1994 Chevy Silverado V8 Two Wheel Drive Automatic
Have changed fuel pump, relay, distrub, module, coil, and pigtails on coil, cap and button, ecm, oil pressure switch and still get no spark and no fuel all started after changing pigtails on coil and jack up to replace brake line. Will turn over just fine but no power going out of fuel pump relay power going in. Also have twelve volts going in coil and coming out just nothing when try to start. Replaced everything can think of and nothing changes.
Use a gage and check fuel pressure. For TBI around 10 psi. Because of the oil pressure switch that is wired in parallel with the relay, once you crank the vehicle enough to bring up oil pressure and the switch closes, the pump will get voltage even without the relay.
Use a noid lite and check for injector pulse, engine cranking. Use a test lite on the negative side of ignition coil, the lite should pulse with engine cranking.
Without trigger signal, the ignition module doesn't know what to do. No ground pulse on the negative side of coil. Also, when you crank the engine, does the distributor rotor turn?
October, 4, 2010 AT 9:33 AM
Yes had pressure before fuel pump wont even come on now and the distr. Is turning replaced it had crack in pick up coil so changed the whole thing out. Along with coil has brand new MSD coil and also changed out the oil pressure swith had one go bad before and that was the first place I started. Havent checked the pulse on coil yet but do have 12 volts coming in and out of coil. Also checked fuel pump relay have one wire with 12 volts.
October, 4, 2010 AT 10:46 AM
My hearing is no good, I can't hear the pump run with engine cranking, I have to use a fuel pressure gage. Have a helper crank it, while you check for B+ and ground for the pump motor at the fuel pump connector. Gray wire is voltage, black is ground. If no voltage check the fuel pump fuse. In the diagram at the firewall, #3 is the relay, #15 is the fuel pump fuse.