Troubleshooting Teleflex Speedometer Gauges
Technical Reference Manual
Speedometer (Electric Paddle Wheel Type)
- The Competition Speedometer is not included
in this trouble shooting guide (call Tech Service
941-907-1000 for assistance).
- Check all wire connections to see that they are
tight and not corroded.
- Be sure the ring terminals supplied for the three
sender wires at the gauge end are crimped to
bare wire and making good contact (see Fig. 1).
- When speedometer is first turned on,
the pointer must go to zero. If not, check
connections - ground "G" and ignition "I" wires.
- Voltage at "I" to "G" terminals should be 12-16
- If spinning the sender paddle wheel does not
produce speedometer movement, the system
can be checked to see what component is
not working by doing one of the following:
- If you have a tachometer, first remove 3 sender
wires from the speedometer, remove tach's
gray sender wire and attach to "S" terminal of
speedometer. Start engine. If the speedometer
pointer gives a reading, the paddlewheel
sender was probably not sending a signal to the
speedo and is not working.
- If you have a volt/ohmmeter, connect its leads
to the "G" and "S" terminals of the speedo.
Turn power to speedometer "ON" and rotate
paddlewheel slowly. Voltmeter should show
pulsing DC: 12 volts, 0 volts, 12 volts, etc. as
paddlewheel rotates. If not, the paddlewheel is
- Reconnect in the original manner.
- Be certain the paddle wheel is snapped into the
transom bracket. If it is not snapped in correctly,
the speedometer will work inaccurately.
- If the installation is correct, but the speedometer
is still not accurate, the sender may not be
installed at the correct angle.
The old style sender is designed for a 12
transom. Installation on transoms that deviate
from that angle may require use of 1 or
2 wedges (Figure 2 above) in the sender
installation. The wedges can be used either thin
end up or down to achieve as close to a 12
transom position as possible.
The new style sender will accommodate
transom angles from 13 to 20 . Installations
outside that range will also require fabrication
and installation of shims to bring the angle into
- The gauge's part number can be found on its
Speedometer (Pitot Tube Type)
- The pitot tube speedometer operates by
air pressure changes in the hose and
speedometer. Water is pushed through the pitot
into the hose, compressing the air. Air pressure
increases with boat speed, causing the gauge
to indicate faster speeds. There must be air in
the hose. When the boat is still and the hose is
removed from the back of the speedo, no water
should pour from the hose. If water is in the
hose, blow it back to the pitot until air bubbles
exit. Reconnect the hose to the speedometer.
- Check hose for kinks or sharp bends that may
be cutting off air flow.
- Sometimes when a speedometer sits in the
environment for quite a while, as over the
winter, the internal metal parts form a coating
(verdigris). This may make it difficult for the
speedometer to op er ate. However, it should
recover with repeated use.
- If adjustable air pressure is available, standard
calibration speedometers should react to
the following pressures: 5 PSI = 20 MPH; 11
PSI = 30 MPH; 19 PSI = 40 MPH; and 30 PSI
= 50 MPH.
- A standard speedometer using the Mercury/
Mariner speed pickup in the engine foot will
read approximately 10% faster than with
a Teleflex pitot mounted to the transom.
Speedometers with the suffix "M" after the Part
Number are calibrated for use with in-foot pickups.
To test as in (4) above: 5.6 PSI = 20 MPH;
12.6 PSI = 30 MPH; 22.4 PSI = 40 MPH; and
35 PSI = 50 MPH.
- If the hose tends to blow off the hose barb
connection at higher speeds (to 80 MPH), clamp
a plastic wire tie over the hose on the barb.
- The pitot should be transom mounted at least 6"
from propeller tips.
- If the speedometer is not working, check that
the pitot has not kicked partially or all the way
up. This patented kickup feature is designed
to prevent transom damage from trailering or
submerged objects, and should not be disabled.
- The pitot is weed resistant, however, debris can
accumulate in its opening. Prolonged idleness
in the water may attract barnacles or algae. Be
sure the pitot allows water to enter the hose.
- When winterizing the boat, winterize the
speedometer system also. Remove the hose
from the speedometer head. Blow air into the
hose towards the pitot. Blow out any water that
may be trapped in the hose. Leave the hose
loose and the inside of the speedometer should
dry out over the winter (if there is any moisture
in side). Reconnect the hose before launching
the boat (or the hose will siphon water into the
- Accuracy between 5 and 35 MPH requires
the use of either a Teleflex pitot type 5-35
MPH speedometer or a Teleflex electric
(paddlewheel) type speedometer.