Fault Phenomenon: Dynapac F1800C paver when spraying emulsified asphalt, the valve cannot close, spraying continues.

Troubleshooting Process:
– Checked spool: solenoid valve spool stuck in open position by debris.
– Checked spring: return spring broken.
– Checked electrical: control signal not de-energized.
– Checked fluid: emulsified asphalt dried.

Root Cause: The spray control solenoid valve spool is stuck in the open position by dried emulsified asphalt or debris, unable to return to close.

Required Parts: Clean or replace spray solenoid valve.