Fuel Pump whine

[Jeff Williams]

I have heard a lot about fuel pump humming, or whine, or buzz.

My antenna makes a lot of noise going up, and down, when I turn on or off the key.

Sunday, I did not have the radio on, and was turning on the key, and hurd a humming noise, for about 5 to 10 seconds, then it quit. I first thought it was the antenna, but verified it was still down.

I turned the key off, them back on, and the noise was there, again. It doesn't buzz continuously, like I thought it would.

Is this my fuel pump?

I ordered one from Joe, on Tuesday, just in case.

182,000 miles, and I am not sure if the pump is the original, or not.

Any experience with this noise?

Am I just paranoid, from reading related posts?

Thanks!:help

[Rex]

Jeff - That sounds like the "priming cycle". If you start the car and then open the trunk (while it's in park ) and can hear a buzzing/whinning, then it's time to start planning the pump R&R.

[Jeff Williams]

Jeff - That sounds like the "priming cycle". If you start the car and then open the trunk (while it's in park ) and can hear a buzzing/whinning, then it's time to start planning the pump R&R.

So, the hum I heard, that stopped, might not be a bad thing!

I bought the pump, anyway, and it will be here tomorrow, but I might wait to install it, if mine is still O.K.

[DAEDALUS]

If it's humming, and especially if it's getting louder, don't wait too long.

[Q451990]

When the pump is really bad you'll hear a low huuuummmm from the back of the car at ilde all the time. I think the priming noise is somewhat normal, although there's been some debate on it. Mine with 5K miles on it has the noise when it primes.

Heath

[DAEDALUS]

The controller sends a small voltage (~2V) to the pump for about 5 seconds after the key goes to on, or until the car is started, whichever comes first. No reason for the pump to sound any different then than when the car is idling.

[elwesso]

Maybe its pumping air out of the pump, IE slightly cavitating.....

Mine does this too..... And tis a brand new pump... Some days worse than others but its not that bad at all.....

[Jeff Williams]

Maybe its pumping air out of the pump, IE slightly cavitating.....

Mine does this too..... And tis a brand new pump... Some days worse than others but its not that bad at all.....

I guess I'll hold it in stock, until I need it. Although, I didn't need to spend the extra $200+ right now.

[DAEDALUS]

Just remember that a pump can be bad and still "work". Better to spend $200+ sooner than $500+ later when the pump burns out the pump controller.

[Jeff Williams]

Just remember that a pump can be bad and still "work". Better to spend $200+ sooner than $500+ later when the pump burns out the pump controller.

DAEDALUS = Confucious

I think you are right. I drive mostly between 5:00 AM - 7:00 AM, and 7:00 PM - 10:00 PM. A tow truck is not what I want to be worrying about, at this time of the night.

By the way, can you send me your instructions on the Tokiko Blue strut swap? [email protected]

Thanks!

[Q45tech]

The FPC doesn't send any voltage to the pump. The FPC is just the electronic equivalent of a large 3 position resistor in the pump's ground circuit...........cxontrolled from the ecu.

Kind of like the HVAC fan speed controller except only 3 speeds.

Cold Start and WOT [the FPC acts almost like a short to ground], cruise [middle speed, and idle [slowest speed].

The pump's speed generates an audible tone when the wear causes the speed to decrease and come into the audible range.

Which can be a problem for young vs old folks [like me] as our hear frequency range diminishes with age and exposure.

[Jeff Williams]

So, since it was cold, I heard it do a 5 second burst of pressure to the system, on high flow.

I have not heard it since, and can n ot hear it while the car is at idle, whether the tank is full or near empty (I typically do not go below 3 gallons).

SInce the car is making so much noise at WOT, I would not normally hear it (Mostly because of the K & N POP Charger).

Dennis, is there a resistance I can check, to see if the pump is out of spec?

[DAEDALUS]

1 ohm IIRC, but what's really a good measure is the amount of current flow.

http://www.nissaninfiniticlub....40019

EDIT:

.5 ohms is nominal.

When the car is cold, the pump primes for 5 seconds at the lowest flow...hence 2 volts. I assume Dennis' reference to Cold Start is when the starter is cranked.

[louiegz]

Let me put out a stupid question out there. From what I read of the FP & the FPC on this forum, the worry about the bad fuel pump melting the sodder on the FPC is that too many amp will melt it. If you were to change the 15 amp fuse to a 10 amp fuse, would that act as a safety? Will the 10 amp fuse blow out too much to make this practical? A fuse is much cheaper that a FPC. I don't know. Would that work?

[maxnix]

The FPC doesn't send any voltage to the pump. The FPC is just the electronic equivalent of a large 3 position resistor in the pump's ground circuit...........cxontrolled from the ecu.

Kind of like the HVAC fan speed controller except only 3 speeds.

Cold Start and WOT [the FPC acts almost like a short to ground], cruise [middle speed, and idle [slowest speed].

The pump's speed generates an audible tone when the wear causes the speed to decrease and come into the audible range.

Which can be a problem for young vs old folks [like me] as our hear frequency range diminishes with age and exposure.

I am old and not quite deaf, but I never hear the pump on either of my G50 Q45s. Haven't used a stethoscope yet, so maybe there is hope.

[DAEDALUS]

Let me put out a stupid question out there. From what I read of the FP & the FPC on this forum, the worry about the bad fuel pump melting the sodder on the FPC is that too many amp will melt it. If you were to change the 15 amp fuse to a 10 amp fuse, would that act as a safety? Will the 10 amp fuse blow out too much to make this practical? A fuse is much cheaper that a FPC. I don't know. Would that work?

Interesting thought. Not a stupid question at all. This ties into the data Dennis is collecting on pump currents. I'd be afraid that occassional spikes would burn out the fuse. It would be an issue at WOT...like when you're passing. Wouldn't want the fuel pump to go out then! If you drive with respect to the risks, and with a spare 15A fuse just in case, it could be tested. Would be nice to have some kind of early warning. But what if the solder melts at 8A, or 9A?

[HeavyDuty]

EDIT: .5 ohms is nominal.

Jeff,

Mine started making an intermittent ooooooooo tone (e-minor) and by happenstance when I thought it pooped out, was only because I had a loose connection on my CPS helped along by me when I kissed the connector with my hand during an oil change.

There is a point here, hang on.

Fuel pump 1.1 ohms, way out of spec but still ran, although had a few long cranks every now & then.

So I changed the pump & the car cranked right up. (It went into limp mode during a shakedown run, that's how I found out about the CPS connector.)

When I examined the FPC, it was totally perfect.

Point is/was, because of a stupid oil change error, I probably saved myself the cost of a FPC. The pump was bad, but not bad enough to screw up the FPC.....yet.

Every now & then God gives ya one to keep you interested. :icesangel

[desertq45]

My experience with the fuel pump:

Occasional long cranking off and on for 2-3 months. Not very frequent, but enough to get my attention.

Just after replacing the transmission, I notices a buzzing noise-- kind of like "white noise" heard through an older car stereo when volume is low-- interestingly enough, my 64 year old father pointed it out one day while riding in the back seat (for those who think age the only cause of diminished hearing rather than say... frequent trips to the track :-)) so I knew from reading the many posts found here that the pump was suspect.

I checked with a friend/mechanic who also drives a Q and had he thought the buzzing was probably the module, not the pump-- although the pump would have been the reason the module went bad. So I picked one up used along with a new pump.

For many reasons, I continued to drive the car for a couple of weeks, still hearing the intermittent, yet more common buzzing, before having the chance to replace the pump. I figured since the module may already be toast, and I had a replacement, the only harm that could come would be "roadside assistance" during one of my short commutes.

Although the pump still functioned, when I pulled it out it and checked it with the meter it read 1.3 ohms. Significantly out of spec from what HeavyDuty states. I must have gotten lucky because when I replaced the pump I tried the old module and the noise was gone. I then put the other module in and there was no difference. So I assume I didn't run the bad pump long enough to damage the module, but now I don't know which part actually "made the noise". My assumption is that it was the module, but caused by the pump... but I don't know that for sure.

Either way, the job was about 1-2 hours and my original pump went 137k before all of this, so changing it was an easy decision. Now I don't have to worry about it for another 100k or so.

Plus, I also noticed a significant difference in consistent acceleration after replacing it. With the old pump I'd sometimes get a lag which I blamed upon the tired transmission. Then I rebuilt the transmission, but acceleration was still sluggish at times... then a new pump and now it runs like new.

[Jeff Williams]

Thanks for all the info.

This site rocks!