I have no previous knowledge of sugar in gas so I can't be of much help, but I have to ask....

How did sugar get in the tank if the gas lid was closed? Are you Positive sugar got in, or was someone setting it up to look like there was?

dunno about a fuel filter, but IIRC there is one and it is in the tank?

Pull the tank off, drain it, see if that filter is in there, after that, DFK what to do next, never had it done to me.