Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Well, that just about eliminates any of the ignition system as the problem and most likely the fuel system as well. That leaves mechanical. I would do a compression test and then if that fails a cylinder leakdown test to determine if perhaps the piston rings are stuck, broken or just plain worn out. That would also check that the valves are seating and the head gasket. On a 2000 the computer should have at least told you what cylinder it is, so if the code is P0301,P0303 or P0305 that would be on bank 1 or the same side as cylinder #1. If P0302, P0304 or P0306 that would be on bank 2, so remove the valve cover and measure the camlobe lift to make sure the camlobes on that cylinder are not wiped or flattened down. It could also be a bent push rod, rocker arm stud pulled out of the head, so let the engine idle and look for anything loose or making noise.
Ok, I was just double-checking cause the vin X 4.3L fuel pump psi was 41-47psi and spark plug gap of 0.045". The vin W is 0.060" so you do have them correct. I am just a bit concerned about the low fuel pressure. Perhaps the ecm and O2 sensors are overcompensating for that and making it run rich. Do the spark plugs smell like gas when you clean them?
Yeah, P0300 is a random misfire code. You might want to consider replacing the fuel regulator.
look back it's a new spider and the real misfir is on #3 what time will you be on tomorrow . haven't eaten today & wife is hungry give me a time & I'll meet you back here
I'm on by about 8-9 am in the morning. But before you go here is something to think about from the Chilton manual on fuel pressure lower than 55 psi.
"15.If the fuel pressure is less than 379 kPa (55 psi) at idle, it falls into the following 3 areas:■The pressure is regulated but less than 379 kPa (55 psi).The amount of fuel reaching the injector is sufficient, but the pressure is too low. The system will run lean, hard starting cold, no start, overall poor performance, and may set a DTC. Refer to Engine Cranks but Does Not Run .■A restricted flow causing pressure drop -- Normally, a vehicle with a fuel pressure of less than 300 kPa (44 psi) at idle is inoperable. However, if the pressure drop occurs only while driving, the engine will normally surge then stop running as the pressure begins to drop rapidly. This is most likely caused by a restricted fuel line or plugged filter.■A leaking or contaminated pressure regulator valve or seat interface may not allow the regulated pressure to be achieved."
"A lean condition may result from the fuel pressure being below 414 kPa (60 psi). A lean condition may cause a DTC to set. Driveability conditions associated with lean conditions can include hard starting (when the engine is cold), hesitation, poor driveability, lack of power, surging, and misfiring."
"Fuel pressure that drops-off during acceleration, cruise or hard cornering may cause a lean condition. A lean condition can cause a loss of power, surging, or misfire. You can diagnose a lean condition using a scan tool. If an extremely lean condition occurs, the heated oxygen sensors will stop toggling. The heated oxygen sensor output voltages will drop below 300 mV. The fuel injector pulse width will increase."
well it gives me something to do tomorrow. will pull top off for 7th time and put old spider back it & try as don't have vac line to pull off on this one. but it's always #3 that gets black like it not firing. will get hold of you in am have good evening
If its only #3 then it may not be the fuel pressure. If the black stuff is oily then perhaps you have a worn valve guide and/or bad valve guide seal and oil is entering the combustion chamber and fouling that spark plug.