losing fuel pressure on my 2011 DD15 Cascadia

I have followed this thread for my DD16 that is losing prime too. I have done the pressure test and found the pressure coming out of my blow-by tube. So I'm assuming it can be the injector rails or cups? It just had a head gasket job done. Any confirmation or advice would be great.

 

what kind of pressure test you have done ?

 

What have they replaced so far or took apart and checked?

 

Myhn are you suggesting this is the fix? I have a 2010 Cascadia and am losing prime overnight, once I get her started she is fine the rest of the day and then lose prime overnight, etc..

thanks

 

yes. one of the valves in fuel filter module leaks..

 

I run a 2011 Cascadia with a dd15. Last week all of a sudden my fuel system lost pressure overnight. Primed it with hand primer, started right up and ran fine. Next morning same thing.
Went to freightliner dealer and got a new Bypass Gallery Valve, part # A4720780549, which fits the 3 filter setup for $100.
Drained filter, removed old valve with metric allen wrench, installed new valve. Primed system, started right up. Problem solved.
Note. Draining the filter housing takes about 1 gallon of fuel, use a 1 gallon milk jug to catch fuel. Dont freak out if a few ounces of coolant comes out, make a note of it and redrain the system in about 6 weeks to see if there is more. If it is, you might have an injector o ring leaking a tiny bit. As long as you're only getting about 4oz you're good.
This is a 1hr task at most. The new valve has a different size allen wrench head vs the old one. These are METRIC allen wrenches!!! The valve is made of aluminum so dont try to put gorilla force on it!! This valve has also cured the very slight "engine loping" I noticed a few mornings while warning up.

 

Hi. What problem did you find ?
My 2015 dd15 also loosing prime overnight . Hard start in morning , seems fine after 30 minutes of ideling .

 

Hi . I'm also having the exact same problem . I got 2015 Cascadia with DD15 in it , it got 1.3m miles on it . Loosing prime overnight . takes 10 cranks every time i park it for 10+ hours . Then goes fine for rest of day .
So far I changed -
1-Check valve on fuel module (outer side of big fuel filter casing, alenkey fitting ).
2-Check valve on end of fuel pressure line . ()
3-Check valve on fuel water separator(spring loaded plastic ball).().
4- Check valve (on fuel module , right under of small fuel filter) had to remove black tyre cover to get visual access of it .( ).
5- Ball type release valve(inside, underneath of small fuel filter ).

I change all those 4 one by one . Drove truck at least 4 days between each other .
Still having same problem . Bought small fuel filter cap (found there is no collar left for rubber ring , and decided to change it ) changing it tomorrow .
Please let me know how you found success in your case . Thanks !

 

Did you ever resolve your issue? What did it end up being? Thanks!