  We present new K-band long baseline interferometer observations of three
young stellar objects of the FU Orionis class, V1057 Cyg, V1515 Cyg and Z
CMa-SE, obtained at the Keck Interferometer during its commissioning science
period. The interferometer clearly resolves the source of near-infrared
emission in all three objects. Using simple geometrical models we derive size
scales (0.5-4.5 AU) for this emission. All three objects appear significantly
more resolved than expected from simple models of accretion disks tuned to fit
the broadband optical and infrared spectro-photometry. We explore variations in
the key parameters that are able to lower the predicted visibility amplitudes
to the measured levels, and conclude that accretion disks alone do not
reproduce the spectral energy distributions and K-band visibilities
simultaneously. We conclude that either disk models are inadequate to describe
the near-infrared emission, or additional source components are needed. We
hypothesize that large scale emission (10s of AU) in the interferometer field
of view is responsible for the surprisingly low visibilities. This emission may
arise in scattering by large envelopes believed to surround these objects.
