Finally got around to testing, and then replacing the glow plugs.. 4 stuck.

@MJGenay I guess we should have mentioned that air can get in without liquid leaking out. Air is much thinner.

Another way to see if there is air in the fuel filter is to just pull the filter in the morning before starting or doing anything else. If it's half full of fuel then you've got a drain back issue, which is likely.

Deleting the return line from the filter housing to the #1 injector return cap was actually a factory TSB, BUT I recommend putting a check valve in that line instead. A real one. There's one inside the filter housing behind that fitting but getting a stand-alone check valve works better for longer. Like this:
1/4" check valve on Amazon
I would gut the old check valve and get something like that.

Just to make sure, did you check the IP inlet? Mine was leaking there a bit for the last few weeks and would get air intrusion like crazy during the first few minutes before the fuel warmed up. Made for harder starting but it would try to take off on me just pulling out of the driveway and down the street.

Lubricity is key for these pumps...I also would caution using straight Seafoam. But maybe I'm wrong. ATF works great.

Sorry for the lack of communication guys. I slept like crap last night and woke up grumpy and tired. After fiddling with things around the house and the truck a bit this morning and hating everything I decided to take a nap. Less grumpy.

Yesterday I replaced the filter (filled it with Seafoam for good or bad), had Lindsy crank while I bled the air out, and then took it for a drive. Seemed to do fine. After 5 seconds or so of bleeding it cleared up and the truck didn't rattle at all (I had already driven it that morning). Tried turning it on a few hours later to take the truck to a dinner party and it rattled like hell again, so the filter itself isn't the issue.

At any rate I did run the truck for a probably about 5 minutes this morning trying to run the air out of the lines so I could replace some lines with a clear line and start trying to narrow down this leak. Found out the 1/4 inch line I bought is too small, so I bought 5/16 and 3/8 to be safe and then came home and went to sleep.

I would do the filter experiment to see how much is in it but the truck has been sitting for 3 hours with a missing line from the injector to the fuel filter... so I'm guessing all kinds of stuff is going to be screwed up. On the off chance it doesn't matter I'll loosen the filter and check it anyways, then get to changing some of these lines with clear ones.

I went to O'reilly's this morning (our only auto parts shop within 40 minutes or so) and tried to pick some some O rings thinking maybe I would just replace all of them on all the return caps. They couldn't find them even though the website said they were in stock... So I'm going to order some so I have them, planning to go with those good ones Franklin mentioned. Should be cheaper than the dollar an o ring oreillys quoted... and better.

Next time I'm in town for parts (probably later today) I'll pick up what is needed to replace that check valve.

Regarding that fuel heater on top of the filter housing... it doesn't appear to be leaking but could always be allowing air in. Is there any way to check on that or do I just need to replace the o ring?

Hang in there, man. I know how you feel.
I try to keep reminding myself that I didn't buy this vehicle because I like to work on vehicles, but because it's a vehicle that I CAN work on if I need to.
I figure the other option is to drop $50k on a newer rig plus pay the dealer to maintain/fix it.

Brian, I'm with you. That was the same exact deal with me. I can afford this vehicle and I can work on it. Sometimes I'm just frustrated by just how much I have to work on it.

At any rate I pulled the line from the number one injector running back to the fuel filter and replaced it with a clear line, then turned the truck on... AND THE FUEL SEEMS TO BE FLOWING FROM THE FILTER TO THE INJECTOR VIA THE RETURN LINE??? The diagrams I'm seeing show that as incorrect. At least the air bubbles are moving from the filter towards the injector return cap. That has me stumped. To be clear the bubbles clear up rather quickly and the bubbles are just from it being a new line empty of fuel.

EDIT.. oh ****. Whats the chance this means one of the injectors on the passenger side is stuck open until it warms up and therefore it is just SUCKING all the fuel it possibly can into that side?

EDIT 2: the fuel filter was still FULL of fuel when I tried to check the level.

I'm going off this diagram...

MJGenay said:

At any rate I pulled the line from the number one injector running back to the fuel filter and replaced it with a clear line, then turned the truck on... AND THE FUEL SEEMS TO BE FLOWING FROM THE FILTER TO THE INJECTOR VIA THE RETURN LINE??? The diagrams I'm seeing show that as incorrect. At least the air bubbles are moving from the filter towards the injector return cap. That has me stumped. To be clear the bubbles clear up rather quickly and the bubbles are just from it being a new line empty of fuel.

Click to expand...

Once I did the hard line delete kit from Russ Repair on my 6.9 (deletes the hard line/olives seals/filter head return line to #1 injector) It fixed a whole mess of running issues such as rough idle/surging/stumbling/long cranking. That was where my issues were from air intrusion/leaking. Just a thought.

I am at least supposed to drop this off at my mechanic tomorrow morning... we'll see if that happens. He's supposed to replace the axle seals on the Dana 50. I went to replace ball joints, tie rods, etc, and noticed the seals were leaking. Figured it was pointless to pull it apart twice and I'm not confident in my ability to rebuild an axle.

I'm going to go buy a check valve at O'reilly and put it in that return line from #1 to the fuel filter in the hope that it might solve my issue. I'm embarrassed by how this truck sounds on a cold start.

I ran another clear line from the #2 injector to the IP and turned the truck on. That runs clear as well but the truck still rattles like hell. I am assuming, as the fuel filter stayed full of fuel while it was sitting, that my issue isn't coming from the tank. I still haven't run a line into a can of diesel that runs to the fuel pump, I filled up a can but can't figure out how to get the screen out so I can stick a fuel line into it lol.

As far as I can tell my last point to check would be in the back at the #8 injector, where the lines come together from both injector banks and head to the tank. Unfortunately if I want to replace that line with a clear line I need to remove my banks turbo and thinking about how hard it was to get those nuts started I'd rather not do that... not to mention I'd be dumping my exhaust into the engine bay...

Instead of running the return line at the back of the engine from the Passenger side to the Drivers side, why not run it from the 2nd Injector back from the front, to the same one on the drivers side.
Then you don`t have to fight getting it under the Turbo.
Haven`t heard of any one removing the Turbo to replace this line.

Here is a YT Video from "Dieseltechron" describing how to check for hard starts, fuel drain back, air into the system, checking GP`s etc....
Great guy that worked at a Ford dealership, and loved to help people with these old IDI`s and PS.
Sadly he was killed one morning in a car crash going to work.



Goat

MJGenay said:

Brian, I'm with you. That was the same exact deal with me. I can afford this vehicle and I can work on it. Sometimes I'm just frustrated by just how much I have to work on it.

At any rate I pulled the line from the number one injector running back to the fuel filter and replaced it with a clear line, then turned the truck on... AND THE FUEL SEEMS TO BE FLOWING FROM THE FILTER TO THE INJECTOR VIA THE RETURN LINE??? The diagrams I'm seeing show that as incorrect. At least the air bubbles are moving from the filter towards the injector return cap. That has me stumped. To be clear the bubbles clear up rather quickly and the bubbles are just from it being a new line empty of fuel.

EDIT.. oh ****. Whats the chance this means one of the injectors on the passenger side is stuck open until it warms up and therefore it is just SUCKING all the fuel it possibly can into that side?

EDIT 2: the fuel filter was still FULL of fuel when I tried to check the level.

Click to expand...

The fuel returns to the fuel tank via the line running from the rear of the engine to the tank. So it stands to reason the return line from the fuel filter would have fuel making it's way back to that line at the rear of the engine to tank, and the way the fuel gets to the rear of the engine is the fuel return system.

Someone in a previous post didn't want to start any controversy, there is no controversy on this, all the fuel on top of the engine except the hardlines to the injectors does return to the tank via the line at the back, and any leaks anywhere in the system will let air in to replace the fuel.

Old Goat said:

Instead of running the return line at the back of the engine from the Passenger side to the Drivers side, why not run it from the 2nd Injector back from the front, to the same one on the drivers side.
Then you don`t have to fight getting it under the Turbo.
Haven`t heard of any one removing the Turbo to replace this line.

Here is a YT Video from "Dieseltechron" describing how to check for hard starts, fuel drain back, air into the system, checking GP`s etc....
Great guy that worked at a Ford dealership, and loved to help people with these old IDI`s and PS.
Sadly he was killed one morning in a car crash going to work.

xc_hide_links_from_guests_guests_error_hide_media

Goat

Click to expand...

I actually watched that video this morning, but thank you. He seems like a really knowledgeable guy, I believe I heard of him once upon a time. The way Banks had me modify it (per instructions) the return line runs from Injector 7 (against firewall) on the passenger side around the front of the intake and then back, then it ties into a T kinda behind the engine but also near the #8 injector. The other parts of that T are the return from the drivers side injector bank and the line going back to the tank. It is stupid unaccessible and while I was putting it together I kept thinking last year I kept thinking "this is a really stupid design"... but I couldn't think of anything better.

That T is bolted onto the intake. Realistically I should probably remove it, cap the returns at the back of the engine, and put two T's on the return lines half way up the injector banks, tie both banks together, and then run one line around the side of the intake and back to the tanks. I think that might be what you are suggesting. Problem is removing the existing return to the tank back there is pretty much impossible without removing the turbo...

Speaking of stupid design, mounting the glow plug controller over the passenger valve cover is pretty dumb. I have to remove the bracket every time I want to fool with that last injector, glow plug, or any of the fuel return stuff back there.

franklin2 said:

The fuel returns to the fuel tank via the line running from the rear of the engine to the tank. So it stands to reason the return line from the fuel filter would have fuel making it's way back to that line at the rear of the engine to tank, and the way the fuel gets to the rear of the engine is the fuel return system.

Someone in a previous post didn't want to start any controversy, there is no controversy on this, all the fuel on top of the engine except the hardlines to the injectors does return to the tank via the line i the back, and any leaks anywhere in the system will let air in to replace the fuel.

Click to expand...

Yeah I'm coming to the conclusion that that diagram I posted earlier is probably incorrect at least partially. It seems it is working properly.

At this point I don't know what to do. I'm going to put everything back together (naturally O'reilly didn't carry a check valve...), probably drive the truck to the mechanics tomorrow so he can do the axle (and hopefully not drive me into bankruptcy). I figure I should have it back in a couple days whereupon my new o rings should be here... then I'm just going to take the whole return system apart... again... and replace all the o rings.

Yes, I'm frustrated. Yes, this truck is cheaper than a new truck. Yes, I can actually work on this truck (and usually enjoy it). Yes, this truck has taken hundreds of hours of my time this year (since purchased early January) and cost me unknown lost wages (more like I don't want to do the calculations and find out).

I sure don't want to get rid of this thing but every once in awhile I think maybe it wouldn't be the worst if I drove it off a cliff... God I'm frustrated.

I've dropped around 8k in parts into this damn truck this year. Yes, that includes the turbo and a new set of tires, but still I'm looking at north of 3 grand in odds and ends. Blows my mind.

Okay gentlemen, I calmed down a bit, then went through the roof when I added up all the parts to discover I've dropped about 10k in parts into this truck this year... I'm hoping my math is wrong but maybe thats why I'm almost broke. Working on calming back down again. Oh well, 15k total is still a hell of a lot cheaper than a new truck.

Anyways the truck ran rough as hell again this morning when I turned it on to take it to the mechanics for the front axle (kicking myself for that as it isn't really in the budget). I've discovered if I kick the RPM's up to about 1200-1500 the rattling goes away. Let off the pedal and it intermittently comes back, goes, comes back, goes... Sometimes the rattle won't stop unless I hit the pedal. After about 5 minutes or so of this crap it clears up. At least the glow plugs are figured out though, the truck starts up in a couple seconds every time now, it's great.

Here is my plan. I have new o rings coming in Wednesday, I'm going to replace all of the o rings on all of the return caps and see what that does for me. I'm also debating taking that fuel filter off and running some ATF through it; I'm wondering if I have a stiction issue with the injectors, or one of them. Any opinions on that? What ATF should I use? I have some Mercon LV sitting around I think.

It is completely possible that I do not understand how these injectors work, in fact it is likely, however, I'm wondering if I have an injector that sticks when it is cold. The two confusing parts are if I get on the throttle it seems to temporarily "unstick" it and while it is cold it is intermittent... off and on rattle.

I do not regularly run any kind of fuel additive in my tanks. I have some Hot Shots Secret and I did put a bit in the tanks this most recent fill up but it didn't seem to make any difference.

What I'm noticing is the roughness doesn't exactly seem to correlate with the amount of time the truck sits, more so it seems to correlate with the temperature of the truck - is it cold or warm... Or at least that is how it seems.

To be clear the PO replaced the injectors and IP with remanufactured ones about a year and a half ago.

Is it possible it has something to do with the cold timing advance wire that goes to the pump? They do make the engine rattle, though it doesn't seem to affect power any. It has a temp sensor on the engine that activates this feature on the pump and also activates the fast idle solenoid.

This is starting to not sound like a air problem. An air problem would cause problems that would clear up pretty quickly, not go on and on like yours seems to do.

Just to make sure, it doesn't do it after the first start of the day? I wonder what would happen if you unplugged that temp sensor?

franklin2 said:

Is it possible it has something to do with the cold timing advance wire that goes to the pump? They do make the engine rattle, though it doesn't seem to affect power any. It has a temp sensor on the engine that activates this feature on the pump and also activates the fast idle solenoid.

This is starting to not sound like a air problem. An air problem would cause problems that would clear up pretty quickly, not go on and on like yours seems to do.

Just to make sure, it doesn't do it after the first start of the day? I wonder what would happen if you unplugged that temp sensor?

Click to expand...

Thanks for the response. I lost my fast idle upon cold start while I was changing the glow plugs, as in it wasn't working after the fact but was before. I probably leaned on something or hit something while I was working on the engine. This issue was an issue before changing glow plugs however it does seem worse now.

It does do it after the first start of the day, but it depends. For example, a few minutes, 2-3 hours, and it usually is fine. If its 5-6 hrs it might do it a little bit but it isn't as loud. Longer and it is worse. That could easily mean that the longer it sits the more air in the system... or it could mean the engine is just colder.

Here's why I think it might not be a fuel drain back issue. This summer, we left a few times for a week at a time for family stuff. The rattle seemed to be the same whether the truck was started the day before or the week before.

Rattle is much worse now than it was over the summer.

Where would I find this cold timing advance? If its on the IP its very possible I leaned against it working on the engine. Maybe it could be a partially broken wire somewhere?

The sensor itself is way down deep into the engine behind the alternator. I am not sure which wire it is on the IP, the IP has two single wires, one comes from the keyswitch and makes it run, and the other one is the cold start advance.

I drove my 6.9 up a steep grade too my in laws, parked it for 6 hours in 25 degree weather and when I got back out to it (no block heat nothing just sitting) the radiator was still warm to the touch, the engine was warm, warm air out the vents and she fired right up with hardly any glow plugs and no cold engine rattle due to timing adjustment from the cold. These things stay warm for forever and a day when you leave them so it could be thermal.