VESPA GTS Super 125 i.e. Service Station Manual page 126

Injection
Precautions
1 A MIU failure is more likely to be due to the connections than to the components.
Before troubleshooting the MIU system, carry out the following checks:
A: Electrical power supply
a. Battery voltage
b.Burnt fuse
c.Remote control switches
d.Connectors
B: Chassis ground
C: Fuel system
a. Faulty fuel pump
b.Dirty fuel filter
D: Ignition system
a. Faulty spark plug
b.Faulty coil
c.Faulty screened cap
E: Intake circuit
a. Air filter dirty
b.Dirty by-pass circuit
c.Faulty stepper motor
F: Other
a. Wrong distribution timing
b.Incorrect idle speed carburetion
c.Incorrect reset of the throttle valve position sensor
2 MIU system faults may be caused by loose connectors. Make sure that all connections have been
correctly made.
Check the connectors taking into consideration the following point:
A check that the terminals are not bent.
B check that the connectors have been properly connected.
C - Check whether the malfunction can be fixed by shaking the connector slightly.
3 Check the entire system before replacing the MIUIf the fault is fixed by replacing the MIU, install the
original control unit again and check if the fault occurs again.
4 Use a multimeter with an internal resistance of more than 10K Ohm /V when troubleshooting. Instru-
ments that are not suitable might damage the MIU central control unit. Use instruments with definitions
over 0.1V and 0.5 W , the precision must be greater than 2%.
INJEC - 126
Troubleshooting tips
Vespa GTS Super 125 i.e.