Clear bleeder line installed and this is what I found

[NWDmax]

Installed a 1/8" npt nipple in place of bleeder valve on the Mega filter.Ran a 2 foot piece of clear 3/8" fuel hose and put the bleeder on the end.Installed a piece of clear 1/2" between the FICM(EDU) and the factory filter head.
I'm seeing almost no air going through the FICM to factory filter hose.
I am seeing a lot of BB sized bubbles coming out of the bleeder port on top of the Mega filter.A steady stream even at idle.I'm still seeing these bubbles even after shut down for probably 5 minutes.They just keep coming!
I'm thinking my problem may be a leaking gasket on the Mega filter.Tried to tighten more with a strap wrench and It wouldn't budge.
Next step going to remove and put the dielectic grease on the gasket and re install.
When I'm seeing the bubbles after shut down the FICM clear hose is full of fuel and remains that way.
Any other suggestions?
I think I'm getting close! :D

[hoot]

Where the heck is the air coming from? I wonder if added restriction is pulling it out of solution?

Either that or a local leak in the filter head. What else could it be?

[ 05-14-2003: Message edited by: hoot ]</p>

[NWDmax]

Hoot:I think its got to be coming from that location.
I tightened the hose clamps very tight and used pipe thread sealant in all the threaded connections.
I tried banging on the side of the filter when the engine is running and I get even larger bubbles.(btw I used my fist ha ha).
I'm thinking its got to be the filter gasket because of the volume of air that collects in my bleeder extension in such a short time.
Can't see how it could be the hose connections or nipples because I pipe doped those and they are very tight.

[56Nomad]

As I mentioned before, the ring gasket is round and the
assembly head is a flat surface. With the amount of vacuum in the
line I wonder if the air is "burping in" at this weak link?

Any thoughts.....?

[ 05-14-2003: Message edited by: 56Nomad ]</p>

[hoot]

You could put a very thin layer of grease on both sides of the gasket. I hate saying that cause i would not want any foriegn substance getting into the fuel stream.

Or.....

Clean it up and silicone the darn thing around the filter and let it dry good.

If the bubbles go away...... walla

I used teflon tape on all my fittings. I don't know if that's the right stuff but I have no problems. I was careful to keep the tape high on the fitting so I didn't get anything loose inside the filter head.

[ 05-14-2003: Message edited by: hoot ]</p>

[Kennedy]

Blake,

I am surprised/encouraged to learn that you have no bubbles from the EDU. I would suggest that you monitor this for a while though to be certain.

As for added restriction, the majority of what little restriction is added will be INSIDE the element of the Mega unit. The bleeder is on the outside of the element. It is absolutely possible that the gasket is leaking, OR (another can of worms) the element canister seam as well...

[Kennedy]

In light of the fact that we cannot seem to find any consistency in air volume or source of entry in these trucks, I'm getting a notion that my kit is over engineered, and is an EXCELLENT air seperator. That said, I see 4 possibilities:


1) Install a short nipple w/o a stem for the post seal OR clip/notch the post seal so that air will channel through the threads and pass through the system as it normally does.


2) Install an extension to get the suction point down to below the 1/2 way point. Apparently some Cummins engines had this issue with an externally sealed post and the solution was to add a deep suction stem to a point near the bottom of the element.


3) Install some form of lift pump.


4) Leave as is and bleed periodically, either manually or with an auto bleeder system as others have been experimenting with.


While I am opposed to allowing the air to pass as in #1, it most definitely occurs in the factory setup. The extension may only buy time between bleedings, but apparently has worked in the Cummins (different elements entirely) applications. The lift pump notion is taking things into your own hands...

[NWDmax]

JK:You have mail! smile.gif

[Buck]

The new CTD H.O. in the '03 Rams have a lift pump in the tank. They have a Bosch common Rail too. Just food for thought.... Uncle just bought one. Quieter than my Max.

[LanduytG]

To see if the Mega has a leak just disconnect everything and put a Mighty Vac on it. Pull 25" of vacuum and see if it drops. This is how I found the leak on the Cat filter I sell for the VW TDI. Nature hates a vacuum, if you have a leak you can find it with a vacuum easier than presure, at least small leaks.

Greg

[Dave Lewis]

Buck,
It would be interesting to know if the Rams have the low pressure pump on the engine also like the DMAX. If you can find out let us know.

[HoustonDMax]

JK, you left off 5. Find and seal the leak.

Got the short nipple, and will put it on this weekend. I want to first see if re-doing all the connections I messed with putting on the Mega changes anything. I know my filter can not go any tighter.

If I still have air, time to start with the clear line, and track it down. The short nipple should at least prevent my stalls.

Thanks!

[NWDmax]

I've got the Mityvac but how about a hint on the easy way to get those filter head hoses off the Mega filter.
May do the same to the stock filter as well.I know those pull off pretty easy.
Good idea Greg and thanks! :D

[Lone Eagle]

Greg, You might want to go easy with 25" of vacuum. You can very easily cause a leak. I doubt most filters are rated that low. I know vacuum system filters are not rated for positive pressure. Later! Lone Eagle ;)

[FirstDiesel]

JK

Will you be persuing additional fixes for the system to eliminate the air. I have air in my filter everytime I bleed it. So far it hasn't stopped the truck from running but I just don't have a warm fuzzy about it.

I do not have the skill or knowledge to produce something like an auto bleeder.

[jbplock]

Blake,

If you have the push-on hose barbs on you MegaFilter (the ones designed to seal with out a clamp), they can’t be pulled off (by design) with out slicing the hose. My Weatherhead catalog says to carefully make a parallel slice in the hose from slightly behind the fitting to just beyond the end of the internal barb - without hitting the barb - as this will damage the fitting. With the hose sliced, it should come off with a quick pull. However, this will obviously shorten the usable length of the hose when you reconnect it. So unless you have enough slack in the hose you will have to replace it. Another approach would be to first test vacuum between the hoses that connect the Megafilter between the OEM filter and the injection pump. This would check the complete Megafilter assy (minus the OE connections). I was thinking of doing this test if I experience a hard/no start after running a long time with out bleeding (I’m currently at about 300 miles since my last bleed and have yet to have a starting problem). I purchased some

[Manfred]

Drove my truck this W/E for about 600 miles with wife and relatives. I was required to lift the hood at least half a dozen times to pump the primer about 30 times, before I got the truck again going. The air lock developed in time intervals from 5 minutes on and up. In many cases I avoided shutting down the engine and left it idle, rather than do the primer trick. Once continuously running, no engine shut down.
This leaves me to believe, that the injection system can handle any normal outgassing in the vacuum induced fuel flow, as long as it isn't collected. I think that JK's thinking is correct, to alleviate the problem using suggestions 1 and 2, thus eliminating the dead space created in the present Mega Filterset-up.
Thanks to all members who have the means to participate to lick this problem. I follow the work on a daily basis.

[chuntag95]

Manfred,
Sounds like you have an extra amount of air getting in your lines. Do you have a Mega installed or some other filter? What have you tried to date to reduce your air? I saw a good drop in volume from greasing the QD by the firewall.
Chris

[NWDmax]

Chuntag:Looking at his sig looks like he has the Mega filter too.
I didn't catch it at first either! smile.gif

[Manfred]

Chuntag

I installed the post-OEM Mega filter without the use of any additional sealant, except for a layer of diesel oil applied to the seal. The filter can has been tightened harder than I normally do on smaller filters, due to the larger filter diameter. All connections on the filter head have been sealed with blue Loctite, which allows the removal of same in the future. Both hoses have hose clamps at the in-and out connectors.
I had no air problem before the Mega filter installation. The truck has just turned the 11K mark.

[chuntag95]

Manfred,
Any sealant on the bleeder screw threads? I used Permatex thread sealer on all of mine. It will come off, but not without some effort and a flare nut wrench on occation. It's strange that you are having the problem so often. Most who have had stall issues also had them before. Have you tried any vacuum tests?
Chris

[Kennedy]

Kinda waiting on Houston Dmax and the "snoutless" nipple install.

I have Abear running a small lift pump. From what I am told, the transfer side of the Bosch pump is a vane type pump, and there is no apparent "weakness" or area that would be built for vacuum and succumb to psi. We'll see how Tommy does. Initial findingsare that the lift pump when stalled (not running) will increase restriction by about 2"hg. This isn't really all that bad considering that there is a 1" difference from E to F on the tank level.


I'm really surprised by all the massive air qty issues. I forget where, but someone with a Cat filter had a similar issue. I don't remember if I bled min since the dyno run on the 10th or not. If I did, it was only once...

[hoot]

The Bosch pump uses a gear type first stage pump into a rotary piston high pressure pump.

[chuntag95]

Well, I have some strange data. Before I left work, I filled up my tube bleeder. By the time I got home, it was 39 inches down. The tube was collapsed, so I pumped it up and it reduced the volume to 19 inches. This mornings run was at 11.5 pumped up. It seems you can about cut your volume in half. Now, I would put a gauge on and try to get the pressure close to atmospheric pressure to do my measurement if I had a gauge. Hmmm, I wonder when someone will come out with an affordable gauge for this beast. JK? Are you listening here? HURRY UP!!!!! :D No pressure. tongue.gif (Okay, enough busting JK's chops, back to the story.) The difference between this morning and tonight was about 25 degrees F. The route was the same and the time was close as well. It appears that temperature is either allowing more gas to come out of solution or allowing leaks to show up. It also seemed like the vacuum on the system was higher since it was collapsing my hose. Thoughts? :confused:

[imported_]

JK,

I was, and still am having issues with air in the cat filter in the JK position. It has gotten better but it is still present. A slight hesisitation about 7 secs after starting a rested engine. I clamped the pushlock and tread sealed the bleeder plug yesterday. I will see if this helps.

I talked to the shop foreman at CAT and he suggested the primer plate may be the issue.

I am not convinced if this is a Duramax issue or an install issue or a filter design issue.

I am pumping the primer (10-15 pumps) about every 1500miles. Not a huge issue but still a PITA. And trying to explain to the dodge guy beside me when it happens is just down right shameful. redface.gif

[chuntag95]

This keeps getting stranger all the time. This morning's drive in was at 66 degrees. When I got in, the hose was half collapsed, but only about an inch of air was present. When I pumped up the system, the air was in the fitting and could not be seen. I guess I will se what tonight brings, but temperature might have more to do with it than we thought, showing outgassing to be the largest problem (in theory).

[Manfred]

Chris,
I did Loctite the bleeder connection to the aluminum block. As for affect of temperature, I drove from the Pacific Coast (sea level and temperatures in the 70's) over the mountains
(approx 6000 ft) to the desert, again low altitude, where temperatures were at 98deg F (in the shade) and back.
My thoughts are to keep the truck as standard as possible. Adding the fuel filter made sense to reduce wear and improve reliability, but we may be doing more damage to the HP fuel pumps by running them dry for short times if the prime has been lost. Adding a pump to make the filter work, is in my mind getting too far, and may not even address the root cause of the bubbles.I don't think that the main cause of the airlock problem is associated due to incorrect installations. It happened to too many members, even with other filters, but similar layouts.

For JK - Are we sure that the filter seal holds the vacuum? Someone on the DP questioned if there should perhaps be a recess for the filter gasket in the filter head? Has this been tested out?

There are only six connections where air could enter the system. All metal to metal connections (3) are sealed with Loctite. The hose connections are tight. The bleeder screw is tight. Based on the size of the filter, the largest lb/sqinch vacuum acting are on the filter seal. Is the mechanical surface pressure on a tightened seal adequate for the application?

[NWDmax]

Manfred:I vac tested both the Mega filter with hoses connected and the stock filter too.It held over 15 hg for two hours on both.
Going to leave work early to start replacing the quick disconnects.
I believe Abear and Chuntag saw a dramatic reduction in air when they did it.
Could be the vibrations when driving cause those QD's joints to lose there seal and allow the air in....
I see some air at idle but a lot after a very short drive.
I'm convinced that the problem for most of us is in those connections.

[jbplock]

Blake,

The QD's are definitely non-ideal and worth replacing but they may not be the main problem. I replaced the QD's at the tank with hose and clamps, but saw no difference gas accumulation. Even if it didn't make a significant difference, the hose and clamps make a more reliable connection. I'm no expert on this subject, but it seems like there is more going on here than external leaks, since so many of us are experiencing the same gas accumulation. Leaks will make things worse for sure, but it can't be the only issue. Tommy's pressure and vacuum test at the tank connection passed with flying colors but he still has some air. If I remember correctly, you saw bubbles in the clear line connected to your bleeder after shut down. Seems like this could be explained by out-gassing

[Dave Lewis]

Has anybody tried putting some fuel in a thick walled jar and pulling a vacuum on it to simulate what it sees in our trucks? Maybe we would see the bubbles form maybe we wouldn't. This might help eliminate one suspected cause of air in the system.

[chuntag95]

Dave, I have thought about that very experiment. I will have to see if I can rig up something tonight. The question is, how to perform the test and how to explain the results. Maybe what I need to do is fill up a bottle 3/4 of the way with fuel and squeeze the remaining air out. Leave it sitting and if air comes out of solution to releave the vacuum, we know our answer. That sould not take long and I have a bottle I think will work. What do you think?

[ 05-20-2003: Message edited by: chuntag95 (Chris) ]</p>

[a64pilot]

Dave,
Don't forget that we heat our fuel as well as agitate it.
BTW, the total "air" may only be 1 or 2 cc's per gallon or less as we continually recirculate,heat and agitate the fuel over and over again.

[ 05-20-2003: Message edited by: a64pilot ]</p>

[chuntag95]

a64, good point. I saw a differenct in the amount of air when the outside temp was higher as well. This test should address just outgassing without temperature change. I could devise a test to look at that as well. Hmmmmmm smile.gif

[britannic]

After the test, how about seeing what happens when the mega filter is connected to the jar and repeating the experiment?

[chuntag95]

britannic,
What do you have in mind? I am not clear as to what you are looking for and trying to test. :confused:

[britannic]

chuntag95: I was thinking if the results of the first test were unclear or showed no air release, then set up a test circuit that connected the mega filter to the jar and see if air came out of suspension when fuel was circulated between the two. It would require some form of pump to pull the fuel through the filter though. This would prove whether or not the mega filter was removing air as some have postulated.

[ 05-20-2003: Message edited by: britannic ]</p>

[Dave Lewis]

a64pilot,
Good point. How much of a temperature rise does the fuel have when it returns to the tank? I think JK ran the sending unit in a bucket of fuel. I wonder if a modification of our sending units like they have been doing on the PS would make any difference on the amount of gas that builds up in the filters.

[HoustonDMax]

JK, I installed short nipple over the weekend. Don't have enough time on it to say if it has eliminated my stalling issue. Need another couple of days on that.

Had installed 4 feet of thick wall clear 3/8" vinyl tubing to Mega bleeder port prior to nipple change, and clear vinyl tube from EDU to oem filter. Never sucked either tube closed, as Chris did, but had no problem filling the bleeder hose with air either. Finally cam to the conclusion after a couple of days that I had a leak somewhere in this bleeder setup (I had to angle over with a couple of 90's and install a couple of hose barbs), as with no movement while idling, no air. If I shook hose, large bubbles of air. About the only air I saw in the line from the EDU to the OEM was large gulps when I hit the primer. Didn't really see many small bubbles, though I saw a few.

By the time I concluded I had a leak in my bleeder trap, I needed to move on and intall JK's short nipple. I only want to check one thing at a time, so I put JK's beeder fitting back on at the same time that I changed the nipple. Getting the filter off was tough; strap wrench at the top, with a breaker bar. I don't think it was leaking. Just in case, I removed seal and greased both sides before putting back on. I also tightened the quicklocks as well.

I bought clear lines and material to install traps on the lines between the EDU and the OEM, the OEM and the Mega and the Mega and the engine. Once I reach a conclusion on the short nipple, I will go back to figuring out where the air is coming from.

I have not looked at any of the QD's, as my local parts houses had no QD tools (in a city like Houston, go figure). Had them order a tool, which I should get today.

Will post back with further results.

JK, is yur Mega line 7/16" or 1/2"?

By the way, I have not seen the increase in mileage that others have seen after installing a second filter. I wonder if excessive air could be the reason?

[Manfred]

I'm not sure if I'm full of hops on this, but I happen to know how grappa is made. In the destillation process you have basically three phases. The fore run, where the light volatile aetheric oils vaporize, at the lowest temperature, then the middle run and at the highest temperature the after- or end run, which contains the heavy fusel oils.

Have we built a still and all we need is a condenser? The "air" we talk about may be the good stuff, belonging into a snifter?

[chuntag95]

Hey Manfred, it only LOOKs like Mountain Dew. ;) It might taste like Grappa, but I don't think I would drink it. tongue.gif Maybe Chinturbe, I had that in Italy once and it was like drinking lighter fluid. I slept well though.

Britannic, I get it now. Build a small closed loop system with agitation, pressure variation etc. A little model of our system that you can see and watch. Hmmmmm, how would I model the tank? I remember some stuff I used back in chemistry class that would work great. Wonder what I can dig up.

Houston, hang in there, you got it on the run. :D

My lunch trip netted 5 inches of pumped up air with a 15" start and a flat hose. The strange part was I had pumped up the system before I went into the building. When I went out, I checked it and it was flat again. The engine had not run or anything, so what caused the vacuum, cooling? :confused:

I think JK's hose is 7/16 considering the trouble I had getting it on a 1/2 barb.

Modify On! :D

[Kennedy]

The hose is 1/2" or -8 but the push lock fittings are oversized to give good stretch/seal.

[jbplock]

Manfred,

I have also been thinking that the "gas" (at least some of it) might be fuel vapor. The last time I bled the megafilter with my pump-bleeder contraption, the first thing to emerge from hose before the fuel started flowing was a wisp of what looked like smoke or steam (??). :confused:

[chuntag95]

Okay, I pulled about 15 ounces of fuel out of my Mega last night and put it into a Stanadyne bottle. I squeezed it so the air was out and recapped it. I took before and after pictures and am now in the hurry up and wait mode. I was running late this morning, so I didn't get a chance to check it and see if I had any air yet. redface.gif I'll let you know.
Chris

[a64pilot]

I've been hesitant to really weigh in on this too heavily as I don't have a dog in this fight so to speak. I believe that some of you guy's seem to be building a nuclear powered wrist watch. While this may be entertaining to some, I really love figuring out exactly why some things happen, that's what I do for a living. It may be frustrating to others who may not understand that the motivating factor may be fun and a hobby to others. The way I see it is there are two ways to deal with the "air" that seems to naturally occur in the system.
1. Allow it to pass through as it apparently does in the stock system. Guy's with the Mega should be able to cut off the nipple or simply drill a hole in it.
2. Pressurize the system and prevent any air from forming in the first place.
Either should be a realtively easy fix.
I apoligize if I have offended anyone. I personally believe the experiments should continue, some are really having a lot of fun and learning alot and educating the rest of us.
It's just important I believe to bring up that several succesful installations of fuel filters have been performed with apparently no ill effects. It may not be necessary to replace or modify your entire fuel system or build nuclear powered wrist watches if your goal is simply clean fuel.

[NWDmax]

A64:I concur sir!
Well I pulled the QD off the feed line in front of the fuel tank and vac tested from that point to the FICM.It held at 15" for 90 minutes with nary a leak.Installed clear tube back at the feed line replacing the QD there.Purged system by pumping/bleeding and driving.The clear line at the tank shows only an occassional very small bubble nothing like what I'm seeing at the clear line I've installed at the Mega bleed port.I'll drive it today and see if the air I'm now seeing is just "leftovers" from having it apart.

smile.gif

[Bulldogger]

I totaly agree with A64. To those of you on the experiment hwy. have fun and enjoy. To people who just want to clean the fuel and protect the injectors like me, just let me know if my simple suggestion of cutting a hole in the side or shortening the nipple will work. JK? JK?.If air is normally in the diesel solution and out-gassing is normal there will always be air present. There-fore I want the simplist solution so I don't have to lift my hood every three hundred miles and bleed the Mega.John send me a nipple with a hole in the side your guess on the diameter, and I'll swap it for mine after I log several hundred miles and check the air situation. I prefer this to the shorter nipple as I want to limit any possible larger gulps of air. Dave :D :D

[Dave Lewis]

Chris,
Any results from the fuel in bottle test?

[chuntag95]

Dave,
I had one tiny bubble this morning. I wonder if I don't have enough vacuum on it. I also wonder about the heat factor. I thought about stealing the wife's hair dryer and warming it up to see if that makes a difference. I'll let you know.
Chris

[ 05-22-2003: Message edited by: chuntag95 (Chris) ]</p>

[Dave Lewis]

Thanks.
I'm going to do some experimenting this weekend if I finish my honeydo list. Hopefully with the extra day I can get to it.

[chuntag95]

Are you going to try and do the system model?

[Dave Lewis]

No, it won't be that sophisticated. I want to get some fuel in a jar and pull about 5" of vacuum on it and see the results. I will also try heating it up and see what happens. Somebody in one of the threads had a good point that after the engine shuts down the fuel is just sitting there soaking in all of the heat. I wonder if that is where the majority of gas is originating?

[chuntag95]

That was my point with the hair dryer. The second thing would be to shake it a little, while under vacuum to help it release the air/vapor. I have a really cool way to do this, but I might get a divorce if I use the wife's vacuum sealer for this. :eek:

[Dave Lewis]

Well I guess what she doesn't know won't hurt her right?? :rolleyes:

[chuntag95]

Knowing my luck I would suck diesel fuel through the entire thing and catch it on fire. :eek:
I have a hand vacuum pump I can use, but it's hard not to use a cool toy when you have it. ;)

[chuntag95]

Quick update. I put the dryer to my bottle and it started creating air. I posted pictures at http://community.webshots.com/user/chuntag95

[NWDmax]

Chuntag95: You got air by heating the bottle with a blow dryer so......
I'm thinking since the fuel is used to cool the FICM that its getting hot enough to cause some of the air we are seeing.
With all the testing I've done to date I still have not seen enough air moving through the lines to explain the amount I get in a 5 mile drive.

[NWDmax]

After driving and bleeding nothing has changed the amount of air I'm seeing in the bleeder.
My supposed vac leak does not exist.Kinda sucks since I thought I had it nailed.
Oh well I guess its short nipple long nipple or lift pump time......
:D :D
I enjoy the challenge!
Cheers!!
Blake

[HoustonDMax]

Short nipple update. Getting close to 200 miles on install, which was by the far the longest I had gone without a start/stall issue with JK's normal length nipple; no stalls so far. Will probably put a hundred miles on today. If still no stalls, which I expect to be the case, I will then conclude that my air problem has been masked.

Will try to post back this evening.

[Dave Lewis]

Chris,
Pretty interesting. Now just think of the fuel lines running over the engine through the filter and FICM back over the engine and into the pumps. Lot of time to get warm.. Did everybody see more air when it was warm outside (warmer fuel from tank) then when it was cold??

[a bear]

Dave,
Definitly. The weather warmed up quick here in the south and there was a noticable difference.

[Dave Lewis]

Now the question is-- how warm did you get the fuel Chris to cause this? Then how warm is the fuel when it goes into the pump? Of course with the lift pump this may not even be an issue.

[chuntag95]

DANG! I knew I forgot something! I meant to shoot the bottle before and after with my laser temp reader thingy. I didn't heat it very much. It was warm, but not so much that you couldn't hold onto it without discomfort. If my predator is correct, the fuel in our system is getting to that point and you have all of the aggitation (sp) of up, around, fitting edges, cavities, etc. All of those "features" are points to cause air to release.

I think Tommy and JK have the best solution to date with the regulated lift pump. You keep the air in solution to the injector pump. Once it's through the pump and at 23K PSI, it's not coming out until on the other side of the injector. The question that is left: "Is this a problem long term?" I still cannot answer that. My gut feeling is the particles are bad for the injectors and the air is bad for the pump. The air on the cylinder side of the injector could be detonating, but it is the cylinder side that runs a 17.5:1 compression ratio anyway. Maybe the peformance injectors will be better by the time I am out of my 100K so I don't have to replace with the $600 each stockers. Since they are changing the design (which says oops we goofed to me) the cost is not likely to come down with only 3 year models containing these. :(

[britannic]

Additional thoughts: I had an opportunity to see what happens to diesel when it gets too hot the other day, when my top radiator hose burst on the freeway (on my 6.2L); I shutdown as fast as I could, but the temperature still went off the scale as the heads heated up without coolant. Restarting after repair was just like an airlocked system - I figured the excess heating of the injectors may have liberated some air. There was no apparent damage once air bled out and the engine's running great.

Another thought, is that deep sea divers breathing tri-mix have to decompress in stages to prevent nitrogen from outgassing too quickly in the blood. Most liquids have the ability to dissolve/suspend air/gas under pressure, so the outgassing Chunta saw in the test is normal. Just boil a pan of water to see dissolved air bubble out of suspension. Chunta's experiment has shown clearly that even without the megafilter, air will come out of suspension in warm fuel under vacuum.

IMHO the high pressures in the common rail system should ensure that the air is suspended in the liquid until the pressure drops after injection - it might even assist combustion slightly (probably unmeasurable though).

So providing there isn't any air entering through leaky fittings/hoses and the engine is running without problems, we don't have anything to worry about.

[HoustonDMax]

Latest on short nipple JK sent me to try out. Had a start stall at 175 miles. Right in line with standardnipple. Seem like it ran for a few seconds longer than it did when it stalled with the standard nipple. Took 40+ primer pumps before I had liquid coming out the mega bleeder. Had visible vapor prior to liquid.

So much for the theory that air was being trapped above the bottom of the standard length nipple.

With the short nipple, I don't understand where I could have trapped enough air to need 40+ primer pumps to clear. With standard length nipple, it only took around 50 pumps to clear.

JK (or anyone else), any ideas?

Well, I guess back to the air traps and tracking down the source. I sure would have liked to have been able to not worry about stalls while I tracked down the leak.

[NWDmax]

Too bad Houston,I feel your pain.You think you got it licked and still no diff.
I'm probably going with the lift pump solution unless a miracle cure is found in the next few days.
I'll be happier knowing the air is reduced/eliminated and trapped than running it through the fuel system. smile.gif