UPDATE 2/17: Shepherd Engine Saga Continues - third drive - about the same

[Sean]

... For the fuel, I will look the SilverLeaf again, but I think it had some fairly high flow rates on the first test suggesting that restriction is not a problem.
...

Jim, FWIW, when I had the fuel restriction problem leading to low boost, the flow rates on the Silverleaf did not look abnormal.

Ditto for when I had a low power problem after the second rebuild, which turned out to be a restriction in the return orifice.

-Sean
http://OurOdyssey.BlogSpot.com

[rv_safetyman]

Sean, thanks for the input.  I can't recall how you determined that you had an issue.  I have "new" (from first installation) DOT tubing most of the way into the engine compartment and then Aeroquip AQP (I think - stainless braid anyway) to the Fuel Pro 382 filter.  From there I have more Aeroquip hose to the pump. 

I will look at the hose, but you can't always tell by looking at the outside.  I have a friend who can flow test the hoses on a test bench if I need to.  I did hook up an electric pump from the main tank (lost prime - clue?) and I think it flowed pretty well.  May have to try that again.  I also have an auxiliary tank for the Aqua Hot and generator.  It is plumbed to the Fuel Pro with ball valves.  I had thought about taking a quick run with the electric pump from that tank to the fuel filter.  Have to be careful as the return is to the main tank.

It looks like we may have a weather window on Wednesday for some more testing.  I need to make a checklist of everything I need to look at and do - thanks to everyone here

Jim

[rv_safetyman]

As long as we are listing all of things that could cause the low boost/power, I had an email from Brian Diehl on another subject and he suggested that I check my throttle to make sure it is asking for full power.  Indeed, the symptom really fits that issue.  I just went out and hooked up the Pro-Link and it is indeed going from zero to 100%.  Boy, I wish that was the problem.

I also looked at the fuel lines and could not see any problems.   Sean mentioned the return line.  I did have to do some re-plumbing, but it all looks OK.  During the next test session, one of the things I have on my list is to undo the return line, put it in a bucket and start the engine to make sure I am getting flow.

Keep up the ideas.  I will do some more testing on Wednesday and see if we can find the problem.

[Busted Knuckle]

Jim,
Undoing the return line is fine, but at the same time there is a restricted fitting coming out of the back of the head on the return line. It's job is to keep the fuel pressure up to the desired amount! So make sure that it still has that fitting is still there and restricted and not completely plugged.
FWIW   BK    (the politically incorrect busnut! ) 

[Sean]

...  I can't recall how you determined that you had an issue. ...

Jesus told me.

Actually, the fuel line restriction was a best guess; in reviewing my notes on the blog, here:

http://ourodyssey.blogspot.com/2005/05/were-free-were-free-free-at-last-from.html

... I see that we actually made several changes at once.  However, changing the fuel line was the suggestion of one of Pedco's top engine techs (whose name really is Jesus), who really felt strongly that this was the root cause.  Now five years later it is hard for me to remember exactly what parameters Jesus was looking at to cause him to come up with that diagnosis.

That being said, I think it was you yourself who had suggested this as a possibility while we were going through this pain.  It must be so, since I found it in the narrative from the whole episode that I started back then on "the other board."  Possibly worth a re-read:

http://www.busnut.com/bbs/messages/233/10261.html

I have "new" (from first installation) DOT tubing most of the way into the engine compartment and then Aeroquip AQP (I think - stainless braid anyway) to the Fuel Pro 382 filter.  From there I have more Aeroquip hose to the pump.

I will look at the hose, but you can't always tell by looking at the outside. ...

Right; when we  got the old hose out, it looked fine on the outside, but we could feel soft spots that could have been crimps in the inner braid, or perhaps spots where the hose was collapsing under vacuum.

Anyway, hope this is of some help...

-Sean
http://OurOdyssey.BlogSpot.com

[luvrbus]

Bet every thing will be ok when Jim gets the turbo back Friday that came from that engine and installs it


good luck

[niles500]

Sean - Jesus = divine intervention - LOL

[JackConrad]

Jim,
  Years ago when we first got our bus, We lost power on our way to a Bluegrass festival to the point we could not run above 800-900 RPM. WE changed the fuel filters, after waiting a couple hours for a friend to arrive with the new filters. New filters installed and away we went, for about 3-4 miles, then same symptoms. The friend said he had recently had a problem with a collapsed fuel line.  We ran a hose from the tank fill opening to the primary filter inlet, primed it and taped the hose to the side of the bus.  Bus ran great.  When I got home I removed the rubber hose from the bulkhead fitting to the primary filter and split it lengthwise on my band saw. The inner layer had delaminated in one area. When cold the engine ran good, but since this hose laid against the engine block, it would warm up and suck partially shut, limiting fuel flow.  Not sure if this is your problem, but something to consider.  Ain't this here Bussin' thing fun!!  Jack
PS: Be sure to let us know what problem turns out to be.

[rv_safetyman]

BK (the real one) I thought you were the winner!!  I have replumbed the return line twice while installing this engine.  Late last night I went out to see if I had left the restrictor out.  Certainly, leaving it out would result in my symptom.  It was there.  This morning I went out and removed the restrictor and tried to blow through it.  No flow,  However, when I hooked up some very low pressure nitrogen (handy) it flowed just fine.  My guess is that I had about 10 PSI on it.  I should have hooked up a gauge, but I got in a hurry.

Sean and Jack.  I have seen hoses act as one way valves when the tube delaminates and tears.  I don't think that could happen with the DOT tubing which is connected directly to the tank.  With the braided stainless hose, there is no way to feel any issues.  The hose is pretty new and it is absolutely top of the line product  As I said, I can have it flow tested if needed.  The braided stainless hose connects from the DOT tubing to the Fuel Pro filter and another braided stainless hose connects the filter to the pump.  I am not using the stock fuel filters.  You can see the condition of the fuel filter with the Fuel Pro.

Clifford, I can not believe the present turbo would not work (albeit not as well), but you are almost always right

Maybe tomorrow I will learn more on my test drive.

Jim

BTW, I checked and DDEC does not have a fuel pressure sensor.  Sure wished that they did.

[JohnEd]

Now back  when I was fighten in the Army we almost always checked for flow AND pressure to eliminate the fuel pump and lines.   Why couldn't you connect one of those little no moving parts fuel pumps to the line at the outlet of the filter and PROVE that there is good flow from the tank AND filter system....including all hose that is new or braided or not.  Take that possibility out of the question and the suggestions have more likely hood of being true.

How bout the hose that connects the filter to the engine? Can you do the fuel pump test at the engine end and prove more of the systems performance?And speaking of brain farts:  can you connect the suck side of that pump to the fuel restrict-er and see if you get flow cause that would  mean it isn't fuel delivery at all.  Could that be true?

John

[rv_safetyman]

Today we made a few loops and I had Pat record some of the data so that I could review it and present a bit of it here.

Before the drive, I had tested the fuel return restrictor.  It seemed to be functioning OK.  I am guessing here, but I could not blow through it, but it did flow at maybe 5-10 PSI  

When I started the engine, I had Pat look at the exhaust manifold blanket to see if she could see smoke. She said she saw a little puff, so there is probably a bit of an exhaust leak at the joints of the three piece manifold.  She said it went away quickly.  I think those joints will seal themselves pretty quickly.

I closed the valves to the Aqua-Hot and transmission cooler, and was able to get the engine up to 195*  With the engine at that temperature, I was able to get 13.8 pounds boost at probably 1800 RPM.  Fuel flow at that reading was about 23 GPH.

The SilverLeaf reports a value called "percent load".  This is a reported value from the DDEC (as opposed to a SilverLeaf calculated value).  It really seemed that I had to work to get that value over 70%.  I did hit 100% one time.  As I recall, on the other engine, the 100% value would pop up pretty quick and easily.  

When we got back, I disconnected the return hose at the bulkhead and had Pat start the engine.  After about 20 seconds at normal idle, I collected about 1/2 - 3/4 pint of fuel.  

Lots of folks are thinking fuel restriction and that sounds logical.  I plan to hook my fairly high volume fuel pump (Holley red) to the fuel system at the pump connection end of the supply hose so that it is pulling the fuel through the supply and delivery hoses along with the filter.  I think that will tell us a bit about the fuel supply system.  I will measure the amount of fuel and time, so that I get a flow rate.

The weather is turning bad again (this global warming thing is killing me ).  I can do the fuel test in the bad weather, but will have to wait to do more testing for several days.  My plan is to change the ECM and see if that makes a difference.  I will also take a look at my mechanical boost gauge to make sure that I don't have a boost sensor issue (forgot to do that today).

If that does not do the job, I should have the turbo from Clifford and will install it (a terrible task in the bus).

All suggestions welcome

[DaveG]

Moving forward, making progress...that's the direction you wanna go!

[Just Dallas]

Removed

[edroelle]

These exercises sure burn time for you - especially when you have many other thing to do.

"The hose is pretty new and it is absolutely top of the line product"

I am probably telling you the obvious.   Diesel fuel attacks some rubber hose/liners.   I guess it would be a long shot that a new hose would delaminate or deteriorate in some way to cause your problem though.   I think there is still a separate SAE spec for hose carrying diesel fuel.  I would be surprised if short term use would cause your problem.

Just brain storming, no need to respond.  Could the cold temps create an environment for this problem?

Ed Roelle
Flint, MI

[rv_safetyman]

Dallas, I think you are suggesting that it could be a manifold/head seal issue.  As I said, I took quite a bit of care to make sure the surfaces were clean and used new gaskets.  I also torqued the heads per spec.  Have you heard of any problems with these parts sealing?  I am with you that I think the two connections where the three part manifolds mate is probably not the issue.  If it is, I would suspect that DD relies on a rusting process to seal them.  If that is the case, it will get better.  Indeed, it kind of looks like the situation is getting slightly better with each test run.

Removing the blankets is not a huge job with the engine on the dolly, but is a job for a contortionist with the engine in place.  I was not very flexible as a kid and the years have not made it any better .  I do not need to remove the blankets to change the turbo (another fun job).  However, I will remove them if there is any doubt (will do so when I switch turbos).

I got to thinking about the Holley pump and whether it will challenge the fuel delivery system.  Turns out that it is rated at 97 GPH.  This pump is old, but it was rebuilt a while ago and never has had much use.  Should be able to test the flow.

Jim