Great input guys... thanks. Let me respond to several things.

My sig is not up to date. We did the in tank mods this summer, so the pickup system is all "cleaned up". I'll have to check the small inline filter ahead of the pump to see if it might be plugged.

Nick... thanks for the reminder about running w/o the VC's in place. Sounds like I don't need to do that and won't waste my time making the unnecessary mess.

Stewart... so kind of you to offer the pump. Having two more 7.3's at the house right now, though, I've already got a "spare" that I can temporarily pull off my F250 to check the pump itself (assuming that the inline filter is not plugged). If I didn't already have the "spares" here, I would certainly take you up on the offer. Regardless, I'm very grateful for your generosity.

I don't have a spare fuel pressure gauge that I can use, but I could always pull the one off my F250 for a temporary check, but I'm hesitant to start pulling everything off my F250. I'll try the pump first because that's an easy removal and swap out. If that does the trick, then I'll have the answer and fire off an order to Clay for a new pump immediately. However, my gauge has a short hose and is only visible under the hood... I do not have one where I can see the pressure while driving, so I can only check while in the driveway. I guess I could use the one I have in combination with the consecutive tromping on the accelerator to see if the pressure drops during the white smoke episodes. I'll keep that in mind if I get that far before finding the problem.

The reason I'm wanting to go under the valve covers is because of the AE results indicating that cylinder 8 has a balance fault from the cylinder contribution test.

One more piece of recent history that I have not mentioned is that one of my sons pumped in about 25 gallons of gasoline into the tank several months ago. I did not mention it because at the time, we only moved the vehicle about 200 yards, pumped the tank empty, refilled with diesel (took about 41 gallons), triple dosed the tank with some of my best fuel additive treatment, and we NEVER saw the first hiccup. Since then, we've run at least 2-3 tanks of diesel through the system, again with NO hiccups at all. I honestly believe it has nothing to do with what's going on now, but there is a nagging thought developing in my mind that perhaps I ended up with the some gunk from the gas/diesel/additive mixture which may be now plugging the inline filter ahead of the pump.

I'm also going to get rid of the small inline filter and switch to the larger Baldwin setup like I have on my truck. I just do not like the small filter surface area of the inline element, and I take comfort in how the much larger Baldwin setup gives me a whole lot more filter surface area to minimize pluggage potential. Regardless, that change will not happen today because I cannot get the new components until after the holidays.

So... today, I'll be doing the following:
1. remove the inline filter to see if that makes a difference in the sound of the pump on start-up...
2. if No.1 gives no improvement, open and double-check the filter in the valley on the engine, and change if it appears to be plugged...
3. if Nos.1 and 2 give no improvement, swap pumps from my truck...
4. if Nos.1, 2, and 3 give no improvement, I'll pull the pressure gauge off my truck and check pressure directly...

I expect that 1-3 above should resolve the fuel supply issue.

Then, I'll pull the VC's and check the harness wiring, install the 50-cent mod, and tighten (if necessary) the injectors and rocker arms just because I'll be there and it's a good thing to do.

Since today is Thanksgiving and we have company for the holidays, I may not get 100% of everything done until tomorrow, but I'll post back later today with what I discover.

GROUP HUG TIME...

Guys... my family has been asking me about what kind of input I've received from you all, and they continue to be so impressed with how helpful and generous you are. We (speaking for my entire family) are deeply grateful. I'll keep you posted.

Oh... and I hope EACH of you has a wonderful Thanksgiving. Be safe!!

 

I'd agree with everybody that said it was a fuel delivery problem.

Your course of action is sound, and I'm going to guess pre-pump filter.

Remember also, the pump inlet gets clogged sometimes. Ask Kwik.

Have you drilled out or eliminated the "check valves" sometime in the past?

Happy Thanksgiving to you and your entire family, Pete. You have much for which to be thankful!

Pop

 

When I was checking a pressure drop at WOT, I saw 5-10 psi increase in fuel pressure at the bowl when changing out my spin-on prepump filter. I would always start there when seeing a pressure drop, since it is the "first line of defense" after the tank.

 

Thanks, Marv. I hope your Thanksgiving is equally good. To answer your question, though, no, I have not drilled out the check valves, so they are a potential collection point for anything passing through the pre-pump filter.

Anyway... it is FIXED!!!

Just like several of you suggested, the problem was limited to a restricted fuel delivery to the engine as a result of a mostly clogged pre-pump filter. We were able to clean out the filter screen, and the engine is now running beautifully. While cycling the pump to remove air before starting the engine, I even had to ask Benjamin if the pump was running because it was so quiet. Hopefully, the fuel starvation has not caused any permanent damage to the pump internals.

I included a blurry photo of the crud we found so you can see it yourself (sorry for the pic quality, but it was the best we could manage in a quick moment).

We checked the filter again after our trial run through the neighborhood, and there is a tiny bit of junk in the glass sleeve again, so I'll have to keep my eye on it until I can get the much larger Baldwin setup installed.

I have not yet confirmed it, but I suspect the #8 cylinder contribution balance fault was due to reduced fuel delivery pressure/flow, especially with it being on the dead end of the head and I have not yet done the fuel crossover plumbing. I'll check that tomorrow, and if it verifies OK, I'm not even going to chase down anything under the valve covers until a later (non-holiday) date.

Thanks again for all your input. You guys are all definitely a very real part of the long list of things for which I am extremely grateful.

Happy Thanksgiving. Stay safe and enjoy your friends and family!!

 

I LOVE the easy ones!

Pop

 

Well....
I missed another opportunity to say check your fuel pressure, LOL.
Glad you got it fixed so quickly.

 

It was easy, but it has been sitting in the driveway for the last 5-6 weeks because I thought it was the tranny and I had so many other things going on (numerous out-of-town trips, three bedrooms worth of tongue-and-groove hardwood floor installation, new water pump in my truck, blown out spark plug in my son's 323i, Benjamin's temporarily disabled F250 after his collision with a BMW, new battery for my daughter's I35, etc.).

Given how easy it was, I almost feel bad about having taken so long to get it properly diagnosed and resolved. At the same time, though, I've had plenty going on and we are fortunate to have enough vehicles to have been able to get by without it in the short term.

 

glad it was $10 fix not a trans.