This study considers the level of occurrence of nonlinear wave-wave interactions in foreshock nonthermal plasma and whether such interactions are significant in producing observed electromagnetic emissions. To this end, we performed two-dimensional electromagnetic particle-in-cell (PIC) simulations using the time-of-flight electron distribution model described in the paper proceeding this [Yin et al., this issue>, and input parameters based on two sets of Wind/3DP distribution measurements made when narrowband and broadband waves were detected by the Wind/WAVES instruments. In the simulations we limited the wave energy density to W≲10-3, a value inferred from the largest wave amplitude detected by Wind. We consider the dynamics of narrowband and broadband wave instabilities, focusing on wave-coupling processes in the presence of foreshock hot ions as well as the most intense narrowband waves, which are the most likely candidates for producing the detected electromagnetic emissions. Results are compared with recent Wind measurements. We showed that when foreshock conditions exist, quasilinear diffusion dominates the instabilities, that weak wave coupling does not prevent beam flattening, and that no discernible wave backscattering occurs. The study indicates that the weak nonlinearity of foreshock electrostatic waves in a homogeneous plasma and in the presence of foreshock nonthermal electrons and moderate beam parameters is not responsible for the generation of electromagnetic emissions at either the fundamental or the second harmonic of the plasma frequency. ¿ 1998 American Geophysical Union