Hey ya'll this is my first post on this forum and I figured I'd give it a shot cause I'm lost on my truck. I'm 17 and I got a 96 ford 7.3 that I've been tinkering with since I was 14 when I first bought it. I bought it with a bad motor because the oil and coolant were mixed because either the oil cooler gave out or one of the head gaskets gave out. So what I ended up doing was pulling the motor and tearing it down to the bear block and had the block and heads machined and magniflexed. After that I brought it home and did a full rebuild with new pistons and rings and started putting it back together. It took me about a year to get it back in the truck and fired up from when I first got it. When I got it back in 2017, it had 306,000 orginal miles on it.

When it came time to put the injectors back in it though I wanted to save some money on them and rebuilt them myself. So I bought a rebuild kit on bitterroot diesel with the tool kit to tear them apart and rebuilt them. I also got the intensifier pistons that upgraded them from the stock 90cc single shot to 160cc with the stock nozzles. Then I installed all 8 of those with new o-rings and they worked great for a while... Then after I put about maybe 200 miles on the fresh rebuild I started running into some issues. Basically what ended up happening was it would shake pretty good when it was idling and I found out that I had a mis-fire on cylinder #5. So I started throwing parts at it and ended up replacing the valve cover harness twice on the passenger side head and changing the pig-tails on the valve cover harness wire. After I did that and cleared the codes it ran awesome again until I started driving it.

Then I did some research and decided to replace the #5 injector with a new one from Full Force Diesel and pulled the other 7 to put new o-rings on them. Before I did it though I swapped out the intensifier piston and a few other little things in the new one so it would make the #5 injector a 160cc injector. I also put a new injector cup in cylinder 5 because the current one in it looked a little gnarly. And for all I know that was probably the problem all along.

**I know I'm writing a **** ton but here's where I came to a stop because I don't know what to do next**

After I installed all 8 injectors with new seals and everything and cleared the cylinders it fired up after I got the system to prime. I also did a oil change too while I was at it so it took a lot longer to fire up because of all the air in the system. When it was running though I checked each injector to make sure each one was firing and the driver side head was firing perfectly but it wasn't the same story on the passenger side head. I had fixed the misfire issue on cylinder #5 and that one was working awesome but now injectors # 1,3, and 7 weren't firing.

So basically here's where I'm stuck at because I don't know if it mechanical or wiring anymore. If ya'll can think of anything I would appreciate if you said something cause I miss driving this thing. Thanks!

 

Sounds like a bad idm. If you’re certain all the valve cover harnesses including the UVCHs that’s where I would be next. Someone else will chime in with another idea I’m certain

 

Why would the HPO system have air after an oil change? Did you do a top end change as well?

You can buy a cable and hook up to FORScan to pull codes as well if you haven't already. If no codes you can look to the mechanical side of things. 9/10 people won't try to rebuild their own injectors though, not saying that's the issue but if no codes pop up I'd try swapping the bad injectors into the holes that aren't misfiring and see if the problem follows.

Sorry to hear you're having issues. I'm sure you'd rather be driving the damn thing at 17... Nothing picks up chicks more than a throaty 7.3

 

Oh no I haven't touched the Hpo system at all but when I pulled the injectors out air got into the oil rails and I had to build up pressure again to start it up. I've tried switching around injectors on the side that I'm having problems on and I kept coming back to cylinder #5 on the scanner.

I do got a question though... Are you able to run an idm out of a newer 7.3 like from 2000-2003?

And yeah man, I can't really pick up chicks in my little honda right now lol

 

From what I recall the newer IDMs are fine. They run at a higher voltage than the OBS which are actually better. If you spend some time on diesel tech Chattanoogas website they talk a bit about that.

If the problem keeps coming back to #5 I would suspect wiring....

 

Also in the future, pulling the icp and opposite side plug to fill with oil goes a long way with cranking when you pull injectors.

 

Well.... I finally figured out what was going on with my truck. For the longest time I had a mis-fire on #5 cylinder and tried a lot of different things. What had happened was the injector cup went bad and was allowing coolant to get by. So with a new cup it fixed the issue. While I was in there I decided to buy some new injectors for it, cause the injectors that were in it probably needed changing. I ended up going with the stage 1.5's from full force diesel and man let me tell ya, it woke her up A Lot. I also found that 2 of the prongs in my valve cover harness were bent down in each connector making 2 of my injectors not fire. With a new set of connectors she fired right up. Anyway just wanted to give y'all an update on what I did. Thanks for your help!