Detroit 60 (help)

If the check valve was replaced then I'd be looking at a fuel pump.

If it was sucking air then that would give you ruff running symptoms.

The fuel pump acts as a check valve also so fuel cant drain back to tank. Good possibilty why your fuel filter is half empty

 

1. Did you disconnect the fuel lines from this? looks like it has been out of the loop for a while
2. If so, is that when the trouble started?
3. What kind of fuel filter system do you have? davco maybe

You are losing prime somewhere like has been mentioned before.
1.fuel filter check valve if equipped a davco has those. a small plastic piece
2. back of head check valve that you say you have fiddled with
3. fuel pump
check those and check back in

 

Guys I bet he is talking about his davco water separator and not his fuel filter.

 

just install a new one. they are very cheap. when you open the system you will have to purge the air out. since you don't have a davco, make a plug that will go into the filler neck of the draw tank. rags, plastic bottle, something. insert shop air thru this, and while you turn the engine, apply the air into the tank, low pressure if you can regulate it. this will force the fuel thru the pump, filter and into the injectors. the new pump will not be able to pump the air pockets out of the system. you can fill the filter up if you like, but really no need as the pressurized fuel will purge the pockets of air out as the engine turns. Hope this helps. Johnny

 

If a device or whatever is attached to the truck is bypassed and deemed of no use, discard it, get it off the frame. If you are absolutely shore it has no value to the truck as it sits today.

I did not consider the water seperator.

Water was not a think in my time with high sulfur fuels long before 2001. I consider any fuel after 2007 to contain water. The one thing you cannot have in a motor vehicle.

 

I’ve never seen that. Looks like if it’s discarded, you may need to replace pos and negative cables, including the small ones. Looks like they left it in place, as a junction block. Because they spliced it in between the battery and starter. Need to see where those wires all go, At least clean them up, eventually eliminate it, replacing cables as needed.