# Fuel pump, injectors?



## seafruit (Sep 5, 2005)

I have heard this "airlike" noise coming from underneath the back of the car by the tank. I thought it was odd. I now am experiencing a very defined engine miss. Have replaced distributor cap and plugs( NGK) again since Dec. Has brand new vol. reg., and rotor, plug wires since Dec. too. Is the sound I have been hearing the fuel pump going out? Is it in the gas tank? I am not burning any oil and there is a distinct carbon smell coming from the back sometimes mixed with a gas smell? The engine has been a great engine. It has 185,000 miles with no real oil usage. Any ideas. At about 2 rpm's just a little tap on the accelator caused it to shake. I thought I got rid of it b4 with some really great tranny additive. Somehow I think this is a fuel issue? It has had the tranny gone over and a recent torque converter replaced in 2003.

a maxima novice,
thanks in advance
Chris


----------



## gate9797 (May 27, 2006)

I used a boottle of STP injector cleaner with jet fuel to unclog an injector that would have cost 4 hundred to replace. This procedure seems to work and I use the stuff a couple of times a year as part of preventative maintenance.


----------



## DonaldHays (Jul 22, 2004)

Check the rubber hose that vents the fuel tank, It might have started a small leak, if it has it wont be to the amount you will notice, just the smell. My Maxima last summer went thru this (was on bad when the car was full and while driving aggressive in turns and such) worth a look and its most likely time for it to have started getting weak and maybe leaking a bit.

I know that the older 85-88 Maxima had leaky FI; I had two of those cars myself (was a safety recall on then) however on the 89-94s there is no recall. I have seen a lot about them leaking but thankfully mines still doing well so far (94 Gxe with 91,000 miles)

I have noticed recently that I have been getting a strange odor from my car after it sits for awhile (smells like a refinery would) like a nasty oil gas burning thing, don’t use anymore oil or gas than it ever has and once the car warms up it leaves (guess I will need to look into that one soon) Even after it sitting from 01-2005 it never made the yuck smell it does now until it warms up.

If it’s the fuel pump (not a big deal) its under the rear seat (10 minute job) maybe longer but seem to be like 10 minutes or so even if its longer, especially when places tell you 400-500 to replace it! 

Check all those awful vacuum lines under the hood also (they tend to be weak on any kind of car that is made after it gets so old!)

My Maxima has a new fuel pump in August of 2005 (we didn’t check the fuse first) oh well less to worry about later. My car does make a small air sound but only when its lower on fuel, they tend to get louder as they get weaker, so it might be trying to give it up sometime soon, if you have a weak weak one and drive the car with lower fuel and drive aggressive on the ramps onto the highway with lots of turn and curve to them the car will chock out and stall until it levels out and can start sucking fuel again (leaned that with my old Bonneville SSEI that we used to have) 

If you do a search, I think it tell you how to test for bad FI using a meter someplace here on the board. 

The Nissan as a whole is a pretty tuff little car, well most Nissans for that matter. Like I said I have a 94 Gxe with 91k and the Factory muffler on its just now starting to wear a bit weak on the stainless case (that’s awesome I think!) My 99 Sentra Gxe Limited has already had a new muffler with under 140k at that the time of replacement, but the sentra wasn’t ever as high grade as a Maxima unless you compare new Sentra against a older Maxima but that’s like saying to a salesman, I want the NSX for the price of a TL. 


Let us now what you discover on it all

Donnie H.


----------



## alexnds (Oct 1, 2005)

If bad injectors, a bottle of fuel injector cleaner might only mask the problem for a while, and you might to replace injectors. IF car starts to really shake, one cylinder is misfiring due to lack of fuel in that cylinder. Read some of previous posts on this topic. In my case, I bought used injectors, had them cleaned from witchunterperformance.com and then replaced all 6 of the all at once, because labor charge is the same to replace one or all 6 and fuel flow amongst them all will be more even.

Brand new injectors are very expensive, and you typically don't replace just the bad one, but at least all of them on the same side of the "V" in the engine, or all 6 as a whole. 

Let us know how it turns out.


----------



## gate9797 (May 27, 2006)

*Injectors*



alexnds said:


> If bad injectors, a bottle of fuel injector cleaner might only mask the problem for a while, and you might to replace injectors. IF car starts to really shake, one cylinder is misfiring due to lack of fuel in that cylinder. Read some of previous posts on this topic. In my case, I bought used injectors, had them cleaned from witchunterperformance.com and then replaced all 6 of the all at once, because labor charge is the same to replace one or all 6 and fuel flow amongst them all will be more even.
> 
> Brand new injectors are very expensive, and you typically don't replace just the bad one, but at least all of them on the same side of the "V" in the engine, or all 6 as a whole.
> 
> Let us know how it turns out.



I have had no problem with injectors since one injector was replaced, I also use the injector cleaner once in a while. The shop I use replaced one injector on one side for a reasonable price but when an injector on the other side started acting up they said that because of the position of the injector much more labor would be involved in getting it out. That is when I started using the injector cleaner. (93 maxima 255000 mi)


----------



## alexnds (Oct 1, 2005)

The stuff they sell in a bottle to put into your gas tank mostly cleans the intake valves and is not a "serious" heavy duty cleaner. In terms of the labor of replacing "one itn a difficult spot" this sounds like bunk. The work is the SAME, not matter what cylinder you're talking about. Not one cylinder is harder than any of the other cylinders.

Basically, the top of the intake manifold is removed, and a clean rag is stuffed into each cylinder to prevent from stuff falling in. Then, the electrical connectors per injector are disconnected and finally, each injector is pulled out. The new injectors are then put in their respective place and the procedure is reversed. Then, a fresh gasket is used to reseal the upper intake manifold to the engine. I don't know what shop you are going to, but the procedure I described has nothing to do with the level of difficulty of one bank of the V, over the other bank, or "one injector is more complex to remove in that particular spot than another". Sounds like they are giving you some phony story.

The reality is, that if your engine is 250k miles, the pulse width and so forth, of each injector has went through many , many cycles. It probably needs new pintle cap. Try to get all 6 replaced at the same time, because you'll be paying for the same procedure over and over, and over again as you start replacing one at time. Try this site for parts:

http://internetautomart.com/maxima/3rdgen.html

He's very reasonable and is a member. Good guy I recommend.


----------



## gate9797 (May 27, 2006)

*That is what I suspected*

What you are saying applies to a 93 Maxima SE? One of the reasons I posted about the injectors is that I suspected the shop was trying to rook me off and expected someone on the forum to have relevant information. Thanks for this information. I am not trying to preserve the vehicle forever. It seems to be perhaps time to let Old Betsy go next time a major expense arises, since I am not a mechanic myself and have to pay for pretty much all repairs.

That same shop replaced my clutch cylinders a little while ago. How can I test the old cylinders to determine whether they are defective?


----------



## alexnds (Oct 1, 2005)

*how to check which injector is bad?*



gate9797 said:


> What you are saying applies to a 93 Maxima SE? One of the reasons I posted about the injectors is that I suspected the shop was trying to rook me off and expected someone on the forum to have relevant information. Thanks for this information. I am not trying to preserve the vehicle forever. It seems to be perhaps time to let Old Betsy go next time a major expense arises, since I am not a mechanic myself and have to pay for pretty much all repairs.
> 
> That same shop replaced my clutch cylinders a little while ago. How can I test the old cylinders to determine whether they are defective?


I don't know about clutch cylinders and perhaps Matt can answer that one. However, the idea of check which injector is bad is pretty straight forward. You can do it two ways. Firstly, if the injector is bad, the resistance is higher, so if all the coils in the injectors are 15 ohms, the bad one will be like 22 ohms or something. The other way of doing it is similar to process of trial and error and I'll try to describe it here.

Let's say for instance, you didn't have spark in one cylinder. You would start the engine, and pull the spark wire from one cylinder at time. The engine would shake and die and misfire, because you'd be running on 5 out of 6 at thhat moment. However, if you keep pulling the ignition wire, one at time, per cylinder and replacing and restarting motor each and everytime, and when the motor RUNS THE SAME, like you didn't pull the wire, that is the cylinder that was missing spark in the first place! The same idea applies to injectors. If you pull the electrical connection to each injector, on at time, and your engine starts to shake, since it is running on 5 out of 6 at that moment, you know that cylinder was getting fuel. So, you re-attach the connector, restart the motor, and do it again, and again, and so forth. Finally, the one cylinder where the behaviour didn't change when the electrical connector to the injector was pulled away, THAT is your bad injector on that cylinder.


I hope I explained it. Do what I did. Get the color code or "dot" on your injectors. That is your first step. Perhaps they can tell you. Buy injectors and have them sent to be cleaned.

Read these sites for background info:

http://www.witchhunter.com/witchhunterequip1.htm

http://injectorcleaning.com/html/injector_cleaning.html

http://www.fuelinjectorsoutlet.com/...rs&OVKEY=nissan fuel injectors&OVMTC=advanced


----------



## alexnds (Oct 1, 2005)

Here is procedure for injector replacement so you can see what is involved. 

http://www.4dsc.com/articles/drivetrain/fuel_injector_replacement/fuel_injector_replacement.shtml


----------



## sweet3rdgen (Jun 9, 2006)

I definitely back Alexnds up on this one. there is no injector more difficult than another on the Maxima v6. There are all pretty easy to get to following the procedure Alexnds stated. Back in the day of big v8's in intermediate to small cars some spark plugs were difficult to get to. In early 90's Camaros and Firebirds the back plugs and injectors were damn near impossible to reach, but on a Maxima? Not remotely. I don't know the shop you went to. I don't know their reputation, but to me it sounds crooked.


----------



## internetautomart (Mar 8, 2004)

on a VE maxima the frot injectors can be done in 45 minutes, the back takes about 2 hours.
the difference is the front injectors are completely exposed versus the rears which are under the plenum.


----------

