92Q..When Do I Look For the Fuel Pump "Hum" if it's Bad?? HelP!!

[Dustkicker]

After also running out of gas, I have been reading lots of posts (weeks) about my resluting problem. After running out of gas, my Q has not been able to accellerate and lacks responsive power above 40 mph.

At idle, and up to about 35 mph, I can rev up to 4500 rpm or more. But once I reach 40 mph, it won't exceed 3400 rpm! If I am going, say 60 mph, and punch the gas, it just sputters and creeps along. Same if I am going 70...takes forever to reach 80 mph. I can't risk trying to pass at any speed unless there is lots of time/room.

BTW, so many of the posts complains of stalling out at stops, slowing, idling climbing hills, etc. My Q NEVER stalls. So, my case seemed different.

I had dismissed a Fuel Pump problem because I had never heard a hum noise. I don't understand anything, yet, about checking /ohming injectors;There is no Infiniti dealer in Savannah to do a fuel rail flush. So, I was saving those for last when I will take a drive to a dealer in Jacksonville or South Carolina.

I have cleaned the MAF and connector, TB and butterfly (all twice). and I ran 1 can of BG44k with 3/4 tank of Cheveron 93 Octane. These did not fix the problem.

Now, I have appt at a local shop tomorrow to have them check the injectors, but it occurred to me that I mght have been listening for the wrong thing (Hum) on the Fuel Pmp.

Does this FP Hum you guys referenced occur AT IDLE? At NORMAL driving? At ACCELLERATION? ALL the time or INTERMITTANTLY?

It occurred to me today that when I punch the gas and try to accellerate, I do hear a different sound ( I called it engine straining) that could be the HUM you guys are talking about. Otherwise, it runs quiet.

Please let me hear back what are your thoughts. Any comments are appreciated.

92 basic Q, 181000 miles, Plugs and under plenum hoses and chain guides, done. Prior owner did sched maintenance + fuel pump, but I don't know at what mileage pump was changed. I have had it since 137,000.

Thanks, Frank

[Rex]

Do you know the last time the fuel filter was changed? There's a good chance when you let eh car run out of gas, so "debris" got picked up and (hopefully) stopped at the filter. Get one, and a can of BG44K from Joe and see if that resovles it. It's a cheap "try" and probably needs doing anyway.

[redmanfx]

At idle, and up to about 35 mph, I can rev up to 4500 rpm or more. But once I reach 40 mph, it won't exceed 3400 rpm! If I am going, say 60 mph, and punch the gas, it just sputters and creeps along. Same if I am going 70...takes forever to reach 80 mph. I can't risk trying to pass at any speed unless there is lots of time/room.

I have cleaned the MAF and connector, TB and butterfly (all twice). and I ran 1 can of BG44k with 3/4 tank of Cheveron 93 Octane. These did not fix the problem.

Frank

Almost sounds like a knock sensor problem, not a fuel issue...O2 sensor??.. I would have the codes checked for sure, because I'm betting you are throwing some codes for sure. Find a shop that has OBD I consult for Asian cars and get it checked. If you cleaned the MAF good and the connectors are good then I'm thinking Knock sensors for some reason. Just a feeling.

[Dustkicker]

Thanks, Rex for the quick response. In fact, I forgot to say I DID change the fuel filter last weekend - and added the BG44k right afterward. I am getting an order from Joe on Firday and 2 cans of BG44k are in my order (I also have a 95Q that I am trying to service).

Is 4 days running with the BG44K and new fuel filter enough time to expect the see results? Thx, Frank

[Dustkicker]

Thank you, I wouldn't have known to ask the shop if they have OBD I. Will it check/find either KS or/and O2 sensors? Is KS an under plenum job?

[redmanfx]

It's a consult that they plug into a port on the drivers side lower left hand side of dash. The car will "throw" codes for any problems it has. When reading these codes the shop will know what's wrong specifically with the car. The Knock sensors and O2 sensors are under the plenum area. I'm not saying that is your problem, but I had the same sluggish thing going on at one point and then an RPM problem as well that turned out to be bad knock sensors. Most shops charge anywhere from $50 to $75 to hook up the consult to check codes so make sure they can read a 92 Q. Some shops may be nice and not charge you much, say $20.

[Q451990]

Keep in mind that the ECU on OBD1 cars are sort of dumb. There may or may not be codes. Is your idle irregular? A dead miss from a bad injector will typically show up as a "bouncing" feeling... I think I could actually see the front of the car bouncing when mine were bad. The lack of acceleration makes me think it may be a fuel pressure or MAF problem. With one dead injector mine would still drive fine... just vibrations, but faster than most things on the road. Your RPM caps almost make me think the car is in "limp mode" but the RPM limits seem off...

I assume when you mention a dealership in SC, your referring to Key Infiniti in Hilton Head? That's a very new dealership, so I would specifically ask if they have any techs. that were around in the early 90s when they saw more older Qs. My wife used to work at Gulfstream, so I'm pretty familiar with the drive down there! Nothing more boring that 26 south of Columbia to Pooler GA!

If you're ever up in the Columbia area let me know and I'll let you know what I think...

Good luck!

Heath

[Q451990]

Might be worth picking up a fuel pressure gauge at Harbor Freight.... I bought one but haven't tested it yet.

http://www.harborfreight.com/c...D=138

zerothread?id=170698

Heath

[Dustkicker]

Understood. Well, if consult will find the problem, it will be worth it of find out what is reallyh wrong with this chariot!

I'm still curious to know about when a fuel pump "Hum" is heard when a fuel pump is bad. At what point do you heard it...or is it all the time? Can anyone whose had a bad fuel pump shed some light?

Thanks

[Q451990]

The hum is most obvious at idle... you typically won't hear it during acceleration. The noise is worst when the gas tank is below 1/2. Did your problem start as soon as you put gas back in the car after running out?

Heath

[Q451990]

I just noticed that you had a similar problem with your 95 Q back in 2004... do you think this issue seems a lot like that one? At least you have fuel pump replacement experience!

Heath

[Dustkicker]

Thanks, Heath..I almost moved to Columbia instead of Savannah...long story.

It is Key Infiniti. Did not know they were new (I'm new here myself), but one reason I haven't run over there already is that they were going to charge me $185 just to "check out" my A/C to see why is was not cooling two weeks ago on the same car. Not to fix anything.

No, my idle-ing is smooth and quiet. About 850 rpm steady. When driving down the road, the tach sits around 2000 withour bouncing around, too. It's only when I accellerate that the needle goes up to 3400, pauses as I hold down the pedal, and slowly falls back w/o reaching over 3500.

Once in a while, it will snap me back in the seat between 25 and 40 MPH and the tach will jump up to 4500 -just to tease me! I then try to repeat this euphorea again above 40MPH and it just snickers at me like an old lady and strains to keep from slowing down!!

You can tell I'm frustrated to laugh at it so I don't cry.

[Dustkicker]

Yes, I noticed a big difference in driveability as soon as I put gas into the car after running out. But, it has gotten worst because the first week I could still accellerate great above 65 miles mph , once I reached cruising speed.

In fact I took a 114 mile drive (to a funeral) in 1 hr 20 min --and got 21 mph on the tank. The next tank got 11 miles per gallon while I worked on finding the problem.

[Dustkicker]

My 3rd attempt to answer you..system keeps crashing!!

Only similarity with the 95Q fuel pmp problem is that this 92Q also will not rev up about about 3400 rpm! But the 95 would stall and shut down (and not restart for about an hour or so) everytime i got in to bumper to bumper rush hour traffic and dropped down to less than 5 mph.

THis one NEVER stalls or refuse to start.

I deffinitely will not let the dealer/shop put in the FP if that ends up being the problem. Thanks to NICO, I can do it myself. Yea!

Thanks, Frank

[goody90q45]

In fact I took a 114 mile drive and got 21 mph on the tank. The next tank got 11 miles per gallon while I worked on finding the problem.

Don't pay to have a dealer check the simple stuff. That's why you belong to NICO- so you can do the simple troubleshooting yourself. You can ohm the injectors and knock sensors and check the codes from the ECU all in less than an hour. The only tools you need are a VOM, a 10mm socket and ratchet and a phillips head screwdriver. Checking these three things will tell you a lot. Go to Q45.org for easy to follow instructions.

I was thinking fuel pump problem until you said your mileage had dropped to 11mpg. I think you need to pull the plugs and check for fouling. You may have a couple of leaky injector o-rings. Also check to see if any of the plugs are wet with fuel. Pulling plugs is not hard either but does take a few more hand tools. Good luck.

Correction- Sorry, I thought this was a 94. I don't know if the 92 has the flashing light on the ECU.

[Dustkicker]

Hi Mike, thanks for the encouragement. I have those 3 tools and I certainly want to learn how to work on my own. (But my wife won't let me get under a jacked-up car to work, so I got stuck with a two different $600 bills to replace alternators in the past two months).

I am going to go over to Q45.org to follow up on your tip as soon as I get up in the morning. I feel so dump when it comes to omns, ejectors, knock sensors and the like. It will be nice to understand some of that.

BTW, that 11 miles per gallon may be a distraction. The NEXT tank has 147 miles on it and the needle has not yet reached 1/2 tank. So, your first thoughs might still be on target.

Anyway, I will do these checks in the morning and report back on the leads you and the other fellows gave me.

Thanks, Frank

[Dustkicker]

Just want to say thanks for all your advice and help. I just added a FUEL PUMP to my order with Joe for the 92 Q. It was the fp all alone just as NICO threads suggested.

No ECU codes; #8 ejector dirty; BUT FUEL PRESSURE was ONLY 20 PSI, insted of 43+ PSI.

But, chalk my 92Q up as another bad FP that had no hum and no engine stall out at low/idle speed.

Thanks to you, I had my first experience with ohming ejectors and with trying to dig into ECU/Consult. Still don't have a handle on the latter - but I will with some more reading/effort.

Anyway, my Q should be back up to par again next week. I will also be replacing it's cracked Fan blade. NEXT: what to do about that "Darlington Resistor" and Black Fan Blower motor.

Thanks, Frank

[Q451990]

How did you determine the injector health and fuel pressure? Did you visit Key Infiniti or a local shop? If it was diagnosed with a Consult - did they give you a print-out of the power balance test?

After you complete your fuel pump replacement, I would highly suggest a pressurized rail flush!

Heath

[Dustkicker]

Heath, I ran the ohm tests with an ohm meter myselfl using the procedure Goody94Q45 pointed out to me.

When I went to my ECU/Consult, I couldn't fugure out how to read it (didnt see/have the screw slot to insert a small screwdriver). Key Infiniti could not get me in until next wed, So, I went to a local shop to have them check it. They tested the FP pressure..but didn't give a power balance printout.

QUESTION: Would it be better to have Key do the pressure fuel rail flush BEFORE I put the new FP in, or wait until after it is in?

Thanks, Frank

[maxnix]

QUESTION: Would it be better to have Key do the pressure fuel rail flush BEFORE I put the new FP in, or wait until after it is in?

Thanks, Frank

Probably after, but the return is blocked anyway.

Be sure they use the BG machine for the fuel rail flush.

If not, http://www.bgfindashop.com

[Q451990]

I just wonder how they diagnosed a specific injector clog without a power balance test...

Heath

[Dustkicker]

I just put in my zipcode at BG site and found 4 dealers (Not Infiniti) and 2 shops near me. So, I won't be going to Key Infiniti for the flush unless I still need the PB test.Thanks,

[redmanfx]

I haven't been to a single place yet that does a flush correctly, so just be careful when they say they are done and ask them exactly what they did. Most only run cleaning agents and dont check anything or remove a thing! Biggest rip off there is. After one such flush the #1 injector was so clogged, I know they didn't check it or they would have seen the black chunks in the tip.... How do you do a flush and not check to see if you flushed build up right into the injectors????

Sorry, fuel rail flushes are a sore subject to me since I've gone through a few to clean my system and all were a big joke!!!

[Dustkicker]

Thanks for the heads up on the rail flush deficiency to expect. I will get some explanation up front of what will be done and hope for honest follow thru. I appreciate all the NICO feed back I've had because it is pretty much a given that every thing is new for me and potential for repair rip off is ever present.

BTW, NICO save me $$$ again because the shop said the FP job would be $858; which included $615 for the pump!! Thanks to NICO, I knew better - plus I know it's a DIY job. And, Joe charged me $229 for the pump, plus about $4 for the O ring.

Frank

[Dustkicker]

Most only run cleaning agents and dont check anything or remove a thing! Biggest rip off there is.

Redmanfx, what should be removed when a rail flush is done? Thanx

[Q451990]

A proper injector flush includes pulling both the fuel supply and return lines from the fuel rails - they are looped together so that the fuel pump just feeds fuel back to the tank... then the return outlet from the fuel rails is capped. Then the pressurized canister is fed to the fuel input tube on the fuel rail. Start the car, and it runs on the injector cleaner...

If the return line isn't looped back - much of the injector cleaner bypasses the injectors and ends up in the fuel tank!

Now the fun part! The final step is driving the car "like you stole it" for a while. Several WOT (wide open throttle) to redline starts... high RPM runs on the interstate (hold in 3rd at 80 MPH for a while) to make sure any deposits that were flushed from the injectors don't bake themselves on to the pistons and valves.

Heath

[Dustkicker]

Boy, I'm glad I asked! I think I will go to the infiniti dealer for the flush service. I would expect them to do it right even though I will pay more. I would not know if a shop (or dealer) did it right.

Thanks again. If I make it up to Columbia one day, I'd like to catch up with you.

[Q451990]

Don't count on quality service from a dealer either... Mine can't replace a battery correctly on the G! Left acid under there and can't put the plastic cowl/cover on right... car has been at the dealership since Friday!

Maybe Key will be better...

Heath

[litlchi]

Not sure where Savannah is, but if you're close to Atlanta, you should probably call to see if T3 does it. Seems like a many people on this forum love that place. Just my 2 cents.

[Q451990]

Savannah is a few hours from Atlanta... not bad, but probably not worth it just for a rail flush. Now... if you wanted to make the journey for several things at once I would absolutely recommend it. Maybe a transmission flush, rail flush, some other maintenence...

Heath