Gilera 633721 Workshop Manual page 226

Injection
7 - Check whether the pressure decreases with the
same trend as the system when free from bottle-
necks
AHEAD go to 8
8 - Pressure decreases much more slowly
YES go to 9 NO go to 10
9 - Replace the pressure regulator. Check the sys-
tem seal again.
10 - There occur trend variations
YES go to 11 NO go to 13
11 - Repeat the test clamping the pipe of the spe-
cial tool in the portion between the branch and the
injector.
Check whether the pressure decreases with the
same trend as the system when free. Pressure
decreases much more slowly
YES go to 12 NO go to 13
Specific tooling
020480Y Petrol pressure check set
12 - Check and replace the injector, if required,
due to an insufficient seal.
(see "THERMAL GROUP AND TIMING SYSTEM
")
13 - There are no trend variations
Repeat the test clamping the pipe of the special
tool in the portion between the branch and the
pump. Check whether pressure decreases much
more slowly.
YES go to 14 NO go to 15
Specific tooling
020480Y Petrol pressure check set
14 - The pump unidirectional valve is faulty. Replace the pump. (see Pump bracket overhaul)
15 - Check the pipe and the injector union seals more carefully.
Check the component seals again, if necessary.
A POOR SYSTEM SEAL ONLY AFFECTS THE START-UP VELOCITY.
INJEC - 226
Nexus 500 euro 3