heip 8v92 ddec2

[luvrbus]

Jim does it blow any black or white smoke before shutdown ?

[jimsflx]

jim.i ran the fuel lines into a 15 gallon of fuel from filter and the return line from the head. the motor ran about 20 minuits. when the fuel heated up it shut down. it will start right back up but then only runs 6 to 8 minutes. which is why we think maybe one of the lines on the engine might be collasping.thanks for your advice jim

[jimsflx]

clifford . no smoke thanks jim

[luvrbus]

Doesn't sound like fuel is the problem if it start right back up hope it is for your sake,most of the time when they run out of fuel they will puff black smoke for a few seconds 

good luck

[robertglines1]

Hate ghost!!! If all else fails put a electric pump in line.  See if it makes difference?  what you got to loose.  Keep it for emergency prime for future use.  Would definitely rule out fuel transfer pump. could temporary plumb thru piece of clear hose to watch fuel flow to filters.  Grasping here but eliminating allot of fuel system.   Bob

[robertglines1]

Dumb? Did the Mci have a elect pump in tank that would act as ck valve?  And the engine application like mine out of the prevost depend on the mechanical transfer pump on the engine? If so could the inoperative elect mci pump be the problem??   Just throwing that out there----probably wrong!   Bob

[stevet903]

Did the voltage issues on this ever get straightened out?  The DDEC will stop working when the voltage is 10V or less.  Another thing to check is an intermittent in the ignition line to the DDEC box.  With the ignition on, it should have 12V on it.  If it gets interrupted, the engine will shut off and leave no code, just like turning the key off.  Does it have a rear start switch?  Will it shut down if you start it from the rear?  You can try operating the switch several times and it may wipe any corrosion inside and allow the switch to work consistently.

Steve

[Ace]

Wow usual, lots of opinions but if you read everything you would have read that anything in the tank was eliminated and all the way back to the rear bulk head since the lines were removed at that point. The lines coming from the engine were lengthened and put into a 15 gallon jug of fresh fuel. It made no difference. It still shut down so it's either the pump or a line from there but not going forward to the tank.
There is no smoke before during or after shutdown.
Being a ddec it should show some sort of code after shutting down IF it's being shut down by the ECM. Even a loose connection will give a code as low or high voltage. I should know that one all to well.
I'm no expert but from what I'm seeing I'm sticking to a collapsing fuel line or bad fuel pump.

[robertglines1]

Ace at this point : I forgot about remote fuel supply-- just as confused as most---ghost hunting..That cooler on side of ddec shouldn't be concern. I've broke mine and replaced: didn't see much to it.  Just a observation. suppose to keep ddec cool.  Good luck and do let us know--when you guys find the ghost so we may benefit..Will keep throwing thoughts out.  Some might be out there...   Did he say when fuel got hot?           The exhaust  has not been rerouted closer to the ddec or fuel lines? Mainly ddec...  Again out there... fuel cools DDEC   on my 89 prevost.   Bob

[Ace]

It just seems the returning fuel may be warming up the fuel that would ultimately cause a line to become soft and possibly close off the flow. Yea I'm reaching too but what else to go on with no codes?
I'm leaning on a fuel problem since we just experienced the same type scenario coming back from Daytona in a friends Rv.
Funny thing is how the more it runs and shuts Off the less amount of time it runs!

[robertglines1]

With your bike back ground etc. You know this type of problem .  Let us know.  Might help some one down road. I'll ck my troubleshooting prevot book tomorrow just in case.Some time they do weird apps it their specks. Probably not in this case. Will look though.  Bob.

[luvrbus]

Ace does his fuel pump have 3 lines 1 suction and 2 supply lines ? or the standard 2 lines

[Ace]

I think it's just like mine and standard 2 lines with the ddec mounted cooling plate.

[Busted Knuckle]

OK here is another question about fuel. Does it have a check valve in the return line coming from the head to the tank?
I had a 60 Series that had one of those go bad and it would act similar to this.

Also a way to surefire rule out DDEC voltage issue is to unhook DDEC wires from bus batteries and hook to a 12V car battery sitting there next to the bus. (then hook a 12V charger to it) And see how long it will run then. If it continues to run it's voltage/wiring, if it doesn't that is ruled out.

IIRC correctly you said you tried another 8V DDEC right?
  BK 

[Ace]

After they installed two new  8D batteries the voltage appeared to stay more consistent in the mid 12v range fwiw