What Are the Step-by-Step Instructions for Troubleshooting Fuel Injection Issues?


Quick Answer

One reason a fuel injector doesn't work is faulty fuel pressure; to check this, attach a gauge, and take several readings. Readings to take include static fuel pressure, residual fuel pressure and running fuel pressure.

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Full Answer

Check the static fuel pressure by turning the key on, but keeping the engine off. The fuel pressure should appear quickly and hold steady. Compare this reading with the vehicle's specifications. If there is no pressure, the voltage may be the issue. In this case, the solution is to install a new fuel pump. Low pressure is caused by either the fuel pump or the fuel pressure regulator.

To check the residual fuel pressure, look at the pressure after the pump stops running. If the pressure drops quickly, the vehicle may have a leaky fuel pump check valve, fuel line, fuel pressure regulator or injector. You may also notice vapor lock when it is hot outside or hard starting.

While the engine is idling, perform a running fuel pressure test. The fuel pressure should fall within the range set by the vehicle manufacturer. If it is too low, the problem might be low voltage, a week pump, a clog, a near-empty fuel tank or a bad pressure regulator.

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