Fuel Pump Relays

Fuel Pump Relay Symptoms, Location & Replacement Cost

In Engine by 18 Comments

The fuel pump relay is an important component of the fuel system of your vehicle.

The fuel pump relay gives the fuel pump power when it is time to build up fuel pressure in the rail.

Whenever you turn on the ignition of your vehicle, the fuel pump relay is turned on.

There are different reasons due to which the fuel pump relay fails. In this article, we will discuss symptoms that your fuel relay failed, location, replacement cost, and how to diagnose it.

5 Bad Fuel Pump Relay Symptoms

The relay can fail due to many reasons, from dust to electrical power surges, anything can affect the well-being of a fuel pump relay.

The most common symptoms of a faulty fuel pump relay are check engine light on, rough acceleration, engine stalling, and the engine die when driving.

Here is a more detailed list of the most common symptoms of a bad fuel relay.

1. Check Engine Light on

Check Engine Light

The engine control module does always monitor all engine sensors to ensure they do not show the wrong values. If the ECU suspect a wrong value from any sensor, it will light up the check engine light.

The ECU monitors the fuel pressure with the help of the fuel pressure sensor. If the fuel pump relay suddenly fails, it will light up the check engine light and store a trouble code on the fuel pressure.

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2. Rough Acceleration

Slow Acceleration

The fuel pump relay going bad can affect the fuel pump’s power and affect fuel delivery to the engine. An engine runs on fuel just like the heart of a human runs on oxygen and blood.

Therefore, any fuel pump relay issues will affect fuel flow to the combustion chamber, and your vehicle might have problems starting.

However, this can happen due to several other reasons, such as a choked fuel filter, so you should always properly diagnose your car before replacing any parts.

3. Engine Stalling

Engine Stall

If the fuel pump relay may have any bad solderings inside it, it might suddenly lose the relay connection and stop delivering power to the fuel pump.

The engine turns off if the combustion chamber’s fuel is inadequate or doesn’t have the proper pressure.

The part that ensures none of this happens is the fuel pump, and it cannot work perfectly if the fuel pump relay develops any issues.

4. Engine is completely dead

Dead Car After Road

A faulty fuel pump relay can also cause the engine not to start at all and be completely dead. No fuel pressure means that your engine will never start, and if the fuel pump relay failed, it would not give any power to the fuel pump to build up fuel pressure.

5. No noise from fuel pump on ignition

Starting Car

When you turn the ignition on in the ignition lock, you should hear a whirring noise from the rear of the car. This means that the fuel pump started building fuel pressure in the fuel rail.

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If you cant hear this, there might be a problem with the fuel pump relay. You can try to listen closer around the fuel tank for any noise for 2-3 seconds after turning the ignition on.

Where is the Fuel Pump Relay Located?

Relay Fuse Box

In most car models, the fuel pump relay is located in a fuse box somewhere under your dashboard, but it can also be located in the fuse box in the engine bay.

The engine’s or the dashboard fuse box is usually a long black box containing a fuel pump relay and various other fuses and relays. For different vehicles, the fuel pump relays can be located in different places.

Check your repair manual for getting the exact location of the fuel pump relay fast.

Fuel Pump Relay Replacement Cost

The average replacement cost of the fuel pump relay is around $90 and $150. The parts may cost you between $20 and $50, while the remaining cost is the labor cost.

The fuel pump relay is a small electronic device easily acquired online or at the nearest spare parts shop. The fuel pump relay’s replacement cost involves the cost for the parts and the labor cost that the mechanic would charge you.

When considering the labor cost, it could be at least an hour of work or more in certain cases.

Depending on your mechanic’s hourly pay rate or the per hour cost, the repair shop would charge you; the labor cost may differ. Apart from the labor cost, the fuel pump relay is not a very expensive device, and you can buy one for $20 to $50 on average for most vehicles.

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Fuel Pump Relay Diagnosis

Bad Soldering Relay

Diagnosing a relay is often pretty straight forward. The fuel pump relay does often have 4 pins, and in this case, it is often easy. If your relay has more pins and not the same numbers mentioned here, you need to check a wiring diagram.

  1. Locate the fuse box and locate the fuel pump relay
  2. Lift it and check under it for the numbers 30, 85, 86, and 87. If you locate these numbers, you can put the fuel pump relay back.
  3. Put the relay back so you can reach the pins with a multimeter while you cycle the ignition.
  4. Turn on the ignition and check pin 87 with a multimeter. If you get voltage there, it may tell you that the fuel pump relay is working, but it can also have intermittent problems.
  5. If you do not get voltage there, make sure that you have constant voltage on Pin 30 with the ignition on. If you don’t, there might be a problem with a broken fuse. You should also have constant voltage on pin 85, and pin 86 should be grounded from the engine control unit when you turn on the ignition.
  6. If you found any problems with the relay, you can remove the case from it to check for any bad solderings. Resolder the relay if you find any problems.

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18 thoughts on “ Fuel Pump Relay Symptoms, Location & Replacement Cost ”

Comments
  1. I have a 2008 Pontiac Grand Prix and when I turn the engine off the fuel pump keeps running , and the fuel pump will come on without the key being in the ignition and keep running.

    1. Author

      In this case, you have to check the fuel pump relay to see if it’s constantly engaged. Check if the engine control unit are sending constant ground or 12v to the relay also.

    2. The mechanic installed new fuel pump on my 2005 Chevy Malibu engine cranks but won’t start.
      What could cause this? Also if it’s not the fuel pump will i still be charged for new one?
      I’m 74 and live alone just don’t know what to do.
      Help.

  2. My MB 560SL 1988 runs normal untill the engine is warm, then it starts shaking, power is going down and finally the engine stops. Immediate ignition and engine turns again. I can drive for half a mile and it starts all over and over again. Can the fuel pump relay cause this because a contact may not be Thx for your opinion.

  3. 09 cobalt. Had a friend hook computer to it and it said fuel pump relay.. ok great. Went and got another relay. And it still won’t crank up. Any suggestions please???

    1. Maybe u should check ur fuel pump,but I understand u webt with that test,u could also check ur ohms,and voltage their also,see if ur having issues with that

    2. Hi, my 2007 Chevy LS trailblazer stalls out while I’m driving. If I switch around fuel relay with another relay it starts up.I have put in the shop for 1 week the code is reading a bad relay. Could it be my fuel pump or should I just replace the relay??

  4. I have an Mitsubishi intercooler v6 engine ..
    I have an problem .when I start the enigne the engine switch off it self after few minutes..

  5. I have a 1996 Toyota Camry station wagon.
    There is a fuel pump noise that continues on and off when the car has been turned off and keys removed.
    The Camry runs well, but the sound is annoying at.
    Please advise what the problem may be and the best way to fix it.
    Thanks

  6. hi I have a 99 Chevy suburban. it stalled, I had the fuel filter replaced, fuel pump very loud when key turned no start. What do you think?

  7. I came into a 1992 Chevy Astro 4.3 all wheel drive not too long ago it runs really good then all the sudden now it’s wanting to stall out and not wanting to start and then when it does start it stalls back out sometimes it’ll run for a day and run good and then some days are just stall out and not start the filters good the pumps good the relay is good what else is there I was thinking maybe a crank sensor?

  8. 1995 f150 runs great 1/4mile then bucks like wild horse replaced new filter (3) times still bucks gonna drop tank replace pump or replace relay?

  9. Good evening, I have a Toyota avensis t25 and I have the following problem, after an hour it loses the gas pressure and when I turn the key on the switch in place
      acc the petrol pump does not press, making it difficult to ignite.

  10. Pump on Pajero nm 2000 doesn’t seem to have much pressure even when I hook 12 volts straight to it , relay not working that’s why I hooked 12 straight to it could you give me any idea , no fuel coming back in the return line

  11. Magnus – you have 22 steps in order to change out the relay. Do you really need to go thru that process? Couldnt you just remove the old one and install the new one while the engine is off?

    I believe my relay is going bad on my 97 chevy 2500. I bought a new one for $5 from rock auto and will be switching it out myself since it’s easily accessible in my fuse box.

  12. When i drive few Kms with my Opel Astra 160iE the engine stalls and few seconds when start it ,it start normally then after few kms again t repeat the very same thing . I bought a new petrol pump and filter still repeat the same thing.
    What could be the problem.

    Thanks

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