How to Replace Fuel Injectors - A quick step by step

Discussion in 'GM Powertrain' started by Skippy, Dec 31, 2012.

  1. Skippy

    Skippy Member 2 Years 100 Posts

    Hey everyone. I posted this deep in a thread about changing spark plugs, then figured it was worth a post just so folks could find it. As a general rule, fuel injectors don't need much more maintenance than a periodic detergent gasoline (top tier), and/or a periodic fuel injector cleaning through the gas line. In spite of all the advertising that suggests you can get "like new" injectors, cleaning them only removes deposits. Over time, injectors suffer from wear and tear. They have moving parts! Additionally, too many additives can actually increase the port size (resulting in the fuel spray from going from a fine mist to a blob). Leaking injectors will degrade fuel economy (if leaking into the engine), and often will show up as a rich code. For the most part, modern fuel injection engines are able to compensate for the normal degredation over time, but there's nothing like a NEW injector to restore actual power loss resulting from wear and tear. No amount of additive will do that.

    As a general rule, I recommend to my customers to consider changing all their injectors after 80K miles at the first sign of trouble on a single injector, or at about 140K miles if they intend to keep it for 20K+ more miles.

    If you do the job yourself, you'll save a bunch of cash. It's also not a hard job!

    Additionally, its very common (in fact, it's happened in every vehicle I've done at 120K miles or more) that the vehicle will pick up 1-2MPG gallon, as a result of restored power and more efficient burn.

    Why else should you maintain them by replacement? Well, I've seen more than one engine completely shot as a result of a fuel injector failing. A $50 part cost the owner $3500 in repairs. (I was one of those many years ago and just scrapped the thing).

    Again, there are those that would say "if it works, why replace it?" My answer above is the meat. I'd like to add, also, that we all change out spark plugs while they're still working; fuel injectors should get the same love. :)

    Time Cost/value:
    The first time you do this, it'll probably take about an hour and a half, because you'll be slow and careful. This generally takes me about 30 to 45 minutes to do a full injector swap, barring any weirdness. TOTALLY worth your time, btw, as the dealers will charge upwards of $1200 to do this! (injectors will run $350 - $700 genearlly for v-6 and v-8 applications, easy to check, just hit an online auto parts shop)

    Ease of Repair:
    Easy to Medium
    Personally, I think it's easier than many spark plug replacement jobs, because, generally, the injectors are more accessible.
    Usually I only need one or two sockets (8mm and 10mm), but sometimes I find an engine that needs something else. For the most part, though, a simple socket set is all that is needed. Nothing special here.

    Rags, clean motor oil, new injectors, Socket set

    Caution: As with any fuel related repair, make sure you do this in a WELL ventilated place, and no smoking while working on the Truck! It also helps to do this on a CLEANED engine (no gunk getting into the injector slots), and on a cool engine (no burned hands). Make sure the battery is disconnected at the right time, too!

    Start by depressurizing the fuel system. If your truck is equipped with a fuel safety cutoff switches, find it and pull the electrical plug from it. This will disengage the fuel pump. Then try to start the engine (it will turn-over, but not start). This will pull any fuel from the lines and depressurize them.
    Disconnect the battery.

    If you don’t have a fuel safety cutoff switch, you can depressurize the line by finding the pressure check valve (usually on top of the rail) and depressing the valve. This will spray fuel everywhere, though, and is messy. If you have a fuel pressure tester, it’ll come with a valve checker and hose for this purpose making it far less messy. It’s not necessary though.

    Last resort is to pull a fuel line, that’s REALLY messy. Make sure all fuel is mopped up and dry before proceeding. No sparks here!

    Next, pull any components that restrict access to the fuel rail on the engine. On a V-8 you’ll need to do this for both sides of the engine, as the rails will be on both sides. Most Chevy trucks will need the following removed: engine shroud, air intake, vacuum tubes, electrical plugs and bolt-on engine accessories.

    Next, disconnect the fuel rail bolt securing the rail to the intake or engine.

    Disconnect the electronic plug from each injector.Push the plug away from the rail.

    At this point you’re ready to pull injectors (not so bad, huh!) Basically, since you’re doing all the injectors, just pull the fuel rail directly away from the tops of the injectors (they’re just held on with O-rings). You may need to rock the rail slightly. The rail will pop right off all four injectors will a little pulling.

    Remove the injector from the engine by grasping the injector head and pulling it directly away from the engine. You may find again, that it needs a little rocking.

    Once pulled, make sure that each injector has the O-ring on the bottom and top. Otherwise, check the rail or hole. The O-rings are larger than the hole in the engine, so there’s no worries about it slipping down inside, but occasionally they do remain in the slot.

    On the new injectors, check to see if they come with pre-installed O-rings. They should. If not, you’ll need to get O-rings on them (they’re cheap, btw, but you’ll need to get new ones from the auto parts store..> DO NOT USE OLD O-Rings as they’ll have micro-tears or will be hardened, not making a great seal. In fact, it’s a good idea any time you remove the injectors from the rail or engine to replace the O-rings).

    Before putting the O-rings on, lubricate them with new motor oil. The goal is to ensure there are no micro-tears in the O-ring that will cause leaks later. The O-rings are fairly flexible and can be either rolled onto the injectors or pressed into place. If the injectors come with the O-rings on, lubricate the O-rings with motor oil while the O-ring is in place.

    Put the injector back into the engine by pushing it nozzle first into the hole. Rock it slightly. You’ll feel a slight “pop” as it seats. This is normal. When correctly seated, the injector will resist light attempts at removal. Seat all four injectors in the engine on each side before attempting to connect the rails.

    Connect the rails by seating all four injectors under the ports at the same time, then just press downward. You’ll likely have the same popping feeling again, and as with the engine, properly seated injectors will resist removal.

    Smear a liberal amount of dielectric grease on the injector plug port (the grease will protect the electronics from corrosion and water). Connect the plug to the injector.

    Reconnect the fuel rail retaining bolt or screw, and replace any accessories, intake, vacuum tubes, etc. Don’t put on the engine shroud just yet.
    Reconnect the fuel-safety cut-off switch, if you used this method. Reconnect the battery.

    Prime the fuel system by turning the ignition key to the “start” position a few times (with several seconds in place). You’ll hear the fuel pump prime the lines. Do this at least 3 times to pressurize the fuel lines.

    Inspect the engine compartment for fuel leaks at the injector rails. If you have one, an O-ring isn’t properly seated. Remove the rail and replace the O-ring (as it’s likely been damaged in the process). I’ve never had this occur, but I always check just in case. No use having an engine compartment fire over something as silly as a badly seated O-ring!

    Turn off the engine and install the plastic engine shroud. Close the hood and enjoy restored HP, mileage and engine longevity!


    Last edited: Jan 2, 2013
  2. kinson33

    kinson33 Member 1 Year 100 Posts

    Where would you recommend to look for injectors? 700 for set of 8 pretty typical for the 5.3?
  3. Enkeiavalanche

    Enkeiavalanche Loving the Outdoors Staff Member 5+ Years ROTM Winner 5000 Posts

    Nice write up... :great: Any pics of it being done on a 5.3 or 6.0?
  4. PantheraUncia

    PantheraUncia Epic Member 5+ Years 1000 Posts

    I thought about doing this in my truck..... generation 1 5.3L with 220,000 miles on it, but pictures would really help although the wright up is excellent, and yes the after market injectors are about $93-$120 unless you get the delco ones from the dealer or amazon....... and that is per injector and we need 8 of them :-(
  5. Skippy

    Skippy Member 2 Years 100 Posts

    It depends on the injector you're looking to replace. Basically, you can find a wide range of injectors (generally OEM style replacements are a bit cheaper than the ones made for higher performance applications... as with anything).

    For example, looking on Autozone's website, injectors run anywhere from $45 for a single to about $120 a single injector. When I do them, I usually float the middle road paying about $75 an injector before shop discounts. I don't have a brand preference, used a bunch, everything from Accel to BWD for OEM applications.

    Basically, you can find them for as little as $400 (even lower if you look hard for a set), upwards of $1000. $700 is pretty typical for a V-8 application, yeah.


    - - - Updated - - -

    Sorry. While I've done a bunch of them, I've never taken pictures of anything other than a single injector to show a customer something over e-mail.

    Next Chevy I do, I'll be sure to grab some.

  6. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    I've learned that there are some places to skimp and some places to avoid skimping. For example, brake pads and rotors are NOT places to skimp, as the cheap ones don't last or wear well. How does this play in the injector world? Do the cheap ones need to be replaced that much sooner or do they wear or perform poorly? How long can they be expected to last before it's time to put another set in? Basically, what makes one injector 45 bucks and another injector 120 bucks?
  7. Conlan Rose

    Conlan Rose Epic Member 5+ Years 1000 Posts

    I can't ever find OEM injectors for my truck only MPFI "upgrade" kits. I want a OEM SFI kit if I'm going to spend the time to do it. Also does this process only work for 1999-2013 trucks with the Vortec 4.3, 4.8, 5.3, 6.0, and 6.2, not the 1996-1998/1999 Vortec 4.3, 5.0, 5.7, and 7.4.
  8. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    I called GM SPO today. My injectors are $73.99 each thru GM. I can get them for $62 each on amazon. Looks like I will be getting some money together for this replacement. Not cheap!

    - - - Updated - - -

    @Conlan Rose , I took the liberty of calling SPO with your vin since I had it from your broken spark plug issue. The GM part number for your injector is 17091432 . They are $75.75 each thru GM or $59.59 on amazon.

    The MPFI kits are around $350 on amazon. In my opinion that would be the way to go. You get all the injectors and a spider for $350
    Last edited: Jan 4, 2013
  9. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    In reading through it, I do believe he is talking about a typical MPFI system. On our OBS Vortecs, they used a CSFI system, where the "injectors" (poppet valves) feed off of a central "spider" inside the upper intake.

    I would suggest you reconsider the MPFI upgrade, especially if you are planning to replace all 8 injectors/poppet valves. One of the reasons GM offers the upgrade (especially if they've also decided not to offer the old style) is that a lot of people had trouble with those poppet valves. The MPFI upgrade kit uses more typical injectors that most consider more reliable than the stock poppet valves.
  10. Conlan Rose

    Conlan Rose Epic Member 5+ Years 1000 Posts

    Ok, I'll think about it. Do you think I will see an improvement in mpg or power? And are the totally plug and play no flashing of the ECM.

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