I have a problem with my fuse pump relay fuse popping each time I try to Crack with the battery at full charge. Sometimes even starting but soon after the fuse blow. I been trying to trace wires but my mechanical knowledge is the basic to keep the car on the road. Please help I'm trying to restore Grandpa's Truck.

 

Could you please explain, "Crack the battery at full charge" ?

 

So it turns over when the battery is low and it blows the fuse when the battery is fully charged or at full voltage.

 

So we are on the same page,
When we are attempting to start the engine the starter turns the engine over.
When the engine starts running , it fires up and runs.

Not sure where you are when you say turns over, can you help out here?

If the charger you are/may be using, is causing excessive voltage to the system , it can cause fuses to blow.

If the in tank fuel pump is jammed and cannot operate it will cause the fuel pump fuse to blow..

There are 2 relays that are responsible for fuel pump operation , they are both the same and can be interchanged
There is an inertia switch in the system to prevent gas being pumped out in the event of an accident. It should be located over the tunnel inside the cab to the right of the gas pedal at the firewall. Make sure nothing has been damaged there .