Starting Fuel Increase Correction; Acceleration Fuel Increase Correction; Deceleration Fuel Decrease Correction; Correction Based On Intake Air Temperature - TOHATSU MFS25 Service Manual

Fuel System (Fuel Injection)

2) Starting Fuel Increase Correction

At engine starting (cranking), amount of first fuel injection of each cylinder is increased (by extending injection period) to
facilitate starting.
In addition to this basic correction, information including cooling water temperature, atmospheric pressure and intake air
temperature in the manifold from individual sensors are used to correct the engine operation to the best operating
conditions.

3) Acceleration Fuel Increase Correction

When pressure in the intake manifold is reduced below a certain setting value, ECU determines that engine is accelerated
and increases fuel injection amount.

4) Deceleration Fuel Decrease Correction

When pressure in the intake manifold is increased over a certain setting value, ECU determines that engine is decelerated
and decreases fuel injection amount.

5) Correction Based On Intake Air Temperature

ECU adjusts fuel injection amount for correction according to manifold intake air temperature that depends much on
outboard motor operating conditions and whether engine is cold or warm.

6) Correction Based On Cylinder Cooling Water Temperature

ECU adjusts fuel injection amount for correction according to cylinder cooling water temperature when engine is rotating
at low speed or high speed.
ECU increases the amount when engine is cold, and resumes standard basic amount as engine warms up.
(4) Control of Fuel Feed Pump (FFP)
During normal operation : ECU performs on/off control for fuel feed pump (FFP) by using output signal from its pump
At starting
When stopping
(5) Control of Tachometer
ECU performs on/off control for tachometer by using pulse input signal (On-off signal).
Pulse output rate is 6 pulses per crank revolution (12 poles).
When using accessory tachometer, set selector switch to 12 p (poles).
4-18
control circuit.
: Pump control circuit outputs signal to pump (FFP), and power is supplied to pump driving DC
motor to operate pump (FFP).
: Power supply to motor is shut off to stop pump (FFP).
25/30 2006