Automotive Troubleshooting Fuel System Inspection


Inspection method (gasoline engines)
Inspect the following when cranking the engine.
(1) Pinch the engine compartment fuel hose with your fi ngers and check whether or
not fuel pressure is applied.
(2) Check the sound that the injector is making.

• Fuel pressure is applied to the fuel hose, then tension increases and the hose pulsates. When there is no fuel pressure: A malfunction may exist in the fuel pump system
• Injector is making a sound When the injector is not making a sound: Exchange the connector with one from the next cylinder. If a sound can be heard, the injector can be judged as normal. The malfunction can be found between the ECU and the wire harness.

Inspection method (diesel engines)
When inspecting a diesel engine’s fuel system, separate the system into its compartment segments and check into which part the fuel comes.
(1) Is the fuel coming to the injection nozzle?
Loosen the union at the injection nozzle when cranking the engine to check the fuel injection condition.
Cover the injection nozzle with a cloth so that the fuel does not spatter.

When fuel spurts intermittently from the loosened part while cranking, it is normal.
(2) Is the fuel in the injection pump?
Check the sound of the fuel cut solenoid.

If a sound can be heard when the ignition switch is ON and OFF, it is normal.

(3) Is the fuel coming into the injection pump?
Disconnect the pipe at the injection pump inlet and check whether fuel is supplied when it is sent by priming pump pressure.
When fuel comes out of the inlet, the passage between the fuel tank and injection pump is normal.
• If there is no malfunction in (1) to (3) above, the malfunction is in the injection pump.
• For the common rail diesel engine, an inspection cannot be performed at the injection nozzle.

Related Post