The only systematic way to diagnose problems with fuel pump wiring is to follow the process for potential faults in the electrical system. The primary source of this is the fuel pump relay since it energizes the pump. Automotive experts believe that an estimated 30% of fuel pump failures are due to electrical problems, such as relay failures.
Then measure the voltage at the fuel pump connector using a multimeter. The voltage should be between 12 and 14 volts at ideally. If readings are below this limit, they suggest a likely wiring problem -- as in broken wires or a bad connection. If you have such an issue a common symptom is a no-start due to the failed activation of the fuel pump, which applies in about 20% of vehicles that do have starting problems.
Now taking a look at -- and this is our small connector for our 6-pole setup here.Make sure that there are no visible damages on the wires; make sure they're not corroded or that there are any bare spots, shorts in them.And then go ahead and check to see if it is connected properly. Lab studies suggest that up to a quarter of all cases of wire failure in old vehicles are the result of environmental factors such as humidity and heat degrading wiring over time. “Even a little fray in the wire can interrupt power to the fuel pump and cause performance problems,” says mechanic Tom Harris.
If the wiring looks okay, ground connections. This makes it impossible for the fuel pump to operate properly. Also your ground wire should show almost the same mojo in voltage; if it is entirely off there may be a grounding issue. This is a step most car owners tend to forget but actually, 15% of the failures are due to grounding issues.
Diagnostic Another method is by hearing the fuel pump running when turning your key into the on position. A good pump should emit a quiet humming sound for approx 5 sec. Should other be the case and you don't hear anything, then better take a closer look.
To sum up, diagnosing fuel pump wiring problems involves testing the fuel pump relay, checking voltage at the connector, examining the wiring harness and verifying ground connections. Find out more about keeping your fuel system running the way it should there are several Fuel Pump resources available on the web. Fixing these electrical issues can greatly improve the reliability and driveability of your vehicle.