How to Change Your Injectors
NOTE: There is no need to change your injectors.
Nissan has recalled all 84-89 300ZXs in the USA and will replace the injectors
and some other associated components free of charge. Make an appointment with
any dealer if your car has not been done yet. If you're unsure whether
your car has been done yet, call any dealer with your VIN handy and they
will look it up for you.
The early 300ZXs' injectors have a habit of leaking around the seam where
they are pressed together. If they are not changed once they start to
leak, your car will burn.
Since this is not good, you will want
to change your injectors once they start to leak. "But how will I know when/if they
leak?", you ask. You will smell it, trust me. Anytime you smell gas in your car,
check around the injectors and fuel rail, as this is where virtually all leaks
start. It is a good idea to carry a fire extinguisher in your car, just in case.
If your car catches on fire, unless you are really lucky, or near a fire station,
it will be a complete loss.
Simply call your local Nissan dealer for information on
what to do to have the recall work done on your car.
It's not really hard to change the injectors, just
takes some time. Here is how you do it:
This is not that big of a job, give yourself a weekend and make sure you have all
the parts before you begin because the average person dosen't want to have to
remove the manifold again. The going price around here is $900 for the whole
job, parts and all(factory injectors) You will end up spending about $300 total if
you do it yourself(+ $130 if you replace the pressure regulator)
- Buy the new injectors. They usually run around $30-40 each
(Unless you buy Nissan ones which are $100 a pop), and of course
you need six. It's also a good idea to replace the pressure regulator now.
I've been told that when it goes bad, it can take the air flow meter($502!!)
with it. I don't see how this could happen, but it did on mine.
It's semi-pricey at $130, but good insurance. I highly advise it.
Buy the gasket that goes between the two halves of the intake
manifold. It costs ~$5 at a Nissan dealer. You will also need a few feet of
high quality 5/16 feul line. Don't skimp on the hose, the best stuff you can
buy won't cost more than $2/foot. Do not, under any circumstances use cheap
"no name" brand hose from Auto Bone, Western Auto, or somewhere like that. They
buy the cheapest stuff they can find. I would reccomend you use Goodyear hose
exclusively for this job, as some of the lines are not accessable without
semi-major dissassembly. Also get some good quality hose clamps, locking ones
are ideal. I would also reccomend that you change the fuel filter during this
proccess. You will also need a set of injector o-rings. There
two on each injector, one large and one small. These are the o-rings that seal the
injectors to the intake manifold.
- Relieve the pressure in the system by letting the car idle
after unplugging the fuel pump. It will die in a few seconds from a lack of fuel.
- Remove the upper half of the intake manifold, this is not as bad as it sounds.
Unplug/disconnect everything on top of the engine, labelling if you need to,
and work the manifold out through the rat's nest of wires, being carefull not to
rip any of them out.
- Immediately stuff some rags into the intake ports to prevent stuff from falling
down there. This is bad if it happens. Your engine is meant to run on air and gas,
not air, gas, chunks of gasket material, and a few stray nuts, bolts and washers.
If anything should fall in there, be sure to remove it before re-assembly. If it is
not retrievable, then you will have to, um, dissassemble the engine.
- Unplug and unbolt all the injectors. Disconnect the three fuel lines that
connect to the fuel rail. The entire injector rail will now lift up and out,
injectors and all. Also be sure to remove the old injector o-rings.
- Very carefully cut the injectors off the rail. Use the sharpest razor blade you
can find. Try to avoid cutting/scratching the mating surface on the fuel rail, as
this may cause leaks in the future. Blow out the feul rail to remove the ten years
of crap that has built up inside, and any rubber shavings you may have missed.
- The new injectors should have a short section of feul line already pressed
onto them. The injectors are then pressed onto the rail. This sounds easy, but is
very frustrating. It is an extremely tight fit, use a little gas as a lubricant
and take your time. The quality of work is what determines how long these
injectors will last. I always put a small hose clamp on this short section of line,
closest to the fuel rail for extra insurance.
- Put the new injector o-rings in place, the large one on the injector, the
small one in the intake manifold, and set the fuel rail in place, being careful
not to damage the injectors on the way in. Do not force anything into place.
- If you have trouble getting those little spacer blocks to stay in place,
tape them to the injector retaining rings in the appropriate orientation.
- Torque the retaining rings down to the specified torque. This is something
like 3 lbft, it is a VERY LOW TORQUE. Use a torque wrench, borrow one if you
don't have one this sensetive. These parts are very sensetive, too tight or
loose and air will leak around the injectors, which will require dissassembly
- Replace all fuel lines that are not easily accessable at this time. Also
replace the fuel filter now.
- Scrape away the stuck on gasket material from the mating surface of the two
manifold halves. Bu sure it is clean enough to provide a good seal for the
- Replace the upper half of the intake manifold and re-attach everything you
disconnected, making sure you removed the rags you stuck in there, and making
sure the red rings on the gasket are facing downwards. Re-connect everything you
disconnected, not forgetting the fuel pump.
- turn the ignition on and let the car sit for a few seconds until the fuel
pump cuts off, this means the feul lines have reached operating pressure. Start the
engine, it will be hard to keep it running at first due to all the air in the fuel
lines, but should be fine in less than a minute.
- Carry around a fire extinguisher for a few days to make sure there are no
leaks under the hood. It is a good idea to carry one around all the time.
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