Fuel Pump Question...STRANGE NOISE

[j.hardstyle]

I already know the general consensus will be "YES GO GET A FUEL PUMP NOW!!" but i want to know what you guys think of this...its strange.

For the past couple weeks, I have been hearing a strange noise coming from the fuel tank when my gas is below half tank....closer to the 1/4 tank and below mark though. At first I was parked and thought the noise was coming from outside, like someone was using an air gun of some sort but it was coming from my fuel tank!

It sounds like a puff of air, or actually a release of air....take for example if a big truck releases the pressure from its air brakes (like a semi). Except of course its not THAT loud, but i am sure its the fuel pump making this noise. I havent read anything on the forums about anyone encountering that noise, which is why i am curious about it.

My pump has starting to hum/whir a little. I can hear it more nowadays than when i first got the car, so I assume its just time to change the pump. But why could it be making that noise i explained above?

[OwnerCS]

Where are you located? Can you let us know the trunk temperature when this happens?

Do you know if the pump is the original?

My 91 still has the original pump but I keep a spare pump available in the event it should start making noises.

[j.hardstyle]

I am in Washington state. It has been cold here the past month or so...temps in the trunk are 50 or less...

This sound is noticable when the car is stopped or parked and just idling. I dont notice it when i am driving.

Also, i just pulled the pump 2 days ago to change the o-ring....i BELIEVE it is the original pump, but i have no idea. It was a JECS pump, everything looked pretty new though. The fuel tank was clean when i removed the pump, the only thing was the little strainer sock was a brownish color, rather than white....so I assume it is original. Everything looked shiny, no rust or corrosion.

The pump was making this noise BEFORE i pulled the fuel pump, by the way...and still makes the noise even after reinstallation.

[j.hardstyle]

Also, forgot to mention that my car just past the 140,000 mile mark.

[OwnerCS]

I think Qship96 found a good deal on a new Bosch pump through Amazon.com He likes it as far as I know

[j.hardstyle]

I remember reading that a couple days ago....on Napa's website, they list the Bosch fuel pump as the OEM pump. But I know for a fact that the JECS pump is the ORIGINAL kind from 92, made in Japan. They may have switched to Bosch in later years though.

Airtex is available from Autozone, and I know for a fact they make OEM parts such as IACV's and such....so I am wondering how good that is compared to the bosch, etc.

[qship96]

The Bosch pump is the JECS pump,same thing,different label, still made in japan too. JECS was a company co-created by Nissan and Bosch in 1973 to allow Nissan access to Bosch injection and engine control {computerized} parts {which they stamped as jecs,and allow bosch an inroad to japanese manufacturers.The bosch pump works perfectly,been in now for about 20,000 miles or so ........pumps are good for about 150K tops, replace it now before it strands you.


Airtex,carter,walblo.....why roll the dice when the oem bosch is attractively priced??????

[j.hardstyle]

Good to know....so since mine is labeled JECS, do you think it is the original pump? Or is the Bosch pump still labeled JECS as well?

[qship96]

considering you are just experiencing the noise now {and your signature says your car has 140,000 miles on it} it is probably the original {at 140,000 miles it is too early to have been replaced once and be failing already}. Bosch only labeled their parts as jecs when they were sold to nissan- they remained labeled as bosch when sold to distributors and their own retail networks outside nissan. Nissan/ bosch sold the entire jecs company to hitachi about 10 years ago.....who knows if they {the new jecs} ever even maintained production of the pump- never seen one marketed anywhere?

[j.hardstyle]

Yea i imagine it to be the original then....but have you ever heard of the pump making this type of noise? What could it possibly be doing to create that noise? The best comparison would be if you were removing an air hose from an air compressor...that short burst of air is the sound the pump is making...of course not as loud.

It doesnt make the sound constantly...it will do it, wait a few seconds then do it again, wait some more then do it again...only at idle when stopped or in park. I cant hear it while driving.

[Q451990]

Doesn't sound like anything I've heard of before...

Heath

[Lokim]

Sounds more like the evap system is being either overpressurized and is blowing off pressure or there is too much negative pressure and you're hearing the fuel cap release. Try a new fuel cap (cheap) and see if anything changes. If not, find the evap purge solenoid and disconnect the hose from the charcoal canister to the solenoid and see if that helps. Report back...

[j.hardstyle]

Can you tell me where the solenoid is located? Also, poking around under the hood, i dont think I ever saw the charcoal canister.

I will try and take a video of the noise from my phone, not sure how well it will pick up but we will see.

[Lokim]

The evap purge solenoid is just forward of the throttle body. The charcoal canister is under the air intake box.

[Lokim]

More info here:
http://www.nicoclub.com/FSM/Q45/

The 1994 manual should be virtually identical to your 92.

[j.hardstyle]

Alright...so you are saying just unplug the vacuum hose going from the solenoid to the canister? And if that doesnt work then what?

One thing i want to mention....i just replaced the o-ring for the fuel pump and all 6 bolts that hold the fuel pump down because 2 bolts were missing originally. When i looked in there the first time, i did notice that there was one hard line off to the right side all by itself that was not tightened down. The flare nut was off and the line was just sitting in the fitting that comes off of the fuel tank.

I am not sure what that line is, but i connected it like it was supposed to be because i was having issues with a fuel smell in my car. I thought it was because of that line not being connected and also the fuel pump not being bolted down properly (due to missing bolts and the oring).....but when I pulled the pump, gas leaked all in the trunk so it smells like gas in there now anyways.

But i am wondering if that line that was not hooked up has something to do with the noise?

[Lokim]

Quite possibly. Try my suggestions, and we'll go from there.

[rabsusa]

Alright...so you are saying just unplug the vacuum hose going from the solenoid to the canister? And if that doesnt work then what?

One thing i want to mention....i just replaced the o-ring for the fuel pump and all 6 bolts that hold the fuel pump down because 2 bolts were missing originally. When i looked in there the first time, i did notice that there was one hard line off to the right side all by itself that was not tightened down. The flare nut was off and the line was just sitting in the fitting that comes off of the fuel tank.

I am not sure what that line is, but i connected it like it was supposed to be because i was having issues with a fuel smell in my car. I thought it was because of that line not being connected and also the fuel pump not being bolted down properly (due to missing bolts and the oring).....but when I pulled the pump, gas leaked all in the trunk so it smells like gas in there now anyways.

But i am wondering if that line that was not hooked up has something to do with the noise?

- a tell tale sign that some ones already been in there..... do you get positive pressure blow out when you remove the gas cap for fueling? try prev posters comments, if no change replace, just because it is OEM does not mean its the orig, someone prolly replaced it already with a junk yard used unit. When i worked in repair biz, i replaced pumps at 4-5 yrs old with junk yard units; they were driven by "brothas" always on E or fumes and in FL they went out fast

[Infinitiguy19]

I thought that the fuel pump internals were cooled by the fuel it pump? Thats what Q ship said...

[j.hardstyle]

Yes, positive pressure is released when I take the cap off. I ordered a brand new Bosch fuel pump, so when that comes in there will be no questions about it.

Now I just have to figure out my fuel smell issue....no visible leaks but strong fuel smell when filled all the way up. I am checking the hardlines under the trunk today and if I cant figure it out, I am yanking the f*** fuel tank and replacing it. Its been an ongoing issue and its pissing me off.

[j.hardstyle]

I found a fuel probably causes poking around the trunk today....it helps that I have another Q now to compare to.

I found the red rubber line disconnected (that runs from the filler neck to under the trunk, in case of fuel spills)...I connected it. Also, I removed the fuel tank completely from my 94 and noticed that there are small o-rings on the hard lines, and they butt up against the fittings on the tank itself. I dont remember ever seeing these on my 92....and I have been seeing some bits of moisture/vapor being around the fittings, so I can only assume that is attributing to the fuel smell as well.

Regardless, when my new fuel pump comes in, I will be putting it into the fuel ta nk I just removed....removing the fuel tank thats currently in my car and swapping it out. Put all new o-rings where the fuel lines go into the fittings and then see what happens after everything is put back together.

The reason for swapping fuel tanks is because the one in my 94 is shiny and looks to be untouched...all the fuel pump bolts are there, the tank was still stuck to the floorboard with that sticky s***, the fuel pump harness still had the shrink wrap, etc. I know it has not been messed with. On the other hand, the tank in my 92 is white and corroded looking...I know it has been removed previously (possibly even swapped from a different car) because the sticky crap at the bottom of the tank is not original (its broken up), the fuel pump harness doesnt have the shrink wrap and there was originally 2 bolts missing to hold the pump down, AND not to mention the fuel overflow hose wasnt even connected!

[rabsusa]

I found a fuel probably causes poking around the trunk today....it helps that I have another Q now to compare to.

I found the red rubber line disconnected (that runs from the filler neck to under the trunk, in case of fuel spills)...I connected it. Also, I removed the fuel tank completely from my 94 and noticed that there are small o-rings on the hard lines, and they butt up against the fittings on the tank itself. I dont remember ever seeing these on my 92....and I have been seeing some bits of moisture/vapor being around the fittings, so I can only assume that is attributing to the fuel smell as well.

Regardless, when my new fuel pump comes in, I will be putting it into the fuel ta nk I just removed....removing the fuel tank thats currently in my car and swapping it out. Put all new o-rings where the fuel lines go into the fittings and then see what happens after everything is put back together.

The reason for swapping fuel tanks is because the one in my 94 is shiny and looks to be untouched...all the fuel pump bolts are there, the tank was still stuck to the floorboard with that sticky s***, the fuel pump harness still had the shrink wrap, etc. I know it has not been messed with. On the other hand, the tank in my 92 is white and corroded looking...I know it has been removed previously (possibly even swapped from a different car) because the sticky crap at the bottom of the tank is not original (its broken up), the fuel pump harness doesnt have the shrink wrap and there was originally 2 bolts missing to hold the pump down, AND not to mention the fuel overflow hose wasnt even connected!

good observations! one thing i ll note reg fuel pump - it is NOT an item that can assessed by miles on the car or apparent miles since last change. my bro has my 94 Q1, i had from new, never had anything in it other than 93 octane, (oil only synth btw) and has always been refueled at 1/4 tank mark, suffice to say he is on the very same FP. When runnng on constant E mark here in Fl ("poor owners") i seen them go out in as little as 2 yrs,

rob

[j.hardstyle]

Yea, I dont know what the previous owners did, so I am just swapping fuel tanks, installing a new fuel pump, putting new o-rings on the hardlines and putting it all back in. Problem should be eliminated....we will see!

[j.hardstyle]

I swapped fuel tanks yesterday....my new Bosch fuel pump came. Installed that, put everything together and the car wouldnt start...I never heard the fuel pump prime at all. Took the pump back out and everything was wired correctly, so I swapped out the FPCM and put the fuel pump back in. Turned the key "on" and heard the pump prime. Car fired right up.

NOW my question is this...I know everyone says the brand new Bosch pumps are "nearly silent"....mine isnt. I can hear it loud and clear. I still have my rear deck removed and all the fabric crap in the trunk is still out of the car....but this pump is far from "nearly silent". So did I get a faulty pump?? Or.....how silent is this thing supposed to be?

Also, the FPCM that I replaced was from a 94....does that matter?

[j.hardstyle]

I just checked the old FPCU that was in my car....saw the one pin burnt on the unit itself. The new one I put in has no burnt pins.

NOW, on the connector itself, that pin is a bit colored. The plastic isnt melted....but does this connector need to be changed or is it fine? My fuel pump runs and the car drives, havent noticed any funny business.....other than being able to hear the pump.

[qship96]

I would not mess around with the FPCU if it is operating correctly,although it never hurts to carry a spare in the trunk {I do,even though my original FPCU is currently powering its 3rd pump and appears to be working perfectly with 285K on it}

the noise you hear from the pump really cant be considered normal/abnormal due you hearing it without first replacing the rear deck{and rear seats I assume} and trunk liner- replace all that trim and see what you hear. FYI my current Bosch pump is silent, yet the Infiniti branded one{purchased brand new} I had before was not when it was installed...yet it lasted 150,000 miles- so even if your new pump is not dead silent,it still should last a long time.

[qship96]

I found a fuel probably causes poking around the trunk today....it helps that I have another Q now to compare to.

I found the red rubber line disconnected (that runs from the filler neck to under the trunk, in case of fuel spills)...I connected it. Also, I removed the fuel tank completely from my 94 and noticed that there are small o-rings on the hard lines, and they butt up against the fittings on the tank itself. I dont remember ever seeing these on my 92....and I have been seeing some bits of moisture/vapor being around the fittings, so I can only assume that is attributing to the fuel smell as well.

Regardless, when my new fuel pump comes in, I will be putting it into the fuel ta nk I just removed....removing the fuel tank thats currently in my car and swapping it out. Put all new o-rings where the fuel lines go into the fittings and then see what happens after everything is put back together.

The reason for swapping fuel tanks is because the one in my 94 is shiny and looks to be untouched...all the fuel pump bolts are there, the tank was still stuck to the floorboard with that sticky s***, the fuel pump harness still had the shrink wrap, etc. I know it has not been messed with. On the other hand, the tank in my 92 is white and corroded looking...I know it has been removed previously (possibly even swapped from a different car) because the sticky crap at the bottom of the tank is not original (its broken up), the fuel pump harness doesnt have the shrink wrap and there was originally 2 bolts missing to hold the pump down, AND not to mention the fuel overflow hose wasnt even connected!

good observations! one thing i ll note reg fuel pump - it is NOT an item that can assessed by miles on the car or apparent miles since last change. my bro has my 94 Q1, i had from new, never had anything in it other than 93 octane, (oil only synth btw) and has always been refueled at 1/4 tank mark, suffice to say he is on the very same FP. When runnng on constant E mark here in Fl ("poor owners") i seen them go out in as little as 2 yrs,

rob

Fuel pump has finite life based on amount of hours operated,just like any other electric motor that uses carbon brushes- brushes wear down to the point they no longer make electrical contact and pump stops operating- so, yes time/miles operated is a key indicator of remaining pump {motor} life-

[j.hardstyle]

Qship, I am uploading a video to Youtube now of the sounds....

On another note, the FPCU from my car had one burnt pin....and the corresponding pin on the harness side is a bit colored because the burn on the FPCU itself. I have a new (used) FPCU from my 94 in the car currently....it is running the fuel pump fine. But my question now lies in the harness....the wires are not melted, and the connector is fine, just a bit brown in that lower left pin. Is the harness still OK or does that wire need changed?

[j.hardstyle]

https://www.youtube.com/watch?v=Cj3jj8o ... ata_player


[youtube]Cj3jj8oxaaQ[/youtube]

[qship96]

Harness should be ok if the insulation on the wiring is not melted, the pins can be cleaned with a swab dipped in alcohol or electrical parts cleaner if you want to,but obviously they are passing the electrical current if the pump is running. I looked at your video, the pump can be heard, but again, put the trim back together and then see if it is loud......that is what counts! How full/empty is your fuel tank when that video was made, as that makes a big difference in the loudness also,especially when measuring right at the tank itself.