I resealed and pop tested my injectors they all tested even but 550 psi low they were at 3000psi, I went ahead and stuck them back in since it ran fine before i pulled them and i had no way to adjust it. I put the 3800 spring in reindexed the throttle and i was able to turn the fuel screw all the way in, and now it has a knock to it, I'm wondering since i turned the fuel screw all the way in and the injectors are popping lower if it advanced injection timing enough to cause it to knock, I ran the truck for alittle while and then drained the oil and there wasn't any metal flakes and it happend after i messed with the screw and spring which leads me to to much advance. What are your thoughts? Should i retard the pump?

 

Since you didn't change the actual Pop-Pressures of the injectors, that's not it.

FYI: Pending what your intended use for the engine is, 500psig isn't necessarily a bad thing. On a hot-rod application, where a clean burn isn't top priority, dropping the Pop-Pressure is one way of getting a little more fuel in. It may not atomize the fuel as well as the same injector set to Pop at a higher pressure though.
In the overall scheme of things, altering the injector Pop-Pressure does alter the injection event timing relative to the crankshaft position albeit potentially minor.

If I'm not mistaken:
- A lower pop-pressure means a wider injection event window as there's a lower "Close" pressure as well. It's a wider window of potential fuel flow time wise.
- A higher pop-pressure means a narrower injection event window as the close-pressure is also higher.
The delivery-valves heavily influence the actual stopping of the fuel flow at the end of the injection event. So my mental math may be off there.

NOTE: The piston that moves the fuel is driven by the cam-plate. In my eyes it presents with a sine-wave. As such, the actual pressure presented may go up and then back down with the constant resistance to flow presented by the fuel delivery system (delivery-valves, plumbing, component internal passages, injector pop-pressure, etc).
I believe that in terms of achieving the cleanest burn is to have the pop-pressure set to open the flow close to or at the highest pump-pressure. That will have the highest working pressure to promote good fuel atomization at the nozzle. This will most likely result in a narrow injection event window of opportunity.
Wanting specifically more fuel out of the same nozzle over the above means reducing the pop-pressure (which again widens the window for the injection event) may also mean moving further out on both sides of the pump's cam-plate (positive pumping event relative to injection event timeline). This means the working fuel-flow pressure available at the nozzle as it opens won't be as high as that described above, and won't atomize the fuel as well. Hence, more of the typical Haze at idle for example.



I'm rambling.

If you didn't take all the injectors apart at the same time, and mixed-up all those little, tiny shims dividing them up evenly amongst all the injectors. , and simply disassembled, cleaned and then put back together . .. individually, you should be good to go there.

Is the engine still cold when you're hearing the knock? Does the knock only present at a given range of rpm? Does it knock all the time no matter what?

 

Only at idle? If so I wouldn't retard it.

 

Pull the power lead from the KSB and see if it still knocks.

 

Knocks mainly when warm.. I can start it let warm up a little then drive it a mile then when I stop, I can hear it a lot more. Mainly at an idle and I can kind of hear it at cruising speed, under load I don't hear it... I'll unplug the lab and try it. I'll post more/better info when I get to a computer.

 

Just so it's been asked, are you still running the original flex-plate with the automatic transmission? They're known to eventually crack around the center hub and initially present as a strange knock. It often sounds from the rear of the engine and is not so easily pointed to.

 

I believe so.. I hope that's it....ill just run it till it breaks and then pull the trans that way I know for sure lol.

 

I dunno . . . .

I'm not saying that's your problem. I'm just saying, as you look, feel, and listen to the engine, that can be one of many sources of strange knocks.


- You can individually loosen the injector feed lines while the engine runs, and see if you can locate the knock to a specific cylinder (if it's going to). Venting the fuel injection pressure like that will have the injector act like pulling the hot wire from a spark-plug. If the knock goes away with killing a particular cylinder, it can potentially point to a possible problem there.

- Is it frigging cold where you are now? Is the KSB being energized thus advancing the idle and above injection timing?

 

Make sure your injector lines are tight. At the injectors and at the pump. I noticed a loose one at my pump this weekend when retorquing my studs. I tightened it up and it smoothed out my motor a bit.

 

bc, i'll try that and see what happens its not real cold was in the 40s and 50s,

92smokin, I'm pretty sure all the lines are tight but i'll double check, I've never pulled the lines from the pump so it should only be at the injectors.

 

Well I loosed the lines and found the number 3 cyl. Doesn't have the fuel pressure the other 5 have....and the engine sound doesn't change like the others... What could be the problem?

 

What would cause low fuel pressure on the number 3 injector?. When I crack the line fuel dribbles out. Is the delivery valves what controls the pressure to the lines?

 

The delivery valve just prevents fuel from going back into the pump, and also damps pulses in the injector line. Peak pressure is controlled by the injector (pop pressure)

I would bet on a seriously messed up injector. There must be a pro on here that could opine if a bleeding leaky injector would cause a knock.

 

It's either the injector, or it's associated delivery-valve. (A single rotating piston pushes the fuel to each or the six injectors).

- I'd pull injector #3, take it apart looking for anything obvious, put it back together and reinstall it.
- I'd also go ahead and remove each delivery-valve, disassemble/clean/reassemble, and put them back in.
Both are very easy to work on. Nothing NASA like.

 

Just to narrow it down, pull injector #3 and swap it with an adjacent injector. Fire it up and see if the miss follows the suspect injector (be sure to let any air get out of the moved injectors before you condemn anything. Rev it a few times).