Attempting to copy/paste a 159KB TSQL query into Microsoft Access 2010 passthrough query editor (to a Microsoft SQL Server 2008 backend).
This produces pop-up error,
The help file says that the maximum number of characters in a SQL statement is approximately 64,000. It doesn't mention any difference between pass through queries and other queries, so in the absence of any specific documentation I'm assuming that this also applies to pass through queries.
Looking for this myself and found another limitation that is more likely to be your problem as well as mine:
Maximum number of JOINS in a query: 16
Maximum number of nested queries: 50