1986 GMC S15 Wont start

Hook up a noid lite to the injector/s harness and see if it flashes if so the injector/s is the problem no flashes could mean power input or the computer injector/s ground drivers-

Noid lite?

The ecm b fuse blew and when I put a new one in it blows imedeitley. I checked the wires that go to the fuel pump and they were fine. The ECM B fuse is the fuel pump. What else runs off that fuse?

The fuel pump relay,oil pressure switch, fuel pump and computer

The manual says the ECM I fuse is the computer and that fuse is fine.

Mit1 says it powers the items I've mentioned earlier I viewed the electrical diagram/schematics

Is the fuel pump relay under the hood? There are 3 relays under the hood.

So i looked at the three relays under the hood on the drivers side fender and the middle relay looks like it fried because the plug and bottom of the relay are black. I cant read the numbers on the relay so I cant cross refrence tot see if it the fuel pump relay.

S15 2.8 liter the FP relay is located on left front fender panel behind AC compressor relay-Sorry no pic available.

Ok. I have replaced the fuel pump relay, ignition control module, computer and oil pressure sensor. It still blows the ECMB fuse even when the computer is unplugged and the key is off.

Time to break out the circuit tester and check for direct short to ground from the fuse all the way to the pump

I know its not the wires from the fuse to the pump cause they are brand new. I did end up finding a common problem with these trucks. The wires that go from the computer to under the hood to the engine. The wires run along the firewall behind the motor rub on the back of the block and short out but is very hard to see anything.