Low fuel pressure can cause low power. Low fuel pressure can also cause cavitation of the fuel which can damage the fuel injectors. The following conditions can cause low fuel pressure:
- Plugged fuel filters
- Air in the fuel
- Debris in the check valve for the fuel priming pump or the pressure regulating valve
- Debris in the fuel tank, fuel lines, or fuel system components that create restrictions
- Leak on the inlet side of the fuel pump or the fuel lines
- Faulty fuel pressure regulating valve in the fuel transfer pump
- Faulty return fuel pressure regulating valve in the fuel filter base
- Worn fuel transfer pump
- Damaged fuel lines or fuel line fittings
- Fuel lines with deteriorating interior surfaces
- Undersized fuel lines or undersized fuel line fittings
Excessive fuel pressure can cause fuel filter gaskets to rupture. The following conditions can cause high fuel pressure:
- Plugged orifices in the fuel pressure regulating valve
- Stuck fuel pressure regulating valve in the fuel transfer pump
- Pinched fuel return line, fuel line, or fuel filter
The typical fuel pressure of the engine at operating temperature can vary. At low idle, the fuel pressure can be
The performance of the unit injector deteriorates when the fuel pressure drops below
| Required Tools | ||
| Part Number | Part Name | Quantity |
| 1U-5470 or 198-4240 |
Engine Pressure Group or Digital Pressure Indicator |
1 |
| |
| Illustration 1 | g00294866 |
|
1U-5470 Engine Pressure Group | |
| |
| Illustration 2 | g00911299 |
|
Typical location of the fuel pressure tap | |
To check the fuel transfer pump pressure, remove the plug from the fuel filter base. Install the 9T-6635 Connector with a 3K-0360 O-Ring Seal. Install a pressure gauge, and start the engine.
The 1U-5470 Engine Pressure Group can be used in order to check the fuel pressure of the engine. The engine pressure group includes Special Instruction, SEHS8907, "Using the 1U-5470 Engine Pressure Group". This instruction provides information about the usage of the group.