ok i have and idear!! Bear with me. Ohm's law states that it takes one volt to push one amp thru one ohm of resistance. More resistors, less flow. Did you check your return circuit? 80% of the fuel going into the ip is for lubrication cooling and to heat the fuel tank. if that is restricted it would back up the whole system like a squirrel in a shower drain (don't ask, please.)
Just an idear.....

__________________
I like cars.