RESOLVED: 97 Q45 fuel pump makes humming noise

[chris2020p]

Hello everyone,
Can I replace the fuel pump on my 1997 Infiniti Q45 myself?
Where is it located?
Any write-up on this? (with pictures preferrably?)

Background story: I just don't feel like my Q45 has enough acceleration and sometimes I sometimes hear an audible humming noise coming from the rear while driving my Q45, it's not terribly loud at all but loud enough for me to turn my head and wonder what the heck that noise is. This is my first rear wheel drive vehicle so at first I thought it was the differential doing its job but now I'm pretty sure its the fuel pump.

When the hum happens I ONLY hear it when I touch the accelerator pedal, as soon as I let go it quiets down, so I can effectively play a tune by tapping the pedal.

Also, in the morning on a cold start, it takes longer to start up but after that throughout the day the start-up is INSTANT, here's my best explanation of it:

Morning on cold start: Tch-tch-tch-tch-tch-VROOOM!
After that during day: Tch-VROOOM!

* New valve cover gaskets
* New power steering pump
* New rack & pinion
* New NGK SPark Plugs
* New IAC Valve
* New Coils
* Flushed ALL fluids & replaced with AMSOIL ( Transmission, Engine, coolant, brake fluid, power steering fluid, etc.)
* New fuel filter

Thanks in advance for your help,
Chris

[speedeast]

The fuel pump is supposed to make a hum sound. It's when there is no hum that you should be worried. You may not have noticed, but you probably hear it a lot less on a full tank than if you were almost empty.

Acceleration problems can be a number of different things. A fuel pump is one of those things, but I don't think it is an issue in your case. Has the car had a decent tune-up in a while? I would go on changing the spark plugs, the air filter, the fuel filter, oil/oil filter, and run some injector cleaner.

[elwesso]

The fuel pump is supposed to make a hum sound. It's when there is no hum that you should be worried. You may not have noticed, but you probably hear it a lot less on a full tank than if you were almost empty.

Acceleration problems can be a number of different things. A fuel pump is one of those things, but I don't think it is an issue in your case. Has the car had a decent tune-up in a while? I would go on changing the spark plugs, the air filter, the fuel filter, oil/oil filter, and run some injector cleaner.

Not true.. Every Q45 fuel pump Ive dealt with have been whisper silent. If it sounds like a humming (like a small beehive) then its worn and time to replace... While not as common on this generation of Q, I would imagine they use similar pumps as the early Q.

Fuel pump problems are easiest to diagnose by checking fuel pressure... TEE in a fuel pressure gauge and make sure you're getting about 35PSI at idle, and 42 when your cranking (IE when you turn the key on but not starting the engine)

If its low, you should replace your pump.

Also, take your car to autozone or something like that and check your ECU codes, and report back.. They will do it for free.

[speedeast]

Well, with the way he described it, I assumed it to be a very subtle hum... and what's with the only at night part?

[Q451990]

Well, with the way he described it, I assumed it to be a very subtle hum... and what's with the only at night part?

Maybe his A/C is running quieter at night with less heat to deal with?

Heath

[Calizzaran]

I changed my 97 Q45 when I had one to a new fuel pump to only realize if you dont have all the plastics covering it and what not you actually hear it especially if its quiet. You can test by turning your car on and pop your trunk and listen to the fuel tank. Might be a bad Fuel Filter. Only weird thing is if its happening at night do you mean when your driving or when the car is turned on?

[chris2020p]

The fuel pump is supposed to make a hum sound. It's when there is no hum that you should be worried. You may not have noticed, but you probably hear it a lot less on a full tank than if you were almost empty.

Acceleration problems can be a number of different things. A fuel pump is one of those things, but I don't think it is an issue in your case. Has the car had a decent tune-up in a while? I would go on changing the spark plugs, the air filter, the fuel filter, oil/oil filter, and run some injector cleaner.

Yes, my car has had the most all inclusive tune-up that a normal person could think of & more: New valve cover gaskets, new power steering pump, new rack & pinion, new NGK spark plugs, new IAC Valve, new coils, flushed every single fluid possible to AMSOIL (Transmission, Engine, Coolant, brake fluid, power steering fluid, etc.) & maybe one or more things I can't remember.

Car runs almost perfectly except for I just feel like not enough power & the humming noise when it does happen it is not annoying but loud enough for my passenger to say " What's that humming? "

[chris2020p]

Not true.. Every Q45 fuel pump Ive dealt with have been whisper silent. If it sounds like a humming (like a small beehive) then its worn and time to replace... While not as common on this generation of Q, I would imagine they use similar pumps as the early Q.

Fuel pump problems are easiest to diagnose by checking fuel pressure... TEE in a fuel pressure gauge and make sure you're getting about 35PSI at idle, and 42 when your cranking (IE when you turn the key on but not starting the engine)

If its low, you should replace your pump.

Also, take your car to autozone or something like that and check your ECU codes, and report back.. They will do it for free.

I would like to try to do the fuel pressure test but I don't know how, what do you mean by "TEE"?, where do I get a fuel pressure gauge? Thanks.

Also, I have my own ODB II and the only code I ever got was a month ago "misfire on cylinder 4" that was coupled with an idle @ bump which I resolved by replacing ALL coils with brand new ones & ever since then never got a bump or any code whatsoever, not even a "PENDING" or "HIDDEN" code or anything.

[chris2020p]

Well, with the way he described it, I assumed it to be a very subtle hum... and what's with the only at night part?

I think the random louder than usual hum probably happens randomly at anytime of the day but most likely I only notice it at night because during the day there are always tons of cars whizzing by me making all kinds of noises effectively drowning out the fuel pump noise but @ night the roads are clear & my passenger & I hear it.

[chris2020p]

Well, with the way he described it, I assumed it to be a very subtle hum... and what's with the only at night part?

Maybe his A/C is running quieter at night with less heat to deal with?

Heath

My A/C is off @ these times.

[chris2020p]

I changed my 97 Q45 when I had one to a new fuel pump to only realize if you dont have all the plastics covering it and what not you actually hear it especially if its quiet. You can test by turning your car on and pop your trunk and listen to the fuel tank. Might be a bad Fuel Filter. Only weird thing is if its happening at night do you mean when your driving or when the car is turned on?

Replaced fuel filter already, when the car is on I can only hear it if I open the trunk and listen in @ which time I hear a quiet hum.

[chris2020p]

UPDATE:

When the hum happens I ONLY hear it when I touch the accelerator pedal, as soon as I let go it quiets down, so I can effectively play a tune by tapping the pedal.

Also, in the morning on a cold start, it takes longer to start up but after that throughout the day the start-up is INSTANT, here's my best explanation of it:

Morning on cold start: Tch-tch-tch-tch-tch-VROOOM!
After that during day: Tch-VROOOM!

[Calizzaran]

Well it sounds like you might have a faulty fuel pump. Whats the mileage on the Car?
There is also another odd thing to do with the alternator or power issue which causes a hum inside the car come from the speakers but its more of a wine noise if you can hear the hum come directly from the gas tank I suggest take the plastics in the trunk off and listen directly to the pump and if that is wining and your over 100K Miles suggest you might have a failing pump

[chris2020p]

Well it sounds like you might have a faulty fuel pump. Whats the mileage on the Car?
There is also another odd thing to do with the alternator or power issue which causes a hum inside the car come from the speakers but its more of a wine noise if you can hear the hum come directly from the gas tank I suggest take the plastics in the trunk off and listen directly to the pump and if that is wining and your over 100K Miles suggest you might have a failing pump

Hello,
The mileage on my 97 Q45 is 166K. Yup, definitely coming from the rear. On idle I can't hear the hum from my car but if I just open the trunk I can hear the quiet hum from there.

[chris2020p]

My local Technician replaced the fuel pump with some aftermarket bullcrap and it fixed the issue BUT the fuel pump was noisy, pitch/hiss too loud/annoying!

Had him replace it again under warranty and it was quiet at first then started making a different noise, this time a scratching noise!, fu*king annoying!

THEN, I got myself a BRAND NEW BOSCH! fuel pump and PERFECT!!!