PL argument max size, and doubt

I was doing some tests to see if I could find a max size for an argument
of type TEXT in a PL/PgSQL function (BTW, which it that limit if it
exists?).

So I made the function to test:

CREATE OR REPLACE FUNCTION datoGrande(TEXT) RETURNS BOOLEAN AS $body$
BEGIN
EXECUTE $ins1$
INSERT INTO funcdatogrande VALUES (default,$ins1$ ||
quote_literal($1) || $ins2$)$ins2$;
IF FOUND THEN
RETURN TRUE;
ELSE
RETURN FALSE;
END IF;
END;
$body$ LANGUAGE 'plpgsql';

What bothers me is that the INSERT passes ok (the data is inserted) but
the function is returning false on any all to it. I hope not to have a
conceptual problem.