Help replacing injectors

[splat55]

Okay guys,
Well, thanks to you guys I found the inline fuel filter that needed to be replaced on my '99 K3500 7.4. I wanted to replace it before installing new injectors.....which I have never been done. I've always only worked on older iron that had carbs. Anyway, I figure the injectors are under the aluminum thing that sits on top center of the engine...where a manifold and carb would be if it were a conventional carb engine. Is there anything here on the website, or online that will tell me step by step how to get to the injectors. I mean, I can see bolts that hold down the aluminum peice, but there are other peices around it that need to be removed to get to them. I can see that I will have to remove part or all of my K&N filter assy...but there are also some cables, accelerator I believe, and some other goodies. Just hoping someone can point me to a " step by step " diaghram or something just so I don't screw anything up along the way. Any help is appreciated.
Thanks to you all for a very helpful and informative site.

[truckdude239]

ummnot sure about that but can i ask why you are replacing the injectors?

[clinebarger]

Im also curious about why you need 8 new injectors. You got to remove the upper intake manifold.



Upper Intake Removal Procedure

1. Disconnect the battery negative cable from the battery.

2. Remove the intake air resonator from the throttle body.

3. Remove the air cleaner intake duct from the throttle body.

4. Remove the crankcase vent tube from the throttle body.

5. Remove the PCV valve from the valve rocker arm cover.

6. Remove the EGR pipe from the upper intake manifold.

7. Remove Left and Right Side Secondary AIR Injection Pipe. If so Equipped.

8. Remove the ignition coil from the intake manifold.

9. Remove the throttle body from the upper intake manifold. set aside

10. Remove the EVAP canister solenoid valve.

11. Remove the number 8 spark plug wire from the distributor.

12. Remove the upper intake manifold bolts.

13. Remove the upper intake manifold and gaskets.

14. Clean all gasket surfaces excessive carbon deposit from the exhaust and the EGR valve passages.

Injector replacment.
Disconnect the 8 injector electrical plugs.
disconnect the two fuel lines.
remove the 4 injector rail bolts. (I think theres 4 chould be wrong)
remove injector rail with injectors.
Move to a work bench and change the injectors & o-rings

Reverse the procedure to install noting the following.

Coat a minimum of eight threads of the intake bolts with thread sealant.

Tighten the intake bolts in sequence to 8 Nm (71 in. lbs.).

Re tighten the bolts in sequence to 18 Nm (13 ft. lbs.)

[splat55]

Hey guys, thanks for the info thus far. I am replacing the injectors because they have been diagnosed by a few to being worn, and leaking into the cylinders after the truck is run for a while then shut down.

[truckdude239]

umm okay thats a new one to me. i can see one or 2 injector doing that but not all 8

[splat55]

Hi Dave,
Yeah, I don't really know a lot about injectors....but, there are a lot of guys that do, and well, the one common that I found when talking to some guys that sell, rebuild, etc. injectors was that it was pretty common for the original injectors that came on my 7.4 to fail....maybe not all of them at once, but, I was told that if I had to replace a couple of them, then the others won't be far behind....and buying a set of injectors is a lot less costly then buying them one or two at a time. I got an excellent deal I believe. I could have purchased them anywhere, but I dealt with Jon at The Injector Connection. They have a dot com address with the same name. I did my research, and was offered an excellent deal and Jon was excellent to work with, answered all my questions and even called me to clarify a few things. But most importantly was the fact that if I was going to replace 2 injectors, I could count on replacing more of the problem original GM injectors that were specific to my engine.

Originally Posted by truckdude239

umm okay thats a new one to me. i can see one or 2 injector doing that but not all 8