truck dieing/bogging on highway

[xsmokey11499x]

Originally Posted by scoutboy74

Thanks for the added clarification. To me that's clear indication that you have at least a partial blockage either inside the tank or in the line running between the tank and pump as stated previously.
Now what about the block-mounted mechanical pump? Is it still in place or was it removed in favor of a block off plate? If still there, do you know its condition?

blocked off with a plate

[scoutboy74]

Okay. Let us know once you've gotten good flow from the tank to the carb. Then we can see about getting your fuel pump pressure measured and properly regulated. Or you may want to consider going with a replacement mechanical pump for simplicity sake.