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Author Topic: Well we are ALMOST broken down!  (Read 4226 times)
Dreamscape
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1968 Silver Eagle Model 01 8V71 Allison 740 #7443


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« Reply #15 on: September 26, 2009, 08:26:54 AM »

Yip, you got it, and Thanks to Clifford, you know the whole truth!  Wink

Paul
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Becky and Paul Lawry, On The Road
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« Reply #16 on: September 26, 2009, 08:53:06 AM »

John, you may have a ground problem the next time it does not start check the ground on the ECM  where it grounds to the block then try it and see what happens.   

good luck
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« Reply #17 on: September 26, 2009, 09:49:31 AM »

I had the same thing on a 60 series at one time and found that there is a fittig with an orfice at the back of the head in the return line - mine was missing. Not having it allows it to lose prime thru the return line - ONCE IN A WHILE! Check to see if you have a restricter in the return line at the rear of the head. Just MIGHT be the problem.
JimH
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Started with nothing - still have most of it left!
1963 Eagle 01 with Detroit 60 series done (Gone-sold!)
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John316
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« Reply #18 on: September 26, 2009, 04:44:33 PM »

I think that it is a fuel problem. Even though we don't get ANY exhaust, or white smoke, while starting, I still think that it is fuel issue. It didn't want to start last night, and then this evening it didn't want to start.

When it didn't start this evening, I then went back and checked the ground. All good. Then I went and ran the primer pump, as me and my buddy talked a little. I then hit the starter again, and it rolled right over, and started right up. I am thinking that my next plan of action is to replace the pump on the back of the engine (it would be the front of the engine in a truck).

So we will try to find a Detroit place that is open tomorrow. We are heading towards Melbourne, Fl, and will be there tomorrow and Monday. At least that pump isn't hard to replace. If that isn't it, I am not sure what I will do next, but we will see.

God bless,

John
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MCI 1995 DL3. DD S60 with a Allison B500.
Len Silva
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« Reply #19 on: September 26, 2009, 04:55:41 PM »

John,

Hard to tell without being there but I suspect a suction side leak or a bad check valve. I would double check every connection and filter before spending the money for a pump.

You might try leaving the primer pump running for a while without starting the engine and see if you spot any fuel leaks.  Suction side leaks can be very hard to find.

Len
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« Reply #20 on: September 26, 2009, 05:09:04 PM »

Check valve - $35
Fuel pump - unknown but I'm guessing $500 +
Symptoms favor the check valve.

I know which one I'd be changing first.

YMMV
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Len Silva
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« Reply #21 on: September 26, 2009, 05:13:45 PM »

If it's anything like the check valve on my 4104, it's field reparable, maybe need an O-ring.
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« Reply #22 on: September 26, 2009, 06:15:14 PM »

yeah keep it simple.  I'm new to DD but not to engines and that does not sound like a FP.  Lot's of times people jump to the worst conclusion.  Hey here's a simple diagnostic, park on a hill, head up with a full tank of gas, see if it starts then.  I'm betting it does.  BTW the FP is working much harder at full throttle, I would be looking there for reduced performance
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John316
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« Reply #23 on: September 26, 2009, 06:38:52 PM »

So if it isn't the FP, maybe the check valve.

The really strange thing is, that I don't get any exhaust (colored anyways). I would have thought that if it was loosing the prime, that I would have gotten a start, and then it would die. However, it when it starts, it starts RIGHT up when it does. The other strange thing is that it doesn't happen every time. It is so random (it started right up after sitting overnight, and didn't start after it was warmed up and had been sitting for only an hour).

Does that info add anything?

God bless,

John
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johns4104s
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« Reply #24 on: September 26, 2009, 06:57:09 PM »

busguy01,

I had the same problem on my 4104/671, it just would not hold prime. So I found that there was a one way check valve allow the prime to drop. Changed it out and it starts on the second rotation.

John

PS I have also had trouble on both my MCI 9 8v92TA and my 4104/671 with the skinner valve not releasing the air to allow the rack to reset. A friend had the same problem 4 weeks ago with his Eagle/871. Actually it turned out to be a bad plunger on the 8v92TA.
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« Reply #25 on: September 26, 2009, 07:06:34 PM »

To me the lack of smoke directly means no fuel going into to the cylinders. The intermittent nature of it sounds all the more like something that is sticking sometimes and sometimes not.  (i.e. check valve) 

Perhaps, sometimes it sticks open allowing fuel to drain back to the tank.  Sometimes it doesn't stick so the system stays primed and starts right up.  When it loses prime, initially there is no fuel going into the cylinders, therefore no smoke.

If replacing the the check valve is within your skills and the tools you have with you, I would try that before putting myself at the mercy of a $120/hour DD shop.  Even if you aren't comfortable that you can do it on your own, there are many bus nuts in Florida.  I'll bet you could find one that would help you do it.

Then if it turns out not to be the check valve you are out less than $50.  But if that fixes it, you will have saved hundreds of dollars.
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John316
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« Reply #26 on: September 27, 2009, 06:04:44 PM »

Thanks a lot guys. I will make some phone calls on Monday, and see if I can get another check valve. I think that will be the one right on top of the tank, and I think that I will be able to do it myself.

Thanks a lot, and I agree that it is a fuel issue. The check valve makes sense.

God bless,

John
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« Reply #27 on: September 28, 2009, 07:37:29 AM »

As has already been suggested, before replacing the fuel pump, check for low fuel pressure codes.  Or, check it mechanically at the pump outlet.   
Install a fuel pressure guage in the pump outlet line.   Get fancy and install a dash fuel pressure guage. 
If low fuel pressure is your problem you'll see it. 
My bucks go on a fuel line check valve or some such.   I cannot see an S60 mechanical fuel pump being intermittant...could be...I have seen S60 drive gears fail...but that isn't likely.
A crack in a hard line, fuel tank pickup, or a bad flex fuel line will cause loss of fuel prime and intermittant start.  Eventually cause an intermittant run condition.
Do you smell diesel fuel along the side of the coach?   Might seep a little when shut down if faulty fuel line...suction line.  The return line likely isn't your problem.  Any check valve on the suction or return side could be your problem.   Does your fuel primer pump have any check valves?    Does it serve as a check valve for the fuel system?
Reading any stored DDEC codes will also rule out other problems.  It's possible that the DDEC ECM won't view low fuel pressure while cranking as a problem.  Faults must exist for a specific time and you may not be cranking long enough to set a code.   Someone may be able to expand on this...?

Good luck, JR





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JR Lynch , Charlotte, NC
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« Reply #28 on: September 30, 2009, 07:49:38 AM »

Thanks a lot guys. JR, great post. I agree with you, I don't think that it is the pump either.

The check valve is what I keep coming back too. Dallas explained everything to me last night. Makes sense. I think is what is happening, I hit the starter, and it doesn't see fuel. Well, the DDEC won't let it fire (hence there is no exhaust, and it also doesn't start then die). I am going to wait to fix the check valve until we get back. I would sure hate to break something else, in there, and be down for a while.

Thanks again for all of the help. You guys are great!

God bless,

John
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« Reply #29 on: September 30, 2009, 08:02:45 AM »

John, I may be wrong as I have before but if you are not getting the 48 code it is not a fuel problem.
Try disconnecting the high temp fuel sensor on the filter when it does it again.Owning a DDEC the best investment you can make is a Pro-Link or the DD software for a laptop.
Cole gave me the software and I like it better than Pro-Link easier for these old eyes to see and easier to use.



good luck
« Last Edit: September 30, 2009, 08:11:47 AM by luvrbus » Logged

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