I have a 1987 F250 lariat with a 7.3 liter non efi (from what i was told im unsure)
The truck is not getting fuel with a full tank of diesel.

Here is a list of the troubleshooting methods ive used

Removed Fuel Tank Selector Valve and blew air through source lines to ensure they were not clogged.

Checked that Selector valve is working properly, and it is though its stuck on front tank

Attempted to bypass selector by disconnecting lines and creating my own verzion of a tank direct connected bypassing the selector as if it had one single tank

new mechanical fuel pump installed

new fuel filter

bypassed water separator

checked pressure from check valve, very very low below 1

Issue at hand is that I am currently getting fuel in lines passing the tank selector, however it is not making it to the next stage in its travel which is the water separator. As mentioned I have very low pressure when turning over the engine. No fuel, not even a drop is making it to the fuel filter.
If anyone has any ideas please feel free to contact me here or personally at gantt.jacob@hotmail.com sincere thanks for any help or ideas provided.

 

get a pump out of a chevy duramax and install it in the line,a nd hard wire it. I've done that to a few trucks.