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Dan, Technician
Category: Nissan
Satisfied Customers: 23484
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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Symptoms Of A Bad Fuel Pump Or Fuel Pump Relay.

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What are the symptoms on a bad fuel pump or a bad fuel pump relay?

If you have a bad fuel pump the vehicle may stall or not start and usually does not show a check engine light. If the fuel pump relay has failed, you will not hear the pump hum when you turn the key into the on position or hear the relay click. The only way to be certain is connect a fuel pressure tester and make sure vehicle has proper fuel pressure.

Let me know if you have any other questions.


Customer: replied 7 years ago.

Lately, it doesnt start more than it does. It may not start for 7 days but on that 8th day, it will start up and possibly on the 9th day as well.

Does this sound like it is the fuel pump/relay or something else?

Is your check engine light on? If not, a fuel pump would be a likely problem. The only way to be sure is to do a fuel pressure test.

What year, model, make and engine size is your vehicle?

I''ll look up specifications and see if there is any common problems.


Customer: replied 7 years ago.
Well, my service engine light is on. The car is actually an infiniti I30, 1998. 6 cyl engine, 3.0 ltr

The most likely problem is a failed camshaft sensor or mass airflow sensor. Test during no start condition. You can backprobe the wires at the camshaft sensor and check for AC voltage while cranking. If no voltage replace.

Here are troubleshooting steps along with location pictures. If you wanted to make it easy on yourself, drive the car to a parts store next time it runs, have them hook it up on a scan tool and give you the trouble code. That will give a more exact direction in where to locate the problem.

1. At the Mass Air Flow (MAF) sensor, verify that the connection is good and the Black/White wire has battery voltage and the Black wire has a good ground.

2. Check the signal wire or the White wire, the voltage should be approximately 1.3 to 1.4 volts at idle. Always verify that the White wire is not intermittently grounding out. If the signal voltage goes high or low in relation to the airflow and the harness and connection are good, then suspect a faulty MAF sensor.

troubleshooting a failed camshaft sensor or mass airflow sensor

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