Need Help with 7.3 IDI Factory Turbo - Lots of Smoke and Idle Issues

I’ve been searching everywhere online, but I still haven’t found a solution. My 7.3 IDI is giving off a lot of white-blue smoke and has a bit of a ticking/stuttering sound when idling. It doesn’t stall or anything, but I can’t figure out what’s wrong. It doesn’t seem to burn oil and has the usual blow-by for an IDI. Coolant and oil both look clean.

I’m dealing with a bad thermostat and probably a couple of dead glow plugs, but I don’t think they’re causing this level of smoke. It takes around 8 seconds to crank, fires once, and then fully starts after a few more seconds. Once it’s warmed up, the smoke fades until it’s barely noticeable.

Hate to think it’s the rings, but I’m stumped here. Any ideas?

Sounds like you might have air in the fuel system. Could be causing the rough idle and the smoke.

Rafe said:
Sounds like you might have air in the fuel system. Could be causing the rough idle and the smoke.

Thanks, I’ll take a look at the fuel return lines and see if that helps. Hopefully it’s something simple.

@Greer
I’m not sure, but I think fuel return lines might not be enough to cause rough idling as bad as you’re describing. Here’s what I found in a 7.3 IDI turbo diagnostic sheet:

Injection Line and Nozzle Check

  1. Inspect injection lines for kinks or restrictions.
  2. Test each nozzle’s opening pressure and tip leakage.

Be careful though; the fuel spray from the nozzles is intense enough to cause injury. Make sure to handle them with caution!

That actually sounds a lot like my '90 when there’s air in the fuel system. I usually have to crack some injectors to bleed the air out before tightening them back up. I’d definitely check your fuel system too.

Definitely sounds like an injector issue to me. If it were me, I’d replace the return lines, swap out the injectors, and maybe even add an electric lift pump to keep fuel flowing better.

Uma said:
Definitely sounds like an injector issue to me. If it were me, I’d replace the return lines, swap out the injectors, and maybe even add an electric lift pump to keep fuel flowing better.

Thanks for the advice! I’ll check the lines. The injectors are actually pretty new, only about 7000km on them, so I was hoping they weren’t the issue, but I’ll give them another look just in case.

Air in the fuel system or maybe a bad injector sounds like what’s going on here.

I’ve had some similar smoke issues myself. Does your dipstick sit properly, and are there any holes in your exhaust pipes? White smoke often points to air in the fuel lines.

If you haven’t replaced those old fuel lines yet, do that first. The 40-year-old rubber ‘fuel olives’ tend to harden and let air in. Also, check around the fuel heater and Schrader valve.

With injectors that new, they’re probably not the main issue, though it’s not impossible. If it runs fine once warmed up, that’s a big sign of air intrusion. Air can sneak in from various spots:

  1. Broken pickup in the fuel tank can suck in air if fuel is low.
  2. Bad diaphragm on the mechanical lift pump might mess with fuel flow and could lead to diesel in the crankcase.
  3. O-rings on injector caps might need replacing.

You’ll know it’s fuel starvation if, after warm-up, you feel a power surge on acceleration. Try replacing the injector O-rings (they’re easy to find on Amazon). You can also try running some fuel treatment. Check your oil level to make sure it’s not high from fuel mixing in.

If needed, consider an electric lift pump. Some people swear by filling a new fuel filter with old-style ATF for cleaning. If your IP’s still working, it’s probably not the issue. I’d bet on it being a simple fix.

Blow-by isn’t exactly normal for an IDI. My NA and turbo IDIs have no blow-by at all, and they’re at 225k and 383k miles. You might have a serious issue somewhere. A compression test might help to pinpoint it, but I hope for your sake it’s just injectors.