1985 F250 Ford plumbing

 
I am writing because the manual that came with the truck labeled Ford/ Chevy/Dodge mechanical lift pump clearly shows the lift pump after the diesel filter. When I switched to WVO, it would go though the diesel filter before the lift pump. I had to drive 5 miles to run out the WVO out of the diesel side. I figured this out after I burned out the glow plugs. Now for the fun part, I found the “Flush” Valve, next to the diesel tank under the bed of the truck. When I purge the unit of WVO it goes into the diesel tank! I plumbed the diesel filter before the lift pump and it works. Can some one tell me how to plumb a 6.9 ford diesel? I still need to work on purge. Cheers! Jim