7.3 IDI NA White smoke and misfiring on cold start and under load

[AmboIDI]

I've read that the black holley pump puts out too much pressure and the IP only needs a 4-6psi lift pump not 9-14psi like the black holley puts out.
Can anyone else weigh in on the best electric lift pump for these?

As for advancing the IP I plan to do a static advance by loosening the IP from the gear housing and turning it about 1/16" (like you did) at a time to see if that has any effect. Any reason why this method would be better or worse than skipping a tooth on the timing gear? Seems simpler and lower consequence than trying to get that timing gear just right.

Good call on the pyro. I should have done that from the start and am planning to put one in asap.

 

[Christian9112]

black holley pump does output as much as you say, but if you run it at 9 volts or so it can run at 6psi no problem. I have a voltage PWM. I can raise the voltage AND the pressure as I please. No matter how cold or how clogged the filters are, i get 6 psi. Flow rate does decrease as the filter gets clooged tho. If I see 0psi at full throttle, I turn up the pump a little then turn it back down at idle.

xc_hide_links_from_guests_guests_error_hide_media

I have holley red pump which outputs 6psi stock and very loud. Black holley pump at 6 psi is surprisingly quiet.

Im pretty sure my IP is worn. I also have new injectors but old IP. Also Delphi injectors. Did you pop test the injectors? I had 1 that was leaking and stuck right out of the box. 1 bad injector can cause smoke. make sure none are stuck before you mess with the skipping a tooth. Thats a lot of advanced timing.

 

[AmboIDI]

I see didn't put it together that you had a pwm hooked up to that. Pretty neat to have that level of control over the fuel pressure in the electric application.

Regrettably I did not pop test the injectors as I was in a bit of a rush to get them in. Everywhere I read says its the way to go because as you said right out of the box they can be junk.

I found a pretty trustworthy guy in town who has a lot of experience with the 7.3. I'm getting him to replace and time the IP and do some other work including checking each injector in case one or more are junk.

I'll keep everyone updated on how it goes!

 

[IDIBRONCO]

If it was an exhaust valve guide, it would make the noise all of the time. The black smoke at higher elevations is normal and can only be remedied by installing a turbo. You're just getting too much fuel for the air that's available.

 

[Christian9112]

I removed the air filter last time I was in the mountains. It helped a little with the restriction

 

[IDIBRONCO]

I removed the air filter last time I was in the mountains. It helped a little with the restriction

If you do this for just a little while you'll be ok. That's if you make sure that your air cleaner is clean on the inside. Otherwise anything that's in there will most likely end up inside your engine.

 

[Oledirtypearl86]

Otherwise anything that's in there will most likely end

I don't know about every body but there has been times I'm pretty surprised in what's in my filter wish I had pics

 

[IDIBRONCO]

I don't know about every body but there has been times I'm pretty surprised in what's in my filter wish I had pics

Same here.

 

[Christian9112]

I only do it when I know there will be long up hills. it drops the egt from 1200 to 1100 (around there) at 50mph

 

[AmboIDI]

The shop I found to do the IP did have good experience with the 7.3 but could not source a decent priced Stanadyne DB2 or give me a decent rate on labour. So that went out the window.

I'm at lower elevation now and everything is definitely running better, but not great. Still some white/blue smoke and the occasional misfire.

I did a compression test today with 7 cylinders reading ~375 psi and 1 cylinder reading ~300psi.
Anybody have thoughts about the difference in compression between cylinders? Is this amount acceptable?

My thoughts are that if it was a burnt valve or bad exhaust valve guide the compression would be even lower. Also with what IDIBRONCO said if it was a valve guide I'd hear it all the time and I don't.

Thoughts?