I have a 1992 Chevy 1500 1/2ton 4.3L 6 cylinder. Been having this problem this entire past week. Whenever i turn the key to acessory the inj a+b fuse will break. I know this is the fuse for the fuel pump, fuel injection. I have replaced the fuel pump, the fuel pump relay, i have looked at the wires and none of them seem to be bare or messed up. After all this the fuse still keeps breaking when i turn the key to acessory. Ive had multiple people over to look at it and none can think of what could be the cause of this issue. I used a meter and did see that the fuel pump isnt reading quite as high as it should be but not extremely low. If anyone could help me troubleshoot this id greatly appreciate it. Thanks

 

Try unplugging the electrical connector to the injectors and see if it stops blowing the fuse.