My 1989 V6 truck died in the street on me. Got a jump start and made it home before it died again in the driveway. I thought is was the altenator (was pretty old) so I replaced it with a new one. Altenator works -I had it tested before I left the parts store. I installed it and jump started the truck and it started and ran fine until I disconnected the jump cables. The motor died out. Jumped it again and it started right up and dies when I took the cables off.I have checked all wiring and fuses and cannot find why no electrictyis going to the motor or battery.

Down and out in Va.

 

i dont know what the wiring looks like on the 89's but look at your wires going to the battery from alternator and wire going to fuse box and starter from battery. there could be a bad wire thats causing the drop in flow. a great way to check wires is get out the volt meter. check between alternator and battery, battery and ground, and just check check check.