[Jack Houpe]

Might be turbo locked up or perhaps a big leak between the turbo and the intake.

[Tf175]

The '86 engine should be mechanical , not DDEC .
Get to the turbo Inlet,  see if it turns freely without a lot of axial play . Do the vanes look okay ? 
Look for leaks on the exhaust side of turbo .

There could be problems with the injectors , racks, etc . 
Throttle travel is a good place to look . On my coach air from pedal goes to the Bendix cruise control . There is a cable from the cruise to the throttle lever on the governor . 
I have a file with air pressures I measured at one time , will look it up. 

Many threads on the forum regarding air leaks .
Single axle should have four air bags rear , four front . 
Get a sprayer full of kid's bubble liquid . 
Most importantly be very careful under the coach .
I bought HF 22 T jack stands , use cribbing as well .

[TerryW]

On further inspection, it revs up in neutral to about 1500 and if you hold it there for a moment and release it will idle.down and die.
Sounds like a fuel delivery problem. Does anyone know if there is an electric fuel pump on these things and where that might be???
Also verified that the throttle is moving full wide open.
Working on the air bag problem now

[Tf175]

No electric fuel pump unless something has been added . The fuel pump is basically a transfer pump , the real pressure is developed by the injectors . Timing adjustments on fuel racks critical. 
As has been mentioned,  try feeding fuel from a 5 gallon bucket or similar . 
There is a feed tube in the top of main fuel tank .
Could be something wrong with that . Mine is just forward of the entry door , under a bottle rack .
Definitely sounds like a fuel issue. 
There are 8v92 TA manuals online in pdf form , I find very informative. 
 
You Tube videos by Bus Grease Monkey are also a great source of information.  He has many videos addressing power loss . 

For what it's worth , when we bought our coach in 2017 I was going to fix everything in a couple of weeks ...

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On further inspection, it revs up in neutral to about 1500 and if you hold it there for a moment and release it will idle.down and die.
Sounds like a fuel delivery problem. Does anyone know if there is an electric fuel pump on these things and where that might be???
Also verified that the throttle is moving full wide open.
Working on the air bag problem now

Quick sanity check to see if it’s getting fuel is to pull the fuel filter and see if it’s full of fuel. No fuel or fuel not up to the top means you have a problem. All of the fuel lines going to the engine are under suction, so they can suck air but not leak fuel. Need to look at all the fuel lines and anywhere else it can suck air into the fuel line. I trick I use to prime the system is to use a vacuum and put the hose on the outlet, blower side of the vacuum and put it in the fuel filler with a rag around it to pressurize the fuel tank and push fuel to the engine. I usually crack open a line u til is see a constant flow of fuel. I just went through this procedure today and finally got a Newell started. More on that in another thread.

[TerryW]

On further inspection, it revs up in neutral to about 1500 and if you hold it there for a moment and release it will idle.down and die.
Sounds like a fuel delivery problem. Does anyone know if there is an electric fuel pump on these things and where that might be???
Also verified that the throttle is moving full wide open.
Working on the air bag problem now

Quick sanity check to see if it’s getting fuel is to pull the fuel filter and see if it’s full of fuel. No fuel or fuel not up to the top means you have a problem. All of the fuel lines going to the engine are under suction, so they can suck air but not leak fuel. Need to look at all the fuel lines and anywhere else it can suck air into the fuel line. I trick I use to prime the system is to use a vacuum and put the hose on the outlet, blower side of the vacuum and put it in the fuel filler with a rag around it to pressurize the fuel tank and push fuel to the engine. I usually crack open a line u til is see a constant flow of fuel. I just went through this procedure today and finally got a Newell started. More on that in another thread.

Hmmm. As a matter of fact I did notice low fuel in the second fuel filter when I went to change it.

I did get the coach leveled up by taking apart the passenger side rear leveler and kinda jury rigging it. But no joy on the engine.

We headed home and I'll have it towed to a local shop tomorrow/Monday morning. I'm sure it's something to do with fuel and/or the shutoff rack thingy.

Is there an online shop manual for the 8v92? It would really help.

[dannymarilyn]

If the coach sat unused, ensure the fuel tank vents are clear. Dirt dabbers and wasps, or spiders can clog those vents making it very difficult for the fuel pump to pull fuel from the tank against a vacuum. Quick check is to just remove the fuel tank cap.

deg

[Tf175]

https://www.wanderlodgeownersgroup.com/d...-and-P.pdf

[TerryW]

Thank you TF175 and thanks to Igor Chudov, That is going in a binder in the coach, very nice.

I'm rethinking my approach here:
The turbo spins and has no free play, the engine always starts but sometimes stumbles down and stalls when left to idle or if it's revved up for a bit and then let go to idle it will also stumble down and stall. There is about 150 gallons of fresh diesel in the tank now, and both fuel filters are changed. At full throttle it will just barely make second gear and about 20mph and zero boost on the gauge. I don't see anything obvious in terms of exhaust or boost leaks and for the power to be this low they would have to be massive leaks, right?

There is a local shop near Quincy IL. that says they can tow it and "maybe" has access to an oldtimer who knows 8v92's
Before I throw in the towel and call for a tow & a "maybe" mechanic, and mainly just because of pure Scottish stubbornness, I think there are at least two tests that I would like to get some feedback on, from you gurus.

I think these were mentioned earlier:
1, Pull the fuel line off the secondary filter and run it to a fresh diesel tank, if this resolves the problem, we know it's upstream, if it does not fix the problem, we can assume it's downstream (perhaps the fuel pump) or not related.
2, Pull the vale cover and check that I have full travel on the injector control tube under throttle, if I do, it is probably not the governor, if I don't, it indicates the governor isn't allowing full fuel when I'm at full throttle.

Do these two tests make sense to you? Any other you would suggest???

Thank you all for your help here, this one is going to be a lot of work, but I think it's worth saving it. I'll post the coach number as soon as I figure that out.

[Tf175]

Step One . 
Feed fuel into the secondary filter under pressure using pump up sprayer pump or other .
Procedure can be found on the site using the search engine . 
I used a 12V diesel pump , Mr Gasket , sourced from Auto Zone .
There is a plug on the secondary filter boss that can be plumbed into . 5 gallon pail will be drained amazingly quickly as the fuel will still be returned to the fuel tank . 
Vent blockage was mentioned . My coach has a coiled 3/8 hose from the vent , target for dirt daubers as mentioned . Look on top of main tank , passenger side .
You could could try it with filler cap removed of course . 
If you can actually find a Detroit two stroke mechanic , that's a good thing . A rare breed these days . 
Scott , Bus Grease Monkey, is located in Tennessee . 
Good Luck ,
Chris