I'm working on my father's 07' Trailblazer. The other day he started that on his way home that his trailblazer started to spit and sputter. He pulled of to the side of the road and shut the vehicle off for a few seconds. Turned it back on and it seemed to be ok except now his speedometer started to mess up. When he turn the ignition on the speedometer would drop below O mph. While driving the speedometer would increase but ticking like the second hand on a clock. He gets home and the vehicle stalls and dies right in the drive way. Tried to start the vehicle and it ran for like 2 seconds and stalled again. Tried to start it again, only crank no start.
I check for fuel pressure on the rail, no fuel pressure whatsoever. Checked fuel pump relay by switching out relays with other relays in the underhood fuse box. Nothing, still no fuel pressure whatsoever. Dropped the tank and replaced fuel pump because it was still under warranty. Still no fuel pressure with the key in the on position or trying to crank/start it.
During these checks of turning the key to on position, on a few occasions, when I turned the vehicle to the on position (not run) the vehicle tried to start for like a split second. This definitely has me scratching my head. I heard or read that the PCM can also stop power to the fuel pump relay and cause many other problems. All ground wires look good and are tight upon inspection except that the bolts and connectors look rusty but no corrosion. Any ideas if to what my problem could be? I was leaning towards a corrupted/bad pcm but maybe a bad ignition switch. I just don't understand why everything else works when you turn the vehicle to accessorie/on but no power to fuel pump.
I check for fuel pressure on the rail, no fuel pressure whatsoever. Checked fuel pump relay by switching out relays with other relays in the underhood fuse box. Nothing, still no fuel pressure whatsoever. Dropped the tank and replaced fuel pump because it was still under warranty. Still no fuel pressure with the key in the on position or trying to crank/start it.
During these checks of turning the key to on position, on a few occasions, when I turned the vehicle to the on position (not run) the vehicle tried to start for like a split second. This definitely has me scratching my head. I heard or read that the PCM can also stop power to the fuel pump relay and cause many other problems. All ground wires look good and are tight upon inspection except that the bolts and connectors look rusty but no corrosion. Any ideas if to what my problem could be? I was leaning towards a corrupted/bad pcm but maybe a bad ignition switch. I just don't understand why everything else works when you turn the vehicle to accessorie/on but no power to fuel pump.