diff --git a/libraries/AP_GPS/AP_GPS.cpp b/libraries/AP_GPS/AP_GPS.cpp
index 6116ca2500..774bc6109b 100644
--- a/libraries/AP_GPS/AP_GPS.cpp
+++ b/libraries/AP_GPS/AP_GPS.cpp
@@ -498,7 +498,7 @@ AP_GPS::update_instance(uint8_t instance)
     // has expired, re-initialise the GPS. This will cause GPS
     // detection to run again
     if (!result) {
-        if (tnow - timing[instance].last_message_time_ms > 2000) {
+        if (tnow - timing[instance].last_message_time_ms > 4000) {
             // free the driver before we run the next detection, so we
             // don't end up with two allocated at any time
             delete drivers[instance];
diff --git a/libraries/AP_GPS/AP_GPS_UBLOX.cpp b/libraries/AP_GPS/AP_GPS_UBLOX.cpp
index 24cbc0b262..2374590381 100644
--- a/libraries/AP_GPS/AP_GPS_UBLOX.cpp
+++ b/libraries/AP_GPS/AP_GPS_UBLOX.cpp
@@ -105,7 +105,9 @@ AP_GPS_UBLOX::_request_next_config(void)
     case STEP_POLL_SVINFO:
         // not required once we know what generation we are on
         if(_hardware_generation == 0) {
-            _send_message(CLASS_NAV, MSG_NAV_SVINFO, 0, 0);
+            if (!_send_message(CLASS_NAV, MSG_NAV_SVINFO, 0, 0)) {
+                _next_message--;
+            }
         }
         break;
     case STEP_POLL_SBAS:
@@ -116,13 +118,19 @@ AP_GPS_UBLOX::_request_next_config(void)
         }
         break;
     case STEP_POLL_NAV:
-        _send_message(CLASS_CFG, MSG_CFG_NAV_SETTINGS, nullptr, 0);
+        if (!_send_message(CLASS_CFG, MSG_CFG_NAV_SETTINGS, nullptr, 0)) {
+            _next_message--;
+        }
         break;
     case STEP_POLL_GNSS:
-        _send_message(CLASS_CFG, MSG_CFG_GNSS, nullptr, 0);
+        if (!_send_message(CLASS_CFG, MSG_CFG_GNSS, nullptr, 0)) {
+            _next_message--;
+        }
         break;
     case STEP_NAV_RATE:
-        _send_message(CLASS_CFG, MSG_CFG_RATE, nullptr, 0);
+        if (!_send_message(CLASS_CFG, MSG_CFG_RATE, nullptr, 0)) {
+            _next_message--;
+        }
         break;
     case STEP_POSLLH:
         if(!_request_message_rate(CLASS_NAV, MSG_POSLLH)) {
@@ -345,7 +353,11 @@ AP_GPS_UBLOX::read(void)
         _request_next_config();
         _last_config_time = millis_now;
         if (_unconfigured_messages) { // send the updates faster until fully configured
-            _delay_time = 750;
+            if (!havePvtMsg && (_unconfigured_messages & CONFIG_REQUIRED_INITIAL)) {
+                _delay_time = 300;
+            } else {
+                _delay_time = 750;
+            }
         } else {
             _delay_time = 2000;
         }
@@ -1102,9 +1114,12 @@ AP_GPS_UBLOX::_update_checksum(uint8_t *data, uint16_t len, uint8_t &ck_a, uint8
 /*
  *  send a ublox message
  */
-void
+bool
 AP_GPS_UBLOX::_send_message(uint8_t msg_class, uint8_t msg_id, void *msg, uint16_t size)
 {
+    if (port->txspace() < (sizeof(struct ubx_header) + 2 + size)) {
+        return false;
+    }
     struct ubx_header header;
     uint8_t ck_a=0, ck_b=0;
     header.preamble1 = PREAMBLE1;
@@ -1120,6 +1135,7 @@ AP_GPS_UBLOX::_send_message(uint8_t msg_class, uint8_t msg_id, void *msg, uint16
     port->write((const uint8_t *)msg, size);
     port->write((const uint8_t *)&ck_a, 1);
     port->write((const uint8_t *)&ck_b, 1);
+    return true;
 }
 
 /*
@@ -1139,8 +1155,7 @@ AP_GPS_UBLOX::_request_message_rate(uint8_t msg_class, uint8_t msg_id)
         struct ubx_cfg_msg msg;
         msg.msg_class = msg_class;
         msg.msg_id    = msg_id;
-        _send_message(CLASS_CFG, MSG_CFG_MSG, &msg, sizeof(msg));
-        return true;
+        return _send_message(CLASS_CFG, MSG_CFG_MSG, &msg, sizeof(msg));
     }
 }
 
@@ -1159,8 +1174,7 @@ AP_GPS_UBLOX::_configure_message_rate(uint8_t msg_class, uint8_t msg_id, uint8_t
     msg.msg_class = msg_class;
     msg.msg_id    = msg_id;
     msg.rate      = rate;
-    _send_message(CLASS_CFG, MSG_CFG_MSG, &msg, sizeof(msg));
-    return true;
+    return _send_message(CLASS_CFG, MSG_CFG_MSG, &msg, sizeof(msg));
 }
 
 /*
diff --git a/libraries/AP_GPS/AP_GPS_UBLOX.h b/libraries/AP_GPS/AP_GPS_UBLOX.h
index cfbe13ddf4..b67d9f0954 100644
--- a/libraries/AP_GPS/AP_GPS_UBLOX.h
+++ b/libraries/AP_GPS/AP_GPS_UBLOX.h
@@ -74,6 +74,8 @@
 #define CONFIG_SBAS          (1<<12)
 #define CONFIG_RATE_PVT      (1<<13)
 
+#define CONFIG_REQUIRED_INITIAL (CONFIG_RATE_NAV | CONFIG_RATE_POSLLH | CONFIG_RATE_STATUS | CONFIG_RATE_VELNED)
+
 #define CONFIG_ALL (CONFIG_RATE_NAV | CONFIG_RATE_POSLLH | CONFIG_RATE_STATUS | CONFIG_RATE_SOL | CONFIG_RATE_VELNED \
                     | CONFIG_RATE_DOP | CONFIG_RATE_MON_HW | CONFIG_RATE_MON_HW2 | CONFIG_RATE_RAW | CONFIG_VERSION \
                     | CONFIG_NAV_SETTINGS | CONFIG_GNSS | CONFIG_SBAS)
@@ -476,16 +478,16 @@ private:
 
     enum config_step {
         STEP_PVT = 0,
+        STEP_NAV_RATE, // poll NAV rate
         STEP_SOL,
         STEP_PORT,
-        STEP_POSLLH,
         STEP_STATUS,
+        STEP_POSLLH,
         STEP_VELNED,
         STEP_POLL_SVINFO, // poll svinfo
         STEP_POLL_SBAS, // poll SBAS
         STEP_POLL_NAV, // poll NAV settings
         STEP_POLL_GNSS, // poll GNSS
-        STEP_NAV_RATE, // poll NAV rate
         STEP_DOP,
         STEP_MON_HW,
         STEP_MON_HW2,
@@ -544,7 +546,7 @@ private:
     void        _configure_rate(void);
     void        _configure_sbas(bool enable);
     void        _update_checksum(uint8_t *data, uint16_t len, uint8_t &ck_a, uint8_t &ck_b);
-    void        _send_message(uint8_t msg_class, uint8_t msg_id, void *msg, uint16_t size);
+    bool        _send_message(uint8_t msg_class, uint8_t msg_id, void *msg, uint16_t size);
     void	send_next_rate_update(void);
     bool        _request_message_rate(uint8_t msg_class, uint8_t msg_id);
     void        _request_next_config(void);