Fuel System Vacuum Pressure Standard; Fuel Hose Routing Resistance Measuring Method - Yamaha F70AET Rigging Manual

FUEL SYSTEM VACUUM PRESSURE STANDARD

In high-horsepower V6 models, the required fuel flow volume at normal operation may become
insufficient and the engine's reliability may decrease, due to the routing resistance of the fuel hoses
and the installation of a larger fuel filter. For the fuel hose routing standard, be sure to consult the
service network as well as the boat manufactures.

FUEL HOSE ROUTING RESISTANCE MEASURING METHOD

No. Description
(1) HOSE JOINT
(2) HOSE
(3) HOSE
(4) CLAMP
VACUUM PRES-
(5)
SURE GAUGE
1. Connect a 50 mm (2.0 in.) clear hose (market obtainable) (2) to the top nipple of the hose joint (1).
2. Connect the other end of the clear hose (2) to the engine fuel filter outlet.
3. Connect the fuel hose (3) to the center nipple of the hose joint, and the other end of the fuel hose
to a vacuum gauge (commercially obtainable) (5).
4. Connect the fuel pump hose to the hose joint, and then fasten all hose connections with clamps
(4).
5. Start the engine, let it warm up, and then measure the vacuum pressure at idle and wide-open
throttle, after the breaking-in period has been completed.
6. Measure and check that the vacuum pressure is within specification, and then route the fuel hos-
es to their original positions.
Part No.
6E5-24378-00
Commercially obtainable
61A-24313-00
90465-10098
Commercially obtainable
9-5
Hose to gauge
(1)
(3)
(5)
Q'ty
1
50 mm (2.0 in.) clear hose (inside diameter is 8
1
mm (0.3 in)) used to check for air bubbles
L = 300 mm (11.8 in.)
1
(250 to 400 mm (9.8 to 15.7 in.) is acceptable)
4
Specified pressure range: –101 kPa
1
(2)
Short clear hose
to fuel filter
(4)
Hose to fuel pump
Remark
(–760 mmHg) to 0