Bilrich19288, welcome to Just Answer!.
You've nailed it. It's in the tank. When it acts up at a particular tank level, it's because your tank level unit is spending the majority of its time in the bad spot of the potentiometer card. Knowing that it is pretty much OK above this level pretty much seals the deal... you need a new level unit.
The mid-range of the reader card is the most used portion of the level unit in most vehicles. High tank levels only last so long and don't have the same amount of float arm movement from fuel slosh that the mid ranges do. Chances are good that the problem may be somewhat less active at lower tank levels as well if you tend to keep 1/4 tank or more in the van at all times.
I'm afraid there isn't a way to turn the chime off. It's going to continue to haunt you until the level unit (or fuel pump module, complete) is replaced.
Write back if you have any questions.
Hi Brich. The level unit runs around $70 and labor should be no more than 1.5 hours of shop time (whatever that happens to be in your neighborhood). That puts it around $300 at the outside.
There might be an extra fuel transfer fee if the tank is above 1/2, so try to see that it's closer to empty than not.
If the fuel pump has more than 100,000 miles on it you might consider replacing the pump module as a unit if you're going to keep the van for a few more years. The half-life of the pump is around that point, so it might pay off to just do the whole thing as a unit and get it over with.
The fuel filter is an in-line unit on your 1999 Caravan, something that's somewhat of a rarity these days. You might consider replacing it if it hasn't been done in the last 50K miles whether you get the new pump or not. It sits above the tank, so this would be an ideal opportunity to get it done at a reduced labor cost.