diff --git a/system_tests/pubsub.py b/system_tests/pubsub.py
index 2f3d3295373c..30d0fd5de3d9 100644
--- a/system_tests/pubsub.py
+++ b/system_tests/pubsub.py
@@ -151,6 +151,7 @@ def _all_created(result):
         self.assertEqual(len(created), len(subscriptions_to_create))
 
     def test_message_pull_mode_e2e(self):
+        import operator
         topic = Config.CLIENT.topic(DEFAULT_TOPIC_NAME,
                                     timestamp_messages=True)
         self.assertFalse(topic.exists())
@@ -169,15 +170,24 @@ def test_message_pull_mode_e2e(self):
         topic.publish(MESSAGE_1, extra=EXTRA_1)
         topic.publish(MESSAGE_2, extra=EXTRA_2)
 
-        received = subscription.pull(max_messages=2)
-        ack_ids = [recv[0] for recv in received]
-        subscription.acknowledge(ack_ids)
-        messages = [recv[1] for recv in received]
+        class Hoover(object):
 
-        def _by_timestamp(message):
-            return message.timestamp
+            def __init__(self):
+                self.received = []
 
-        message1, message2 = sorted(messages, key=_by_timestamp)
+            def done(self, *dummy):
+                return len(self.received) == 2
+
+            def suction(self):
+                with subscription.auto_ack(max_messages=2) as ack:
+                    self.received.extend(ack.values())
+
+        hoover = Hoover()
+        retry = RetryInstanceState(hoover.done)
+        retry(hoover.suction)()
+
+        message1, message2 = sorted(hoover.received,
+                                    key=operator.attrgetter('timestamp'))
         self.assertEqual(message1.data, MESSAGE_1)
         self.assertEqual(message1.attributes['extra'], EXTRA_1)
         self.assertEqual(message2.data, MESSAGE_2)
@@ -243,6 +253,7 @@ def test_subscription_iam_policy(self):
             self.assertEqual(new_policy.viewers, policy.viewers)
 
     def test_fetch_delete_subscription_w_deleted_topic(self):
+        from gcloud.iterator import MethodIterator
         TO_DELETE = 'delete-me' + unique_resource_id('-')
         ORPHANED = 'orphaned' + unique_resource_id('-')
         topic = Config.CLIENT.topic(TO_DELETE)
@@ -251,13 +262,15 @@ def test_fetch_delete_subscription_w_deleted_topic(self):
         subscription.create()
         topic.delete()
 
-        all_subs = []
-        token = None
-        while True:
-            subs, token = Config.CLIENT.list_subscriptions(page_token=token)
-            all_subs.extend(subs)
-            if token is None:
-                break
+        def _fetch():
+            return list(MethodIterator(Config.CLIENT.list_subscriptions))
+
+        def _found_orphan(result):
+            names = [subscription.name for subscription in result]
+            return ORPHANED in names
+
+        retry_until_found_orphan = RetryResult(_found_orphan)
+        all_subs = retry_until_found_orphan(_fetch)()
 
         created = [subscription for subscription in all_subs
                    if subscription.name == ORPHANED]
@@ -267,8 +280,9 @@ def test_fetch_delete_subscription_w_deleted_topic(self):
         def _no_topic(instance):
             return instance.topic is None
 
-        retry = RetryInstanceState(_no_topic, max_tries=6)
-        retry(orphaned.reload)()
+        # Wait for the topic to clear: up to 63 seconds (2 ** 6 - 1)
+        retry_until_no_topic = RetryInstanceState(_no_topic, max_tries=7)
+        retry_until_no_topic(orphaned.reload)()
 
         self.assertTrue(orphaned.topic is None)
         orphaned.delete()