int r = 0;

void setup() {
pinMode(9, OUTPUT);
attachInterrupt(digitalPinToInterrupt(3), suma, RISING);
Serial.begin(9600);
}

void loop() {
switch(r){
case 0:
 apagado();
 break;
case 1:
bomba();
 break;
default:
r=0;
break;
}

}
void suma(){
r++;
}
void apagado(){
digitalWrite(9,LOW);
}

void bomba(){
digitalWrite(9, HIGH);

}