. Sorry not much help, but at least you know you're not the only one.

Strange thing is that it had never happened before. The fuel gauge was always precise.

Past experience leads me to believe you have a bad fuel level sending unit. I have had these issues on 1996 Caravan, 1988 BMW 750, and 1990 BMW 325IC and putting in a new sending unit solved the problems. I am not familiar with the Hyundai sending unit, but on many cars this part is co-located with the fuel pump (and often in the fuel tank0.