diff --git a/test/functional/abc-cmdline.py b/test/functional/abc-cmdline.py
--- a/test/functional/abc-cmdline.py
+++ b/test/functional/abc-cmdline.py
@@ -12,8 +12,6 @@
 import re
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
-    start_node,
-    stop_node,
     assert_equal,
     assert_start_raises_init_error
 )
@@ -48,16 +46,16 @@
 
         self.log.info("  Set to twice the default, i.e. %d bytes" %
                       (2 * LEGACY_MAX_BLOCK_SIZE))
-        stop_node(self.nodes[0], 0)
-        self.nodes[0] = start_node(0, self.options.tmpdir, [
-                                   "-excessiveblocksize=%d" % (2 * LEGACY_MAX_BLOCK_SIZE)])
+        self.stop_node(0)
+        self.nodes[0] = self.start_node(0, self.options.tmpdir, [
+                                        "-excessiveblocksize=%d" % (2 * LEGACY_MAX_BLOCK_SIZE)])
         self.check_excessive(2 * LEGACY_MAX_BLOCK_SIZE)
         # Check for EB correctness in the subver string
         self.check_subversion("/Bitcoin ABC:.*\(EB2\.0; .*\)/")
 
         self.log.info("  Attempt to set below legacy limit of 1MB - try %d bytes" %
                       LEGACY_MAX_BLOCK_SIZE)
-        stop_node(self.nodes[0], 0)
+        self.stop_node(0)
         assert_start_raises_init_error(0, self.options.tmpdir, [
                                        "-excessiveblocksize=%d" % LEGACY_MAX_BLOCK_SIZE], 'Error: Excessive block size must be > 1,000,000 bytes (1MB)')
         self.log.info("  Attempt to set below blockmaxsize (mining limit)")
@@ -66,7 +64,7 @@
 
         # Make sure we leave the test with a node running as this is what thee
         # framework expects.
-        self.nodes[0] = start_node(0, self.options.tmpdir, [])
+        self.nodes[0] = self.start_node(0, self.options.tmpdir, [])
 
     def run_test(self):
         # Run tests on -excessiveblocksize option
diff --git a/test/functional/fundrawtransaction.py b/test/functional/fundrawtransaction.py
--- a/test/functional/fundrawtransaction.py
+++ b/test/functional/fundrawtransaction.py
@@ -459,10 +459,10 @@
 
         #
         # locked wallet test
-        self.nodes[1].encryptwallet("test")
         self.stop_node(0)
         self.stop_node(2)
         self.stop_node(3)
+        self.nodes[1].encryptwallet("test")
         self.nodes.pop(1)
 
         self.nodes = self.start_nodes(self.num_nodes, self.options.tmpdir)
diff --git a/test/functional/high_priority_transaction.py b/test/functional/high_priority_transaction.py
--- a/test/functional/high_priority_transaction.py
+++ b/test/functional/high_priority_transaction.py
@@ -79,9 +79,9 @@
         assert_equal(self.nodes[0].getmempoolinfo()['bytes'], mempool_size_pre)
 
         # restart with default blockprioritypercentage
-        stop_nodes(self.nodes)
-        self.nodes = start_nodes(self.num_nodes, self.options.tmpdir,
-                                 [["-limitfreerelay=2"]])
+        self.stop_nodes()
+        self.nodes = self.start_nodes(self.num_nodes, self.options.tmpdir,
+                                      [["-limitfreerelay=2"]])
 
         # second test step: default reserved prio space in block (100K).
         # the mempool size is about 25K this means that all txns will be
diff --git a/test/functional/mempool-accept-txn.py b/test/functional/mempool-accept-txn.py
--- a/test/functional/mempool-accept-txn.py
+++ b/test/functional/mempool-accept-txn.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python3
-# Copyright (c) 2015-2016 The Bitcoin Core developers
 # Copyright (c) 2017 The Bitcoin developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -50,9 +49,9 @@
 
     def setup_network(self):
         self.extra_args = [['-norelaypriority']]
-        self.nodes = start_nodes(self.num_nodes, self.options.tmpdir,
-                                 self.extra_args,
-                                 binary=[self.options.testbinary])
+        self.nodes = self.start_nodes(self.num_nodes, self.options.tmpdir,
+                                      self.extra_args,
+                                      binary=[self.options.testbinary])
 
     def add_options(self, parser):
         super().add_options(parser)
diff --git a/test/functional/net.py b/test/functional/net.py
--- a/test/functional/net.py
+++ b/test/functional/net.py
@@ -14,7 +14,8 @@
     assert_equal,
     assert_raises_jsonrpc,
     connect_nodes_bi,
-    p2p_port)
+    p2p_port,
+)
 
 
 class NetTest(BitcoinTestFramework):
diff --git a/test/functional/p2p-mempool.py b/test/functional/p2p-mempool.py
--- a/test/functional/p2p-mempool.py
+++ b/test/functional/p2p-mempool.py
@@ -13,11 +13,8 @@
     def __init__(self):
         super().__init__()
         self.setup_clean_chain = True
-        self.num_nodes = 2
-
-    def setup_network(self):
-        self.nodes = [start_node(0, self.options.tmpdir, [
-                                 "-peerbloomfilters=0"])]
+        self.num_nodes = 1
+        self.extra_args = [["-peerbloomfilters=0"]]
 
     def run_test(self):
         # connect a mininode
diff --git a/test/functional/rpcnamedargs.py b/test/functional/rpcnamedargs.py
--- a/test/functional/rpcnamedargs.py
+++ b/test/functional/rpcnamedargs.py
@@ -12,8 +12,6 @@
     assert_raises_jsonrpc,
     assert_is_hex_string,
     assert_is_hash_string,
-    start_nodes,
-    connect_nodes_bi,
 )
 
 
diff --git a/test/functional/test_framework/test_framework.py b/test/functional/test_framework/test_framework.py
--- a/test/functional/test_framework/test_framework.py
+++ b/test/functional/test_framework/test_framework.py
@@ -33,10 +33,10 @@
     p2p_port,
     rpc_url,
     set_node_times,
-    start_node,
-    start_nodes,
-    stop_node,
-    stop_nodes,
+    _start_node,
+    _start_nodes,
+    _stop_node,
+    _stop_nodes,
     sync_blocks,
     sync_mempools,
     wait_for_bitcoind_start,
@@ -105,7 +105,7 @@
         extra_args = None
         if hasattr(self, "extra_args"):
             extra_args = self.extra_args
-        self.nodes = start_nodes(
+        self.nodes = _start_nodes(
             self.num_nodes, self.options.tmpdir, extra_args)
 
     def run_test(self):
@@ -232,16 +232,16 @@
     # Public helper methods. These can be accessed by the subclass test scripts.
 
     def start_node(self, i, dirname, extra_args=None, rpchost=None, timewait=None, binary=None, stderr=None):
-        return start_node(i, dirname, extra_args, rpchost, timewait, binary, stderr)
+        return _start_node(i, dirname, extra_args, rpchost, timewait, binary, stderr)
 
     def start_nodes(self, num_nodes, dirname, extra_args=None, rpchost=None, timewait=None, binary=None):
-        return start_nodes(num_nodes, dirname, extra_args, rpchost, timewait, binary)
+        return _start_nodes(num_nodes, dirname, extra_args, rpchost, timewait, binary)
 
     def stop_node(self, num_node):
-        stop_node(self.nodes[num_node], num_node)
+        _stop_node(self.nodes[num_node], num_node)
 
     def stop_nodes(self):
-        stop_nodes(self.nodes)
+        _stop_nodes(self.nodes)
 
     def split_network(self):
         """
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -302,10 +302,11 @@
     return bitcoind_binary
 
 
-def start_node(i, dirname, extra_args=None, rpchost=None, timewait=None, binary=None, stderr=None):
-    """
-    Start a bitcoind and return RPC connection to it.
-    """
+def _start_node(i, dirname, extra_args=None, rpchost=None, timewait=None, binary=None, stderr=None):
+    """Start a bitcoind and return RPC connection to it
+
+    This function should only be called from within test_framework, not by individual test scripts."""
+
     datadir = os.path.join(dirname, "node" + str(i))
     if binary is None:
         binary = locate_bitcoind_binary()
@@ -329,8 +330,8 @@
 def assert_start_raises_init_error(i, dirname, extra_args=None, expected_msg=None):
     with tempfile.SpooledTemporaryFile(max_size=2**16) as log_stderr:
         try:
-            node = start_node(i, dirname, extra_args, stderr=log_stderr)
-            stop_node(node, i)
+            node = _start_node(i, dirname, extra_args, stderr=log_stderr)
+            _stop_node(node, i)
         except Exception as e:
             assert 'bitcoind exited' in str(e)  # node must have shutdown
             if expected_msg is not None:
@@ -347,12 +348,15 @@
             raise AssertionError(assert_msg)
 
 
-def start_nodes(num_nodes, dirname, extra_args=None, rpchost=None, timewait=None, binary=None):
-    """
-    Start multiple bitcoinds, return RPC connections to them
-    """
+def _start_nodes(num_nodes, dirname, extra_args=None, rpchost=None, timewait=None, binary=None):
+    """Start multiple bitcoinds, return RPC connections to them
+
+    This function should only be called from within test_framework, not by individual test scripts."""
+
     if extra_args is None:
         extra_args = [None for _ in range(num_nodes)]
+    if binary is None:
+        binary = [None for _ in range(num_nodes)]
     assert_equal(len(extra_args), num_nodes)
     if binary is None:
         binary = [None for _ in range(num_nodes)]
@@ -360,11 +364,10 @@
     rpcs = []
     try:
         for i in range(num_nodes):
-            rpcs.append(start_node(i, dirname, extra_args[i],
-                                   rpchost, timewait=timewait,
-                                   binary=binary[i]))
+            rpcs.append(_start_node(
+                i, dirname, extra_args[i], rpchost, timewait=timewait, binary=binary[i]))
     except:  # If one node failed to start, stop the others
-        stop_nodes(rpcs)
+        _stop_nodes(rpcs)
         raise
     return rpcs
 
@@ -373,7 +376,11 @@
     return os.path.join(dirname, "node" + str(n_node), "regtest", logname)
 
 
-def stop_node(node, i):
+def _stop_node(node, i):
+    """Stop a bitcoind test node
+
+    This function should only be called from within test_framework, not by individual test scripts."""
+
     logger.debug("Stopping node %d" % i)
     try:
         node.stop()
@@ -385,9 +392,13 @@
     del bitcoind_processes[i]
 
 
-def stop_nodes(nodes):
+def _stop_nodes(nodes):
+    """Stop multiple bitcoind test nodes
+
+    This function should only be called from within test_framework, not by individual test scripts."""
+
     for i, node in enumerate(nodes):
-        stop_node(node, i)
+        _stop_node(node, i)
     assert not bitcoind_processes.values()  # All connections must be gone now
 
 
diff --git a/test/functional/zmq_test.py b/test/functional/zmq_test.py
--- a/test/functional/zmq_test.py
+++ b/test/functional/zmq_test.py
@@ -13,7 +13,6 @@
 from test_framework.util import (
     assert_equal,
     bytes_to_hex_str,
-    start_nodes,
 )