C15 starting issues.

Yes that is the one I just replaced.

 

The fuel comes from the bottom of the tank and returns on the top side.

 

After taking what I believe is the primary fuel filter (on frame) off I noticed that it has the washable cat filter part # 9m-2342 is this factory?

 

I’m not sure what motor prefix it is as I can’t find a tag anywhere on the motor. I don’t think it’s a air/leak issue as I can hear the fuel returning to the tank as I’m hand priming the system

 

Also should the fuel check valve have a oring on the threads closest to the 1” head? The old one I removed didn’t but when I bought the new one from Peterbilt they sent me with one. Wondering if this could be keeping check valve from seating.

 

I have one on it now, I’m just trying to figure out why fuel is returning back to tank. I have ANOTHER new check valve coming today. Fingers crossed that fixes it. I removed the line that goes to tank abs hand primed it and it builds up pressure

 

Update- I put another check valve and I also replaced the other check valve that’s on the filter head as well, it’s still doing the same thing!
I put a fuel gauge on it and I’m only getting up to 10-15 while cranking and you can hear the fuel returning to tank.

what else could it be?