WE FIXED THE PROBLEM - AND NOW IT'S BACK!

I have an early 7.3L PSD with 150K miles.

At the suggestion of FAT Diesel, I had the shop replace the #8 AND #6 injectors (with used injectors) and it fixed the problem. It ran great for about 8 months, but started missing again. The miss got worse. It started belching white which was worse when cold, but didn't ever stop (even when hot).

As a result, I bit the bullet, and replaced ALL of the fuel injectors (rebuilt). When I pulled the #6 injector, it was totally black, and completedly plugged up! The #8 injector didn't look too good either.

After replacing the injectors, the is no longer belching white exhaust, but it is still MISSING. When it's cold, it runs really rough (loud rod knock). It misses from idle to about 2000 RPM where it still misses, but is less noticeable. Once it gets to normal operating temperature, it smoothes out, and runs pretty good. I live in Phoenix, so the temperature does not get too cold (low of 45 degrees).

I have driven the truck about 5000 miles since the injector change, with no improvement. I also recently replaced the injector harnesses but there was no improvement.

I am about to give up and take the truck to the stealership. I have been scouring the related posts regarding this problem and I think that it still could be the following:

1. IPR
2. IPC
3. HPOP
4. Wiring
5. Glow Plugs
6. Compression

Does anyone have any suggestions?

 

I didn't se EOT on your list.....

 

There is a 42 pin connector over the valve cover on the driver side that has the wires from the injectors to the IDm in it. The wires from the IDM are on the bottom of the bundle and have a tendency to get chaffed on the valve cover. check bot sides of the harness very closely. Another spot that is not real common is where the IDM leg of the harness comes through the inner fender behind the intake box it could get rubbed on a sharp edge and cause ehough of a cut to ground out and injector or two.

What was the injector plugged with? you did clean out the fuel system before putting in the new ones.

 

In spite of having 8 rebuilt injectors recently installed, it sounds like another bad injector to me.
That "rod knock" sound is a giveaway.

 

amiller93,

The #6 injector was previously plugged with what looked like carbon (like you would see on the top of a piston).


Kwik,

You may be right - I may still have a bad injector, but listen to my latest story:

After reviewing several posts on this forum, I decided to inspect the IPR for a loose nut. Guess what? The nut had fallen off and was on top of the engine. I installed the nut and torqued it to 56 in-lbs, and took the truck on a test drive. It was MUCH better - almost perfect - just a little knock. I was tickled to have it fixed, but when I started it the next morning, the miss was back, but not as bad, and the truck seemed to have much more power. It seems to get better and better the more that I drive it.

Here's the question - What does the IPR nut do? Does it regulate the injector pressure? Does this story make sense?

 

The nut holds the magnetic coil in place. There is a piston in the ipr that moves in and out to increase or decrease the oil in the inj. rails. When the nut comes off the coil will slide back on acceleraton and totaly throw the pressure out of whack. I had the nut come off on my truck. On hard acceleration the truck would fall on its face. So keep an eye on it!