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Northstar Explorer 657 Installation and Operation Manual88
c A fuel transducer may be clogged. If so,
remove the transducer from the fuel line
and gently blow through it in the opposite
direction to the fuel flow.
A fuel filter between the fuel transducer and
the fuel tank must be installed as per the fuel
installation guide. Failure to do so will void
the warranty.
d Inspect the fuel cable from end to end for
damage such as cuts, breaks, trapped or
squashed sections.
e Check that the fuel filter is clean.
3-3 A twin engine installation shows only one
flow rate:
a Check that the number of engines is set to 2
(see section 17-5).
3-4 Erratic Fuel Flow readings:
a The fuel flow transducer may have been
mounted too close to the fuel pump or may
be subject to excessive vibration. Refer to the
installation instructions supplied with the fuel
transducer.
b Check for leaks in the fuel line or in the fuel
pickup in the tank.
c The Flow filter value is not suitable for
the engine. Check that the value is not set
to zero, then try increasing the value until a
steady flow rate is shown (see section 17-5).
3-5 There is no reading for fuel economy:
a The boat must be travelling through the
water to generate an Economy reading.
b Check that the paddlewheel on the
transducer is spinning freely and that the two
magnets in the paddlewheel are still in place.
B-4 Sonar fishfinding problems
4-1 The 657 operates erratically:
a Check that the transducer does not have
debris (e.g. weed, plastic bag) caught
around it.
b The transducer may have been damaged
during launching, running aground or
while underway with debris etc. If the
transducer has been impacted, it may have
been kicked up on the bracket. If it is not
physically damaged, reset the transducer
back to its original position. (See the Transom
Transducer Installation Guide.)
c When the transducer is less that 2 ft (0.6 m)
from the bottom, the depth readings may
become inconsistent and erratic.
d Manual Gain may be set too low, which may
cause weak bottom echo or no fish signals. If in
Manual Gain, try increasing the Gain.
e Ensure the back of the bottom surface of the
transducer is slightly lower than the front and
the front is as deep in the water as possible
in order to minimize the generation of
bubbles through cavitation. (See the Transom
Transducers Installation Guide)
f Check the transducer and power cable
connectors at the back of the display unit
are securely plugged in and the collars are
locked in place. The collars must be secure for
watertight connection.
g Inspect the power cable from end to end for
damage such as cuts, breaks, squashed or
trapped sections.
h Ensure there is not another fishfinder or
depth sounder turned on, which may
interfere with this 657.
i Electrical noise from the boat’s engine or
an accessory may be interfering with the
transducer(s) and/or the 657. This may cause
the 657 to automatically decrease the Gain
unless using Manual Gain.
The 657 thus eliminates weaker signals such
as fish or even the bottom from the display.
This may be checked by switching off other
instruments, accessories (e.g. bilge pump)
and the motor until the offending device
is located. To stop problems from electrical
noise, try:
- re-routing the power and transducer
cable(s) away from the boat’s other
electrical wiring.
- routing the display unit’s power cable
directly to the battery with an in-line fuse.