How to Remove Fuel Injector on 93 GXE - Nissan Forums : Nissan Forum
 
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#1 Old 08-13-2009, 03:31 PM
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How to Remove Fuel Injector on 93 GXE

Hi Everyone,

I read the FAQs on the Fuel Injectors as posted by 'jserrano' and a few other posts before posting my own question.

I suspect my injector #3 is not working - the only thing I haven't done yet is the multimeter reading for resistance since I need to get a new 9V battery.

Here's what I have checked and eliminated:

1) replaced spark plugs (they were old anyway)
2) checked and cleaned up the rotor and cap - working fine
3) verified it is not the ignition wires all are getting sparks
4) unplugged each injector with engine running and #3 made no diff on idle

5) I still need to swap the injector terminal with another one to see if it is possibly something related to the wiring (hope not!!)


I was going to take out the injector to see if there was some obvious blockage - but my problem is that the injector is damn tight, I could barely rotate it - is there a trick to removing it from the fuel rail without having to remove the rail itself? Or are they supposed to be that tight?

I wonder if it is because I haven't cut out the fuel pressure by removing the fuse for the fuel pump and then trying to start the engine?


Any suggestions? A new injector is $200 CDN and I am hoping it isn't dead..I was thinking of getting one from a scrapyard - but given the age of the car, I think I may run into that issue again - what do you all recommend?
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#2 Old 08-13-2009, 03:54 PM
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I have a fuel injector FAQ?? Where? You definitely need to depressurize the fuel rail first. Make sure the new injectors has good bottom o-rings. Some injectors are sold without o-rings!!! Without o-rings you'll flood the engine and cause a potential hydro-lock. And you know what hydro-lock can does, right? Bend your piston rods. I'm not trying to scare you just making you aware of this.

There is a simple way to tell whether the ECU is operating the injectors. Take a good spare injector and externally hook it up directly to the injector harness. With the engine running you can put your ear as close to that spare injector and listen (and feel) for clicking noise. You might need use a long handle to listen for the clicking sound.

One of my prefer ways to ruling out the injectors is to just detach the fuel rails, with the injectors attached, and crank the engine. You'll know immediately if a fuel injector is clogged, leaking, or has problems.



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#3 Old 08-13-2009, 05:18 PM
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Hi jserrano,

Yeah you had a posting about it and how to troubleshoot the injectors, I believe it was in the FAQ section for the first gen forums.

I forgot to add that I did try the long stick/screwdriver trick as well - but I didn't notice any difference in the sound between any of the injectors - I heard the "clicking" on all of them.

But since I have never had to listen for that sound I cannot be sure that what I heard was the right sound - maybe I heard the valves clicking? If it is an obvious clicking sound - then yes it was there. So maybe the injector is clogged?

And about your last comment, yes you are correct in that one would/should see fuel spraying from the injector - but can the rail be removed without first removing the injectors? I guess there's a set of gaskets/o-rings between the rail itself and the areas that it bolts on to?

Would releasing the pressure first necessarily make it easier to take out the injectors? I read one comment about using a flat blade screwdriver to pry them out - but looking at the injector itself it doesn't look strong enough - like it would crack or break if I tried that - and this is based on the fact that I tried "twisting" the injector back and forth to try and get it out and it took all my strength of my thumb and fingers to get it to rotate maybe 20 degrees.

From what others have written they make it sounds like the injector should just slide out easily without any unnecessary force or struggle.

Thanks again!
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#4 Old 08-13-2009, 07:35 PM
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Yes, you can removed the fuel rail with the injectors attached. Just make sure the injectors have their lockdown caps screwed in place.

I've also never been able to remove injectors easily as well. But use the technique described here and you'll keep yourself from going bald. (And yes, you can do this with the fuel rail still attached to the engine.)

http://www.nissanclub.com/forums/for...ml#post3602382



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HUD & ATC retrofitted, DEPO lamps, NGK Ignition wires.
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#5 Old 08-14-2009, 02:35 PM
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Ok, so I tried to run the Ohm meter test, but my meter kept reading "1" - so I am thinking that I don't have a low enough setting to read the very low resistance on the injector. The lowest resistance on my digital multimeter is 200 Ohms, which I thought should STILL get me a reading - unless I did it wrong.


I put the leads on the 2 terminal leads that are on the injector itself and not on the socket that comes off the injector. I tried all the other terminals and got the same reading. I tested another device and I did get readings so I don't think its my meter.

I couldn't swap the injector connector from another one that was working because it was too short and I didn't want to stretch the wire and cause unnecessary damage.


Here's a thought - is it worth saving some $$ by buying the entire fuel rail off of another car (I know of one that is being parted out) and then just swap either the entire rail or just that 1 injector. I mean another injector could go bad, but at least I would have a few spare ones.

The car isn't getting newer, so these problems are expected - I just wish I was the original owner so I would have taken better care of the car.


Thanks!
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#6 Old 08-14-2009, 04:48 PM
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It sounds like the injector is electrically open. That means it is closed and should not be spraying any fuel. The "l" reading, by the way, means open circuit. If you connect both meter probes together you'll notice that it will go to "0" ohms. Just the fact that you got a meter reading on the other injector(s) means that you're doing the test correctly. All the injectors should roughly read the same, about 11-13 ohms.

I say to go ahead and buy the fuel rail with all the injectors attached. Just confirm that the injectors are spraying correctly before locking down the fuel rail since some injectors are bound to get stuck closed due to internal rust in the pintle area.



'94 Nissan Altima SE, 5spd.
Erebuni 905, Turboing, Hotshot CAI, UR Pulley, Calum ECU,
HUD & ATC retrofitted, DEPO lamps, NGK Ignition wires.
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#7 Old 08-14-2009, 05:06 PM
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Thanks for the suggestion. I'm wondering if I can test the injector connector terminals while the car is running? I know that it's probably better to use and oscilloscope given the frequency of the open/close signal (ie, pulse width) that comes from the ECU - but is there any type of test I could do with the standard multi-meter that may at least tell me:

1) The ECU is still sending a signal to the injector confirming it is not a wiring issue
2) If I get the same reading on all 4 terminals then I know for sure it is the injector

I am asking, since I am thinking this may save me the trouble of having to swap the injector and THEN realize it was the connection?

If the injector gets a DC voltage signal, AND if the multi-meter is sensitive enough to show a reading that flips back and forth between plus "X" volts and 0 volts and I can read that voltage, I would know that the wiring from ECU to the injector is fine - does this make sense, or am I reading into the issue too much?
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#8 Old 08-14-2009, 06:58 PM
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The injector pulsewidth is too fast (mSec) for the standard meter to pick up. Though there are some multimeters which also measures pulsewidth or has a logic probe setting. Those could be used for testing whether the ECU is firing the injectors. You could also try using a noid light or connecting a spare injector while listening for clicking sounds. And you can connect a long screwdriver handle to the injector and listen for clicking while the engine is running. If you disconnect and reconnect the injector harness while listen to it you should be able to tell whether its working.



'94 Nissan Altima SE, 5spd.
Erebuni 905, Turboing, Hotshot CAI, UR Pulley, Calum ECU,
HUD & ATC retrofitted, DEPO lamps, NGK Ignition wires.
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#9 Old 08-16-2009, 02:16 PM
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So, I changed my injector - what a pain in the arse!! I bougt a rebuilt one for $90, and i am glad i did bc took me forver to get it out. I could not remove it without taking the rail out - the plastic housing on the injector cracked while I tried to use pliers to twist it out - that sucker would not budge.

The new one went in pretty easily - good thing I didn't try to go and get it out from the scrap yard - it took me about 2 hours to do everything - then again I was being thorough and changed the plugs, wires etc.

I think these are the original injectors that's why they were so tight. I'll be cleaning out the throttle body bc i am sure it's all black and nasty from running on 3 cylinders and running rich for the last few weeks.

Thanks again for your help!!
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#10 Old 08-17-2009, 12:37 AM
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You changed the injector(s) o-ring when installing the new one correct?

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#11 Old 08-17-2009, 11:06 AM
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Luckily the rebuilt injectors came with the necessary O-rings. I just lubed them up a bit before putting it into the rail.

Not sure if it was a combination of the new Bosch 4 platinum plugs, a new set of NGK spark wires,but the car seems to have more pep now and smoother shifting (yeah..its an auto :P)
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#12 Old 08-17-2009, 03:56 PM
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Good stuff, glad it worked out for you. I would of stuck to NGK as far as plugs go but at least the car is running great.

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