Operation Manual

26
Diesel fuel flow sensor kit Installation and Operation Manual
NAVMAN
7-3-3 Locating the sensors in the
fuel lines
The supply sensor will be installed in the fuel
supply line between the the primary fuel filter
and the engine fuel intake. The return sensor
will be installed in the fuel return line between
the engine fuel return and the fuel tank. There
are several options where to locate each
sensor, discussed below, and the best option
will depend on the layout of your engine’s fuel
system and what fittings are used. Because
there is so much variation in fuel systems, this
can only be a guide to where the sensor should
be located. If in doubt, consult a qualified diesel
engineer.
Locating the supply sensor
Before planning where to install the sensor,
identify the supply line of the fuel system:
Find the primary filter - this will be in the
fuel line coming from the fuel tank, before
the lines reach the engine. To meet
modern recommendations these lines will
probably be of metal tubing, not flexible
hose. The primary filter is typically large
and has a clear sightglass and water and
sediment separation bowl. It should be
fixed firmly to the structure of the boat.
Find the outlet of the primary filter
- this should be labelled on the filter.
Sometimes there is a one-way or
non-return valve fitting on the outlet also.
Identify the fuel supply line from the
primary filter to the engine. A solid fuel
line usually has a flexible portion joining it
to the engine.
There are four options of locating the supply
sensor in the supply line:
1 On the outlet of the primary filter (see a
below).
2 In the solid fuel line between the primary
filter and the engine (see b below).
3 At the junction of the solid pipe and the
flexible hose leading to the engine (see c
below).
4 After the lift pump (see d below).
Locating the return sensor
Before planning where to install the sensor,
identify the return line of the fuel system. This
return line will most probably start from the
injector body on the engine, have a flexible
section to take account of engine movement,
then return to the tank in solid wall pipe.
There are three options of locating the return
sensor in the return line:
1 At the junction of the solid pipe and the
flexible hose leading from the engine (see
c below).
2 In the solid fuel line between the engine
and the tank (see b below).
3 On the return inlet of the fuel tank (see e
below).
Sensor mounting positions
This section discusses issues relating to the
different mounting positions for supply or
return sensors.
a On the outlet of the primary filter
(supply sensor only)
Install the sensor after any one-way or non-
return valve fitting on the outlet of the filter.
This might be the best option if the fuel line
is all flexible.
Note:
You have to recognise and obtain the
correct fitting to match the fitting on the
outlet of the filter.
The diesel flow sensor has a female
thread. Connection to a filter with a
female thread outlet, will require two
fittings, a male to free rotating female and
a male to male.
Ensure there is little strain on the sensor
or the filter. When using solid fittings, the
sensor mounting block must be made
accurately and the sensor positioned
accurately. If the installation requirements
allow, use a short length of flexible fuel
hose between the filter outlet and the
sensor.