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Fuel Pump Relay Replacement Cost

Know what price you should pay to get your vehicle fixed.

The average cost for a fuel pump relay replacement is between $44 and $74. Labor costs are estimated between $26 and $56 while parts are priced at $18. Estimate does not include taxes and fees.
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What is a Fuel Pump Relay?

Relays are a very well known component, even when their purpose is unknown. They are often changed when something goes wrong, even when they have no relation to the issue at hand. Put simply, the complete job of a relay is to allow a high power circuit to be actuated by a low current switch. For example, a relay could allow a light switch to connect a power station to a city. The need for relays exists because the systems on a vehicle that run high amperage, like the starter, are switched by low amperage switches, like the ignition switch. Relays can have multiple circuits inside them, but to be plain and simple we will consider a one-way relay, the fuel pump relay.

How does a Fuel Pump Relay work?

The fuel pump relay powers the fuel pump, which takes considerably higher amperage than can be safely passed through the ignition switch, but must be powered when the ignition switch is in the 'run' position. A relay is the perfect tool for the job, and has remained reliable for decades. When the ignition switch is turned on, electrical power is sent from the ignition switch to the relay. Inside the relay there is a large circuit and a small circuit. The small circuit is for the power from the ignition switch, and causes the large circuit to close(connect) through electromagnetism. When the large circuit closes, power can now flow from the battery, through the closed circuit in the relay, and all the way to the rear of the vehicle to power the fuel pump.TO turn off the fuel pump, the ignition switch turns off, which stops electric power to the small circuit, so the electromagnet in the relay no longer closes the circuit. That means that when the electromagnet in the relay looses power from the ignition switch, the large circuit will open (disconnect). When the large circuit opens, the fuel pump loses power and stops running.

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What are the symptoms of a bad Fuel Pump Relay?

Intermittent fuel pump relay failure would cause the fuel pump to work sometimes, and it may stop running randomly while driving. Often, the complaint is that the key has to be turning in the ignition several times before the fuel pump begins to prime. Since the relay is the only thing that powers the fuel pump, when it shuts off while driving, the engine will turn off. Also, the relay can fail altogether, and the result is simply a vehicle that will not start unless starting fluid is used, or the relay is 'jumped'. Sometimes a borderline failed relay will click rapidly and audibly as the magnetic field created by the small circuit from the ignition is almost enough to close the larger circuit from the battery. This may, however, only indicate an issue with the ignition switch or the constant.

Can I drive with a bad Fuel Pump Relay?

A fuel pump relay should be changed right away. The vehicle will not be able to operate with a bad fuel pump relay, and leaving the relay jumped will cause the battery to drain and the fuel pump to overheat and fail. At some point, an intermittent or failing relay will completely fail, and the vehicle will leave the occupants stranded.

How often do Fuel Pump Relays need replacement?

Relays fail all the time, in new and old vehicles of all makes and models. Relays are generally reliable, but most vehicles will have at least one relay failure through the course of its service life. No matter how well made and how well maintained a vehicle is, the slightest bit of corrosion and years of wear on contact surfaces will eventually break down a relay. Also, if the relays are quickly powered on and off, such as with a dying battery, the contacts can arch and erode quickly.

How are Fuel Pump Relay issues diagnosed?

Diagnosing a relay is simple with testing. On the exterior of most relays there is a diagram of the switches inside the relay. In the case of the fuel pump relay, there will be a maximum of two switches, but normally only one. Applying power and ground to the small circuit with proper polarity should make the relay click. This, however, is only the first half of the test. The secondary test is to measure the resistance across the relay, and compare that to the data on the relay or from the service manual. If the resistance is too high across a realy, the powered component will not receive the high amperage current it needs, and therefore, the relay must be replaced. If the relay does not click, the same applies, but the second part of the test will yield infinite resistance.

How are Fuel Pump Relays replaced?

Replacing a relay is only a matter of identifying the relay according to diagrams in the owner's manual, under the lid of the power distribution or fuse block, or in the service manual for the vehicle. Once testing of the relay is complete, the failed relay is thrown away only after ensuring the new relay is exactly identical in function and size, and the new relay is firmly pressed in, pulled out, and once again pressed into the power distribution or fuse block. This will ensure that complete contact is made between the relay and the terminals on the vehicle.

RepairPal Recommendations for Fuel Pump Relay issues

Never attempt to repair a relay. There is generally nothing serviceable in a relay, and erroneous reconstruction will only lead to humidity entering the relay, a relay that does not function properly, or even melting of the entire relay. Relays are inexpensive sealed units that should be replaced, not tampered with.

What to look out for when dealing with Fuel Pump Relay issues

If a relay is proven good, but still does not function, the terminals can be tested in the junction block with a test light or multimeter. A multimeter is prefered because of the accuracy of readings, but a test light will inform the technician if power is present or not. Also, the ignition switch may provide a switched ground to the fuel pump relay, or it may provide a switched hot (battery voltage). This should be known when testing the relay and the power distribution block. In the case of a switched ground, there will only be continuity between the battery negative cable and the relay when the key is turned to the 'run' position, or when the fuel pump normally primes.

Can I replace the Fuel Pump Relay myself?

Relay testing and replacement is simple, straightforward, and could be a fun project to share with a family member. The issues start to emerge when the relay is diagnosed as operable, but is not activated when the ignition switch is turned on. If testing of electrical circuits is understood, and a multimeter with long leads is present, this repair can be accomplished at home, but if the circuit is not understood and the relay is good, leave the job to a professional. This will likely prevent further damage or electric shock.

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