It may not be a leaking injector but maybe a bad spray pattern (dirty injector) so it isn't atomizing and burning properly at start.

 

That crossed my mind to. No real way to check for dirty injectors though is there? Any recommendation on injector cleaner or should I take it somewhere and have it done?

 

I agree with Jim on this. Fuel Pres Regulator is notorious for hard starting and black smoke when it does start.

 

You can try injector cleaner to see if it helps. Red Line Si-1 and Gumout Regane are the better over the counter cleaners. Most all other cleaners are just kerosene and do not much good. Chevron Concentrate used to be good too but they changed their formula a while back so it may not be as effective. Red Line and Regane have a stout cleaning agent called Polyetheramine or PEA. Regane High Mileage formula has the highest concentration of PEA but Red Line is near the same and both are very good. Red Line is hard to find in a store. Pep Boys used to sell Red Line but I do not know if they still carry it now. O'Reilley may sell it too or maybe order from Amazon. I know you can buy Regane HM at Walmart and probably most parts stores. It would be very good to first try an induction fuel cleaning service like BG or Ever Wear. You can get those done at most any good garage or tire store. The best method is to clean out the system with a professional cleaning first then keep your injectors and fuel system clean with a good PEA based cleaner every 3,000 miles to 5,000 miles after that. As Dan pointed out you could have a bad injector too and a fuel service could possibly clean it up. Don't rule out an injector but at 150,000 miles you could also be due for a new fuel pump, especially if you still have the original pump. The check valve in the fuel pressure regulator is known to fail around 125,000 miles.

Jimmy

 

So I pulled the injectors and found that cylinder 8 injector was leaking. Pulled the plug on it, and it was wet. I replaced the injector and put a new set of plugs in since I was already there and the old ones looked shot. I also put new o-rings on the bottoms of the injectors before I put them back in.

Truck fired right up, but now is running really rough. It's stumbling on itself, and wants to die at idle. Of course its not throwing any codes, but the live data shows it is running super rich....like - 33%. Where do I go from here? How do I determine what's gone wrong?

 

I am no expert by any means and am not real familiar with a 4.7 either but I still think you have low fuel pressure. If you can keep the engine running now with the new injector installed, what is the fuel pressure? If the book specs 49 +/- 5 and you were at 49 before replacing the injector, I think you are on the way low side of normal. I know on my 3.9 the book calls for 47 to 51 and it is always right at 50 at idle. I remember that from last summer when I was checking fuel pressure last when I had a bad Crankshaft Position Sensor. It would seem to me you are running so rich because the fuel pump is not delivering the right pressure and the PCM is trying to compensate by dumping more fuel into the air-fuel mix. I am no expert on a 4.7 but I would think that the fuel system characteristics would be similar to my 3.9.

Jimmy

 

LTFT at -14 could also be a symptom of low fuel pressure. Whatever the problem is, the PCM still sees the engine starving for fuel but no matter how the PCM tries to correct the problem the engine still runs rough or not at all.

Jimmy

 

It's a negative 33% (-33%). The truck is getting too much fuel and is trying to cut back on the fuel.

 

Well I am no expert and was wrong about that, sorry for that. Whatever the problem is I hope you get it fixed cheap and without too much trouble.

Jimmy

 

Swapped the old leaky injector back in and everything seemed to return back to normal. I'm guessing they gave me a bad injector. I know better than to buy BWD products. I think I will pick one up from the dealer and see what happens