Symptoms

• There are several symptoms an automobile can display that will help you determine if your fuel injector is working properly, such as power loss to the vehicle. A car that hesitates when you attempt to take off from a dead stop is also a classic sign of fuel injector problems.
  
  

Testing

• Another way to check and see if your fuel injectors are working properly is by running a flow test on them. The standard rate at which fuel should flow from the injectors can be compared with the injector's current flow rate. A flow that is not up to par indicates that your injectors have problems that need addressing.
  
  

Mileage

• Yet another way to find clues about the condition of your injectors is by figuring out the mileage that has been traveled with them. Because experts suggest that fuel injectors should be cleaned before reaching 30,000 miles, distances over this benchmark indicate a need to at least have your fuel injectors checked.