Engine Compartment And Fuel System Pressure And Temperature Test; Connections - Mercury MerCruiser Product Applications Manual

6. The engine physical volumes are included in the table for use in computing the volume
of air in the engine compartment. This information is needed for determining the
ventilation requirements for venting fumes (refer to appropriate standards).
7. Ensure that water does not enter the ducts.
8. Air inlet ducts must be located in an area where they will not pick up exhaust fumes.
Engine Compartment and Fuel System Pressure and Temperature
Test
NOTE: Due to numerous similarities, the tests for the fuel system have been incorporated
into this test. All of these tests should be performed at the same time.
These tests require the use of a precise pressure gauge (manometer) and a thermocouple
temperature meter that can accurately read the ranges shown in the specifications table.
These items can be obtained by purchasing a boat audit tool kit.
Maximum engine compartment pressure differential @ WOT (inside vs. outside)
Maximum temperature @ fuel inlet
Maximum temperature @ top of engine compartment
Maximum fuel pressure drop @ fuel inlet
This test is very sensitive to the ambient temperature and the Reid vapor pressure (RVP)
of the fuel used during the test. Equipment is provided in the boat audit tool kit to measure
the RVP if this information cannot be obtained from your fuel distributor. This test should
be performed under the highest ambient air temperatures that the boat will be
subjected to in the markets where it is to be sold.
The engine compartment must be completely closed and in a condition for normal use.
Route the hose and leads from the test instruments into the engine compartment through
a vent or a screw hole. If routing through a hole, ensure that it is sealed.
This test needs to be performed with the boat in the water and underway. No special loading
characteristics are required, but the boat should be capable of reaching WOT. The boat
tachometer should not be used due to a high level of variation.

Connections

1. Test the engine with the longest length of fuel line or the most fuel components.
2. Connect a ¼ in. NPT female brass cross fitting between the fuel inlet and the boat's
fuel supply hose using appropriate hardware. Close the fuel shut off valve or clamp the
hose to prevent fuel spilling into the bilge.
Equipment needed:
¼ in. NPT female brass cross and appropriate fittings
Fuel inlet connection
Thermocouple
Fuel supply hose
Pressure gauge hose
3. Install the thermocouple into the brass cross with a ¼ in. NPT thermocouple fitting.
Connect the thermocouple to the meter using an extension cord.
4. Connect the pressure gauge to the brass cross with no more than 1.5 m (5 ft.) of hose.
A longer hose is convenient; however, it will give unstable readings.
90-863758060 AUGUST 2006
Description
Air Intake System
Specification
51 mm (2 in.) Water
44°C (110°F)
80°C (176°F )
6.9 kPa (1 psi)
Page 4A-3