help 94 4.0 Fuel pump power issues

[EHford]

hello everyone,
Im new to the forum and need some help.
94 4.0 5 speed 4x4 fuel pump issues
new pump(working and tested with 12v)
new filter
was driving fine but started cutting out on a hill climb, found the starter wire shorted on the exhaust manifold
getting 12v at pump with key on but wont run pump
getting good ground at pump(tested continuity and no resistance)
getting 12v at inertia switch
inertia is bypassed
changed out fuel pump relay and the diode
when i jump the relay the fuel pump runs
any ideas? thanks

 

[bobbywalter]

are you straight lining 12 v at pump? load test the 12 v you get at the pump. that isnt right but may be back feed potential.

assuming you are jumping actual fuel pump relay, and truck runs when you do this

test relay.

check for key power at what is usually a red wire which should be relay switch supply side

if that is good then manually ground switch side. if it works there is a signal issue from ign to ecm or the ecm is burned and not allowing it to ground pump relay.

cracking open the processor may show some evidence of damage.