PURPOSE: To reduce the quantity of fuel injected in case of automatic variable speed, and to remove the blow-up of an engine in case of the release of a clutch by setting up a solenoid valve into a fuel-feed path between a feed pump and a plunger barrel and intermittently opening and closing the valve.

CONSTITUTION: A pressure chamber 16 is partitioned by a plunger 32 in the plunger barrel 30. A suction port 15 for the chamber 16 is communicated with the fuel-feed path 35, and the solenoid valve 41 is fitted into the feed path. Fuel supplied to the plunger barrel from the feed pump is reduced by intermittently opening and closing the solenoid valve 41. Accordingly, the blow-up of the engine is removed when the clutch is released because of automatic variable speed. Constitution is made simpler than that of devices in which rack levers are controlled.