3406E Losing Prime

tank breathers are clear. truck idles around 75psi. we replaced the fuel filter housing on the engine with a brand new unit. and put a one way check valve at the top of the suction at the tank so if it was draining back that would stop it. Is it possible bad injector orings could cause this issue?

 

Does it still start fine but quits after 30 seconds or so??

What did you do with the filter housing on the frame.?

There is also a one way check valve on filter housing on engine but I'm guessing you prob changed that already?

 

yes still same symptoms. didnt do anything with the housing on the frame. this engine doesnt have the check valve on the filter base.(but yes the check valve was replaced) it has its own fuel distribution block. See image.

 

It' Is not your injector O RINGS. I say this because of the fact it starts fine and runs for 30 seconds. If it was on the pressure side of the fuel system it would not start.

It has to be on the suction side.

I would bypass the filter housing on the frame by joining the lines together. Probley a #10 JIC MALE×MALE.
Run it a day like that to see if your problem goes away. You won't hurt anything by bypassing it for a bit to see.

 

after shutting the truck off the pressure in the system drops to 0 within 5 minutes

 

AGAIN. it starts fine, it is not a pressure issue. Cats need No air and good pressure to start........

It' Is picking up air from the suction side somewhere.

 

Just throwing this out there... I have a C15 and it would lose prime after it sat overnight. It was a bad fuel transfer pump.

 

Yes This also^^^^^^

We told him that already.

I'l repeat again. It' Is on the suction side.

 

can the transfer pump still be bad even if its putting out good pressure?

 

I agree fully with @swaan on this.