Are you getting the following message while installing Gapps?
“Insufficient storage space available in System partition. You may want to use a smaller GApps (i.e. Mini Modular GApps),
You need “,file_getprop(“/tmp/gapps.prop”,”free_space_reqd_kb”),” KB system free space.
You only have “, file_getprop(“/tmp/gapps.prop”,”free_system_size_kb”),” KB available.”
This may happen on older phones when you use the standard “stock” Gapps. This is because older phones do not have as much system space.