Let me start with the details. I purchased my truck nearly 2 years ago from our mechanic at work. While he had the truck he put in a full set of injectors purchased from International. When I purchased the truck I had the diesel mechanic from the local dealership make a diagnostic drive with me because of an issue I had that turned out to be a MAP sensor. While on the ride he pointed out that I had a fuel knock that was probably caused by low fuel pressure. After researching the 7.3 I found that the #8 injector on the late '99 was supposed to be different from the rest. I purchased the correct injector and the mechanic at work changed it while I observed. While changing it he noted that fuel would dump into the cylinder because there was no drain on these engines, yes I later found that he was wrong. After installing he said we would need to get the fuel in the cylinder pushed out the exhaust before it would run. He turned the engine with a wrench a few time and would have me try to turn it over with the switch. If it tried to bind I would stop immediately and would turn more with the wrench. At one point it made a loud popping sound. After doing this for a while it would finally turn over freely and cranked. Still had the knock. Since then I have installed the Riffraff Gen 1 FRX and HPX, Fuel Gauge that shows I have 64-65 psi, then did the in-tank mod deleting the mixer valve and screen, a lifter pump w/ pre filter. I have since found that the mechanic I purchased from did not torque anything on the injectors, and that the knock started after he installed the full set of injectors. I have not had any mechanical issues with the engine since I have had it, just the knock which keeps raising question in my mind. I am healing from shoulder surgery and in a couple of months planning on installing a Gen 2 FRX, torquing the injectors properly, and doing the .50 cent mod. Based on the information given do I need to check or do anything else while I am in there. The set of injectors he put in has 3 years and less than 20k miles on them. I am not burning any oil. there is no smoke. I have kept oil, oil filter, and fuel filter changed since I have owned the truck. I may never get rid of the fuel knock?? Truck runs good. gets 14-15 mpg which does not seem bad for a crew cab long box.

 

I don't know much about the PHP, can yours select different tunes? I have elevated knock in my higher HP tunes because the ICP is raised. I use the stock tune in residential areas because it is so much quieter, then I use the "Quiet" tune (I call it the stealth tune) at the coffee window. The quiet tune sounds like a 2012 6.7, but it doesn't smell like one - I have to limit the use of this.

 

You say Fuel pressure is 64-65. Is that at idle or WOT? It needs to be tested at WOT even better if you can out a load behind it. That being said, some of these things just have that injector knock. I've got 175 SS injectors, a full fuel sys and I still get that inj knock. I think my next mod will be some dynamat under the rubber floor mat!

Barney

 

My last XL was loud, my buddies XLT is a bit quieter, My Lariat is even quieter...I think insulation has a lot to do with it. I haven't heard two 7.3's that sound identical. The noises used to drive me nuts thinking something was wrong, not so much anymore.
Barney I think Dynamat is a great idea being that your truck started life as an XL IIRC

I have the HPx and gen 2 FRx and I hear different noises everyday.

You said that the injectors were purchases from International. Are they the correct code injectors for your truck? If they happen to be single shots that's where your noise is coming from.
I thought......and I may be wrong, but I thought the injectors used in International T444E's were single shots Someone correct me if I'm wrong.

 

You are correct Sir! was an XL now its a XXL!

Barney

 

You are suppose to evacuate the cylinder by vacuum or with the glow plug removed turn over the engine. Sounds like the engine was hydrolocked which could cause some problems.

Sounds like Frank may of hit the nail on the head. Hopefully that's the issue.

 

Here is some injector info from Clay's site. With the FRX from my understanding you shouldn't need the LL in #8. Someone can correct me if I'm wrong.

Injector Description:

AA - '94-'97 Non-California trucks. They are all 90cc injectors and are single shots.
AB - '97 California, and all Early '99 trucks. Split Shot injectors that flow 130cc of fuel.
AC - Came in high torque version of the T444E and didn't come in any Powerstrokes. They have the same internals as the AB injectors with the exception of the single shot plunger and barrel and are 160cc.
AD - These are found in all late '99-'03 Powerstrokes and T444Es, and are a Split Shot Injector
AE - Long lead AD injector that was used to cure a "cackle" issue.

 

Yeah, your mechanic made more work for himself than he needed... all he would've had to have done was remove the glow plugs, install the valve covers, and turn the motor over by shorting the starter relay. As for the noise, these trucks make all kinds of noises and tuning usually adds to it. If it is fuel/combustion-related, I would imagine it would go away when the motor goes into decel when you coast down a hill.

 

It is 6 position

 

International would use their part # and not Fords. We run a lot of International concrete trucks at work so that is why he bought directly from International. They could be single shot. Can hear it at idle sitting in traffic but not really while driving.

 

Holds pretty steady at that psi, may push just under 68 when under load

 

You may just have one bad injector that knocks at idle. You need somebody that can turn off one injector at a time to see what one is knocking. I had that done on mine and it was number8. I didn't change it yet but put Clays FRX on and it cut the noise in half. Every once in a while it dose come back hard but goes away. I will change it, but would really like to go with some stage two's.

Chet

 

Previous owner said it started when he put in the new set. I had him replace #8 with the proper one, did get a little quieter or maybe I just wanted it to. Put on the Riffraff FRx and I could hear the radio but still had a knock. Tried the other stuff I mentioned earlier. Finally decided to get a better radio,.
Surfing threads I came across one about torquing the injector hold down bolts and a few other things. Was talking to previous owner about it, we work together, and found that he did not torque anything when he put in the new set of injectors. I am planning on putting in a new set of glow plugs and making sure everything is torqued properly. Just seeing if their may be something related to the noise to check while I am in there. Don't think I have a bad injector since the set was knew 2 1/2 years ago. Truck runs fine and has plenty of power, just has a knock.

 

Being you think you got all the air out of the system thur the fuel tank, which causes fuel knock maybe a bad o-ring. Had one guy on here that was going to change #8 with #2, and found the o-rings on #2 were bad. He did replaced o-rings and did put #2 with #8 and knock was gone. Never take anything for granite. Good luck,

Chet

 

Here is the knock I had before replacing two injectors - it only did this when really warm and in gear.

7.3L Injector Noise - YouTube