Take the trans dipstick and drop it down the tank.
Spin it a few times. Pull it out and check it. The
end of the fill tube has a screen on it. (aka sock)
If someone dumped a solid down the filltube you will see
it on the stick. If you have allready fueled up dont do the test.
It would be a waste of time as you would flush what ever it could have been
in the fill tube.

.02
I doubt its sugar. But you never know.

Bill