I have a '98 Blazer with the 4.3L Vortec V6 that has been driving me crazy for over a year and nobody seems to be able to solve the issue. Clock shows 110K. Engine still is very strong when problem is not present.
The symtoms: Intermittent no start condition and intermittent misfiring. Cranks fine. Will kick a few RPM immediately after the key is released, then die. Runs very rough, though it will sometimes run like a top with no signs. Sometimes smell gas. Can get to fire if I remove the air cleaner feed to the throttle body, open the throttle wide open and then it will often start, then predictably die.
Once started, it will run rough with obvious misfires. On occasion, it will run very well though. Once started, it can be restarted unless it sits overnight.
It started out only acting up when the weather was damp if left overnight. Then it became more frequent and will do it when not damp. Seems worse if left overnight.
Throws a multiple cylinder misfire code. Technicians have told me that all cylinders show a misfire, not just one or two.
What's been done: everything in the ignition circuit has been replaced (cap, rotor, coil, module, plugs, wires, pickup coil, TPS). The fuel pressure was measured at one time and was reported to me as being OK, but I'm not too confident in the tech.
My guess: 1) fuel is dribbling from the injectors and is flooding the engine. 2) fuel pump pressure is low. 3) ECM is acting up.
Any ideas are REALLY welcomed! Please help me solve this issue. When this thing runs well, it can be a very smooth engine and still is strong.