Holley pro-jection 2D - 20.1 Adjusting the Fuel Pressure; 20.2 Testing the Coolant Temperature Sensor

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- Kinked or restricted fuel line
- Faulty fuel pump
- Throttle body pressure regulator
improperly adjusted
- Low fuel level in tank
- Restrictive screen in tank
wiring harness. Check Battery voltage.
- Repair kinks and remove obstructions from
fuel line.
- See Item A
- See Adjusting Fuel Pressure section
- Add fuel to tank
- Clean fuel tank and increase screen size
L
High Fuel Pressure - Kinked or restricted fuel return line
- Return line diameter too small
- Throttle body pressure regulator
improperly adjusted
- Repair kinks and remove obstructions
from fuel line
- Replace fuel return line with larger
diameter fuel line.
- See Adjusting Fuel Pressure section
20.1 Adjusting the Fuel Pressure
The pressure regulator located at the rear of the throttle body is factory set at 15 PSI. A slight adjustment may be necessary to
allow for proper system operation.
1. Install a pressure gauge into the fuel supply line. This gauge must be removed after the fuel pressure has been properly
adjusted.
2. Start the engine and verify that the fuel lines do not leak. If any leaks are found, turn off the engine and repair the leaks
before continuing.
3. Insert a 5/32” Allen wrench into the pressure regulator screw on the top of the throttle body.
4. Turn the screw into the throttle body to increase the fuel supply pressure or out of the throttle body to decrease the fuel
supply pressure.
Figure 16
20.2 Testing the Coolant Temperature Sensor
The coolant temperature sensor used with the PRO-JECTION 2D system is a single wire sensor. The ECU supplies a fixed
voltage to the sensor. The resistance within the sensor varies with temperature and this variation in resistance is used by the
ECU to determine the engine’s coolant temperature.