91 Nissan GXE fuel injector replacement

Usually, while you have the plenum off it's a good idea to at least replace the 3 injectors at the back.

It's a good time and labour saving thing.

I did all 6 of my injectors on my '91 SE (same as your GXE). Why are you only keeping it for another 10K? You'll get another 50-100K out of this engine.

First off, your mechanic is grossly overcharging for the injectors. I bought all 6 from the dealer for a little more than $600, or $100 each. $165 sounds WAY too high. His labor is low, but he's definitely making up for it in parts. I was quoted around $1200 from a dealer ($700 parts*, $500 labor). Your quote is almost $1200, so there's no bargain being had. Make sure you get the dealer injectors. There's no advantage to aftermarket.

• extra parts include the new gaskets and various tools and cleaners (gasket remover).

See if he'll charge you $185 for labor even if you provide the injectors. I bet he won't.

Second, I wouldn't replace just one. All 6 injectors should match. Some have a Blue dot, and some have a Black dot. They should all be the same or the engine will have trouble adjusting the air/fuel mixture. You can try matching the new one with the old ones, but may not be able to.

Third, you can do it yourself. It is not difficult, but requires a somewhat deft touch, and it is time consuming, especially if the engine has never been taken apart. Removing the old gaskets can take some time. The only really difficult parts were removing the old / installing the new injectors into the fuel rail. They are very snug, and you don't want to roll the rubber ring/seal out of it's groove, or you'll be leaking fuel. You also don't want to force them in, because they are somewhat fragile, and at $100 per, aren't something you want to break. The manuals suggest moistening the rings with fuel to help them slide in, but you could probably use petroleum jelly.

If you choose to do this yourself, here are a few suggestions.

1. Replace the fuel filter. You will already have taken the pressure out of the system. It's very cheap and easy.
2. While you've got the intake system off the engine, go ahead and take off the valve covers and replace the gaskets. They are cheap, and it's maybe 16 bolts extra work.
3. Also, buy a throttle body gasket so you can take it off and clean the TB (you'll need special cleaner). You don't have to do this to finish the injectors, but taking it off does make it easier to handle the upper intake manifold.
4. Check the performance of the PCV valve. It's very cheap and easy to replace.
5. Make sure you either mark all the vacuum tubes/electrical connectors or know where they go. You will likely get a Check Engine light if something is disconnected.
6. Might as well replace the spark plugs. All 6 will cost around from the dealer.

If you do all these things in addition to the injectors, you'll add maybe $75-100 in parts. But all of them will add to the performance/reliability of the engine. Both my valve covers leak slightly, and the car ran much better after the TB cleaning. The fuel filter, plugs, and PCV valve need to be replaced regularly anyway, so do it now.

It will help if you have another vehicle available in case you need to go get a tool or parts. Plan on 2 days to finish this. It will take some time to get it all apart and cleaned/prepped for the replacement. It should go back together fairly quickly.

You MUST use a torque wrench to do this job properly. And you'll likely need 2 of them, because the torque ranges are too far apart for any 1 wrench. The fuel rail is one part that has a very low torque setting, but is pretty critical. You can probably rent them if you don't own them.

I used both the Haynes and a Chiltons. Between them, they had everything I needed. I found the Chiltons to have better pictures, and slightly better descriptions of what was next.

If you have any questions, I'll be happy to help.

Bill G '91 SE Auto

Thanks for the advice. I really don't want to change all 6 since the car has limited life left (I think) but at least the 3 on that rail is a darn good idea. Thanks for the info.

Inline......

I did all 6 of my injectors on my '91 SE (same as your GXE). Why are you only keeping it for another 10K? You'll get another 50-100K out of this engine.

--- Didn't know that these things run so long. I am the 3rd owner and owner 1 (new-100k miles) drove it like he stole it from what I understand. Redline every gear, dumping the clutch, drifting, etc. so I am unsure how much life is left with that kind of initial abuse. Also, the front input bearing on the trans is horrifically loud, car was brought from Chicago so it's mostly rusted out.

See if he'll charge you $185 for labor even if you provide the injectors. I bet he won't.

--- already tried that. No dice.

Second, I wouldn't replace just one. All 6 injectors should match. Some have a Blue dot, and some have a Black dot. They should all be the same or the engine will have trouble adjusting the air/fuel mixture. You can try matching the new one with the old ones, but may not be able to.

--- I looked at AZ's website and again am looking to save a few bucks wherever possible. They do sell the blue and black dot injectors seperately so I was hoping to take out #4 (now the entire rail) and buy

3 more that were the corresponding dot that I took out. No hope in getting some from a low mileage wreck in the junkyeard eh?

Third, you can do it yourself. It is not difficult, but requires a somewhat deft touch, and it is time consuming, especially if the engine has never been taken apart. Removing the old gaskets can take some time. The only really difficult parts were removing the old / installing the new injectors into the fuel rail. They are very snug, and you don't want to roll the

rubber ring/seal out of it's groove, or you'll be leaking fuel. You also don't want to force them in, because they are somewhat fragile, and at $100 per, aren't something you want to break. The manuals suggest moistening the rings with fuel to help them slide in, but you could probably use petroleum jelly.

--- I read about this in the manual but all it talked about were O rings. I assume I need the O Ring set from AZ also ($10). The other gaskets, are they the intake gaskets under the plenum? And yes, this engine is severly rusted and never been taken apart so a lot of PB blaster and time will be necessary I imagine.

If you choose to do this yourself, here are a few suggestions.

1. Replace the fuel filter. You will already have taken the pressure out of the system. It's very cheap and easy.

--- Just did that. At least that was a piece of cake

1. While you've got the intake system off the engine, go ahead and take off the valve covers and replace the gaskets. They are cheap, and it's maybe 16 bolts extra work.

-- considering the rear main on the engine, not sure what this would help, but it's a good idea anyways.

1. Also, buy a throttle body gasket so you can take it off and clean the TB (you'll need special cleaner). You don't have to do this to finish the

injectors, but taking it off does make it easier to handle the upper intake manifold.

-excellenti idea. 190k it's gotta be carboned up pretty good.

1. Check the performance of the PCV valve. It's very cheap and easy to replace.

--- I will do that too as they are cheap.

1. Make sure you either mark all the vacuum tubes/electrical connectors or know where they go. You will likely get a Check Engine light if something is disconnected.

--- I didn't think there were that many. Looks like an EGR valve of some sort, a PCV system and a few throttle cables.

1. Might as well replace the spark plugs. All 6 will cost around from the dealer.

---already did, plugs, wire, cap and rotor

It will help if you have another vehicle available in case you need to go get a tool or parts. Plan on 2 days to finish this. It will take some time to get it all apart and cleaned/prepped for the replacement. It should go back together fairly quickly.

---I have an AZ right near my house and can do without the car for a few days so that is the main reason I want to tackle this myself.

You MUST use a torque wrench to do this job properly. And you'll likely need 2 of them, because the torque ranges are too far apart for any 1 wrench. The fuel rail is one part that has a very low torque setting, but is pretty critical. You can probably rent them if you don't own them.

---I have a good foot pounds wrench that goes from 20-100 and then a heavy duty one for 100+. I'll go buy an inch pounds torque wrench.

I used both the Haynes and a Chiltons. Between them, they had everything I needed. I found the Chiltons to have better pictures, and slightly better descriptions of what was next.

--OK, well that's good to hear. Buddy of mine has factory service manuals for a 96 so I might go borrow them as they couldn't have changed that much over the years.

If you have any questions, I'll be happy to help.

---Thanks Bill, I totally appreciate it.

Well, at least mechanically it's probably got lots of life. The rust situation may change all that. I'm used to living in no-salt country (Oregon), so my '91 doesn't have a speck of rust anywhere. The tranny situation could be pricey though.

BTW, you didn't answer the question. Why get rid of it in 10K miles?

If you're not replacing all 6, then why do 3 instead of just the bad one? Doesn't seem to make sense.

They should come with the injectors. At least the ones I bought from the dealer did. Don't buy them from AutoZone, just get them from a dealer. There's no advantage, other than maybe saving $15 per injector. And that, at least to me, isn't enough reason to not get OEM.

Yes, those gaskets. You're not likely to run into rust issues with the gaskets, but after running for 190K miles, they are going to be pretty well adhered to the manifold parts.

Mine both have very slight leaks after 180K miles. I figure the gaskets are very cheap, and with the upper intake manifold already off, why not do it.

You'll notice a big difference in acceleration. It may take a little while for the O2 sensors and ECU to figure out the new fuel mixture, but not long (a few miles).

There are a few vacuum tubes as well. It's not that many, and I didn't mark mine. It's pretty obvious where they go, and very difficult to put them in the wrong place. It's mostly so that you don't forget one.

Won't need the 100+ wrench, but will need an inch-pounder.

Well, the engines are different. Check your local library and see if they have a Chiltons.

No problem whatsoever. I'd done the whole water pump/timing belt/cam shaft seal repair with a friend (and later by myself), but this injector replacement was my first big solo project. Just be thorough, follow the steps, and you'll be fine. I was very satisfied when the car started right up and worked perfectly.

Good luck!

Bill G '91 SE Auto

Bill,

Thanks again for all the info. I had a few issues with corroded vacuum lines (will replace most of them) and the EGR valve breaking loose. I did manage to get the plenum off and the lower intake plate. It took 3

6mm allen wrenches and 1 foot long cheater bar to break the hex bolts, but I got it off. Next stop to the auto parts store I will get a 3/8" drive allen socket. The gaskets were so crusted, they peeled right off so I consider myself lucky. Now for the unlucky part... I am down to the fuel rails, 2 rails joined by rubber hose, passenger side looks like fuel delivery and driver side liikes like a pressure regulater/return. There are 2 screws next to each injector. I am assuming these have to be removed? My only saviour on this car is that so far all screws have had a hex head that I could get a socket on. My luck ran out here and those screws are impossible to get out withough drilling or using an easy out. I was mistaken before too about the engine never being apart as the #4 injector's screws are totally stripped. Do these have to come out or can I take the fuel rail assembly off and then get these onto a bench where I can drill more dramatically?

Once I get these injectors out, I can head off to the dealer and get new ones. I will definitely get all 6 as I have no desire to do this again. The plenum and intake assembly are coated with oil and gunk, can I use standard carburator and choke cleaner on these parts? Cleaning is free and I prefer to clean whatever I can.

Thanks again for all your help. I totally appreciate it.

Derek

You can use a dab of liquid dish soap to help slide the new lines on. I had a few connections that were corroded, but the soap helped alot.

Forgot to mention you'd need that. The allens are fine for removal, but you'll need the socket to torque them back correctly.

I'd try some penetrating oil or something similar rather than drilling.

IIRC, there's a small bracket that goes on top of the injector which has those 2 bolts you're referring to. Yes, you can remove the entire fuel rail first, then tackle the other screws/bolts. I actually had trouble with 2 of the injectors not seating in the rail, and used the brackets to kind of push them into place. I don't recommend this unless it's a last resort.

One thing to be careful of, when you're re-installing the fuel rail, and torquing the bolts down, be very aware of the torque wrench. I overtightened mine the first time because the little "click" the wrench makes when reaching it's proper torque is much more difficult to hear/feel than on the bigger wrenches. Luckily, those rubber gaskets on the rail weren't damaged, so I was able to back off the bolts and re-tighten them properly. Just be careful.

Yep, that was my thinking after I'd gotten it apart. You wouldn't have as much trouble the next time though. Everything will come apart much easier, and you'll know what you're doing. But the fuel rail will still be a pain in the ass no matter how many times you do it.

Sure, those will work. Only the throttle body needs "special" cleaner. I cleaned the manifolds as well when I did it. I used some electrical cleaner because it didn't leave a residue (like TB cleaner). Both those cleaners should also work.

You're totally welcome. I've gotten plenty of help from others here, so I'm more than willing to help another DIY'er.

BTW, after this you will have a debt to society (i.e. this newsgroup) to help others with this repair. ;-)

There are fewer and fewer 3rd Gen owners here, so we've gotta stick together!

Bill G

Bill,

You directions were right on so far. The dealer wants $125 for the injector and $5 for the o rings. Even AZ wants $120 per injector so I placed an order with the dealer. Parts alone ran about $1k. Almost what I paid for the car. I did have one problem with the caps that hold the injectors in and seeing how the screws were already stripped and rusted I managed to break one of the covers to the injector. Dealer ordered the part @ $25 and I get it Wed. I will then start the fun reassembly process and hopefully get it running by the end of the week. Haynes manual is worthless when it comes to removing the injectors so I just massaged them out with a BFH. Thanks again for all the helpful info.

Derek

Keep us posted after you've finished. Oh, and be prepared for some serious acceleration once it's all back together. My car just jumped off the line afterwards.

Bill G

Bill,

One more question for now. Is it possible to put the injectors back in, and turn the key to let the fuel system pressurize to look for leaks? I didn't remove the rail from the fuel lines, but just unbolted it and pick it off the intake. That gave me enough clearance to whack the injectors out. I am afraid of fuel leackage and rather find it before I get the plenum back on.

Thanks again,

Derek

I don't see why you couldn't. You're likely to get numerous ECU Codes, and one of them might be "Injector Leak" that you may not physically see, but may be happening. That code is going to get lost in the shuffle. Another thing, I'm not sure how this will work if you don't have the injector connectors attached. I think by default the injectors are "closed", but I'm not positive.

NissTech, do you have any thoughts on this?

If you do it, make sure the fuel rail and injectors are bone dry first. And make sure you have excellent lighting when looking for leaks. I'd even think about using a magnifying glass. And give it several minutes in case the leak is a slow one.

And I'd be a little more careful putting it all back together. The system under pressure may be delicate and more prone to "injury". Obviously, you won't be able to relieve the fuel pressure until it's back together.

Man, that's a bad description. But it's exactly what I had to do. Getting those old bastards out really sucked arse.

I was too. But it all worked out just fine.

Bill G

Bill,

Bill,

Here's my latest update.... I replaced the 6 fuel injectors, 2 valve cover gaskets, thermostat, PCV valve and flushed the cooling system. When reassembling, I did turn the key to pressurize the system once I had the fuel rail back together. The gurgling and sloshing noises were a bit nerve wracking, but once the system pressurized, there were no leaks. Getting the plenum on, I used a q-tip with a bit of dish soap on the insides of all the vacuum lines. They were so old and crusty, they wouldn't slip back on the plenum fittings easily but with the soap, they slipped right on. After complete reassembly and adding coolant the car started right up making horrific knocking and banging noises for about 5 seconds. Once that noise went away, looks like everything is ok now. I do have a couple of questions though.

A friend of mine said to run injector cleaner through it immediately since my injectors were new. Not sure what to make of this.

When engine is cold, I have an off idle stumble from about 700-800rpm under load and in neutral. This might have always been there, but seems worse now. I did verify all vacuum lines were connected and check engine light is not on.

You mentioned earlier that you did the timing belt and water pump. My water pump is original and the timing belt has 100k on it. How hard was that job compared to the fuel injectors?

Many thanks yet again and if you are ever out in the Midwest, drop me a line and the beer's on me.

Reach snipped-for-privacy@hotmailHEAD.com. Remove head before replying.

I didn't at first. But I do run it through maybe every 25-30K miles.

My car definitely had a few quirks for maybe 2 weeks after the injector swap, usually involving RPM variation. But once the kinks were apparently worked out, I haven't had any problems whatsoever. I don't know what's causing it, but maybe just use it for a few weeks and see what happens.

I STRONGLY recommend you do this repair as soon as possible. If you belt breaks, you can kiss the valves and pistons goodbye. It's recommended you replace it every 60-90K miles.

As for the job itself, while the injectors required a lot of finesse, and things were relatively easy to get to, the pump/belt job is kinda the opposite, but not all that difficult. You'll spend alot more time on the ground.

The hardest parts are getting the crank pulley bolt broken loose and maneuvering the upper and lower timing belt covers out and then back in (have plenty of extra swear words saved up for this one!). And then putting the bolts on the covers, ARGHH!!!! (It was MUCH easier the second time I did this repair). There are obviously more liquids involved (gotta drain the coolant). The trickiest part is making sure the timing belt tensioner is installed properly and getting the belt itself installed exactly where it's supposed to go. If you're not sure, read the instructions a few times. The belt MUST be aligned properly. It is clearly marked, and the cam shafts and crank shaft are also marked.

You said you already replaced the thermostat, so obviously won't need to do it again, but you'll probably have to take the thermostat housing off to make this repair easier. It's not necessary, but you may find you have to. No big deal, but you have to put the liquid gasket stuff back on (you'll also need to do this for the water pump). Ideally, you let the liquid gaskets cure for at least 24 hours before putting coolant in and running it.

It sounds like you have access to another vehicle, and this is good. Once you have the engine torn down, check the cam shaft seals and make sure they're not leaking. If they are, this is definitely the time to replace them. You'll have to remove the cam sprockets, then the inner timing belt cover (both are easy to remove) in order to get a good look at the seals. Even if they aren't leaking, you can use this opportunity to clean back there and remove any gunk off the engine.

If you do this, you'll find that you can't get a torque wrench on the back sprocket to tighten it properly. NissTech e-mailed me when I was doing this job after I inquired about it, and his answer was to use the German method, i.e. Gudenteit. Torque the front cam down, getting a feel for it's tightness, then put a socket/end wrench on the back one and tighten it up. The cam sprockets are keyed, so can't be put on improperly, but you CANNOT rotate either one of them or your timing could be off. I would leave the old timing belt on while you loosen the bolts, take the belt off, then off with the cam sprockets. Check for leaks. When re-assembling, put the cam sprockets on, put the old timing belt on again (doesn't have to be lined up, just on), then tighten both cam bolts. This way, if either cam moves when you're tightening, they'll both move, thus keeping them aligned with each other. The belt doesn't need to be lined up for this, just on, so that it will keep them aligned. And use the old one, since this may put undue tension on the belt, and no point in straining the new one. None of this is very difficult, you just have to be careful.

And if you do this job, you should also think about replacing the upper and lower radiator hoses. The coolant will already be out, and you'll have detached part of the upper one. If they are original, then replace them. You can test them after you've drained the coolant. They should be firm, but give a little when you squeeze them. If they feel stiff or spongy, then replace.

Parts: Water Pump - get it from a dealer - DO NOT buy a reconditioned one. Timing Belt - also get it from a dealer Timing Belt tensioner - definitely replace it, with a dealer part. All 3 accessory belts - might as well, they're cheap - can buy these anywhere. Radiator Hoses - Upper and Lower - again, not much money, get them anywhere. Coolant - don't know how old yours is, but it's also cheap to replace. Just make sure you dispose of the old stuff properly.

This is a very common repair, and I imagine most of the regulars here have done it at one time or another. You'll save a good chunk of money by doing it yourself.

Give yourself about 2-3 days to finish this. I've had it done in less than

48 hours, and that included 24 hours of liquid gasket time.

As usual, I'll be here if you have any questions.

Bill G '91 SE Auto

Bill,

As usual, excellent info. Think I might wait til spring to attempt this. From what you are saying, I take it this is an interference engine so time is definitely not on my side. Thanks again for all your help. You certainly make this forum an oustanding resource.

Derek

Hehe, thank you. But don't ask me about any other repairs! These are the only 2 big jobs I've done, so while it may appear that I'm knowledgeable, I'm tapped out !!!

Niss Tech is the real brains behind this ng. He's taught many of us how to do things.

But you're right, this is a very helpful and informative newsgroup. I've been coming here for 5 years or more, and haven't been disappointed yet. Unfortunately, there are fewer and fewer 3rd Gen owners, so it can be a little harder to get info.

BTW, you now have a responsibility to help anyone else who does their injectors on a 3rd Gen!

;-)

Bill G '91 SE Auto