Super smoky startup fixed!

[Poorman]

So I've been chasing this problem for several years, I've posted about it several times. Startup on my "86" f350 6.9 was smoky beyond bad, it was like a locomotive. I only use the truck for excursions into remote areas so I just kept putting up with it, it only did it once a day. It would start almost instantly and run a little rough and puck smoke for maybe a minute and then clean up and run great, like it had a couple dead cylinders. So I went over every aspect of the glow plugs, new solenoid, built a new harness, put it on push button, tried different plugs ect. Not to get off subject but one thing that I did when making my harness, I kept the wires going to the plugs individual enough (not bundled) so I could easily access them with a clamp style meter, that way I can check the plugs super easy. I bought a compression tester and was surprised that it was pretty good. (375-415). Because it sets a lot for months at a time I was told my fuel was gunking up and causing my injectors to stick until warm, I send them in for an inspection, they said they were gunked up. After getting the run around for 3 weeks I had them send them back and I bought a pop tester and cleaned and shimmed them myself. To my surprise they were not gunked at all, even under a magnifying glass I couldn't find a speck of anything, felt like I'd been lied to. To be clear this was NOT one of the company's often mentioned on this site. Valve seals were mentioned so I pulled those out, a couple were falling apart so it was time but didn't change a thing. So I thought maybe the IP, so I called Justin, first time to call him, told him my symptoms, he said it's not your IP you've got air intrusion, but I'd had air intrusion before and it was different, it would start then die and then crank for 30 seconds, my returns were 8 years old but I had just replaced them anyways when I had the injectors out. He said replace all lines from the tanks foreword, I did and problem solved!!! The only suspect I found was a wet connection below the bypassed water separator, about 18" below where the rubber hose met the steel line. I don't understand how that could cause so much smoke, but it did, Hope this post will help others, Thanks Justin, you'll be my new supplier!

 

[WrenchWhore]

So, i'm assuming when air intrusion is happening it's sending aerated fuel which can't fully "prime" the injectors or pump well enough to give a good spray but not enought to stall? This happens until the air has been mostly worked out?

 

[The_Josh_Bear]

Does it run better once warm, too? I'd think that kind of air intrusion would have running issues, not just start issues. So glad you got that problem licked! And you found out a lot of great info about the iron beast, too. New lines and hoses, good compression, push button GP's, etc. You're good to go for a looooong time now!

 

[Poorman]

WRENCHHORE, I think you're right, the air in the lines lower's pressures and then the injectors just don't pop right. I really don't understand how
a leak 8 feet away from the injectors can cause instant smoke and rough running, it's like the air finds its way through the line to the injectors or pump overnight, it's like magic.
JoshBear, no, it doesn't run better once warm, it's the same. Before with all the smoke it would run great after just a few minutes and a little warm up. Started this morning with temps in the 40s and again a perfect start so I'm positive the problem is gone, it's sooooo nice!!!!

 

[IDIBRONCO]

I really don't understand how
a leak 8 feet away from the injectors can cause instant smoke and rough running, it's like the air finds its way through the line to the injectors or pump overnight, it's like magic.
JoshBear, no, it doesn't run better once warm, it's the same. Before with all the smoke it would run great after just a few minutes and a little warm up.

This is easily explained. You had fuel drain back, not air intrusion. You had a fuel leak, but it wasn't bad enough to pull air into the fuel system while the engine was running, which is air intrusion. Then, after the engine was shut off overnight, fuel would SLOWLY leak out of that spot so the rest of the fuel from there to the engine would drain back toward the tank. It wouldn't all drain back because you could start the engine and it wouldn't die. Just enough would drain back to let a slight amount of air in there, probably from your return lines, to cause the smoke and rough running. It would then clear up after getting all of the air out of the system.
THIS is why it's SO important to understand the differences between air intrusion and fuel drain back. Unfortunately, most people don't seem to even know or care that there's a difference. To them, everything is air intrusion.

 

[Nero]

Counter arguement, air intrusion is air getting in where it shouldn't, whether its on the fuel supply side or return. Typically though you are right it is generally called that on the fuel supply side.

 

[IDIBRONCO]

What about when the engine's not running and the fuel drains back? Air is not intruding then.

 

[Cant Write]

@Poorman now that you fixed it, do you plan to use your rig in more populated areas......

 

[DaveBen]

As IDIBRONCO stated "the fuel drains back? Air is not intruding then." fuel will not drain back unless something can take its place (air). It will create a vacuum and the fuel will not drain away. I am not saying you are wrong. I just wanted to clear this up.

 

[Nero]

Something has to take up the void, and usually its air getting in.

 

[Poorman]

@Poorman now that you fixed it, do you plan to use your rig in more populated area

Only to pass thru on the way to a remote area. Leaving in about a week, 455 miles to elk camp, I take the back way, largest town is Burns Or. about three stop lights. It will be nice to have that option like when I took the wife to arches in Utah last year.

fuel will not drain back unless something can take its place

So maybe I had a pinhole up by the IP that let air come in as the fuel drained out the line down a little lower, or that leak caused enough vacuum that it sucked air in the same hole that fuel was leaking out, much like when when you dump a full coke bottle upside down. Problem is it would smoke/miss instantly, so the air must have been at least as close as the IP which would make me think there was a pinhole in that area, but that's all under pressure while running so I'd assume there would be a leak showing. Keep in mind the only wet spot/leak I found was 15 inches below the bypassed factory water separator so air would have to travel up to the old separator back down to the bottom, then cross under the engine and up to the lift pump and on up from there. My guess is that there was more than just that one problem (leak) there must have been a leak in the area of the hard line from the filter to the IP I replaced the olives there and they were old and hard, my best guess is one was acting like a one way valve, leak under vacuum (during shut down) but seal up under pressure while running. I can visualize that happening. But damn, now that I think about it I think I replaced the olives a few days before fixing the leaky line and it didn't help. AH, but I haven't replaced the two olives on the hardline coming into the filter, I was waiting for a new filter head and was going to do them then because they will be loose. Maybe one of those is acting as a one way valve? It's pretty close to the IP. I wish I could be like my wife, she always say's "I don't need to know how it works, I just want it to work" .