MAJOR problems with 2000 Blazer HELP PLEASE!!!

I have a 2000 chevy blazer that has major problems. It ran great when I first got it and now its not even driveable. Here is the lowdown on it. It started out by missfiring or losing power for a split second when accelerating, but only when the rpms were at or right around 3000. It would also only do this when the temperature outside was about 40 degrees or lower. When doing this it would cause the blazer to jerk back and forth just as if you were to accelerate then let off then accelerate then let off. It would also make an "electrical shocking" type noise in the engine compartment right in front of the drivers side.

Well it started getting worse slowly by doing that at warmer and warmer temps. Now it will do it at any temp and after driving it for a few hours(sometimes less) it loses all power. So when you try to accelerate it wont even rev the engine up. I can slowly "feather" the pedal to accelerate but when you push the pedal to the floor all power is lost and the rpm gauge falls to almost 0.

It also recently started dying when the fuel tank is at half or below and you stop fast. Along with the dying if you have half a tank or lower and allow it to sit without driving it for a day or 2 it is very hard to start.

Myself and my father are both mechanics so we know what we are doing when it comes to vehicles but this one has us and everyone else we have talked to about it stumped. Here is whats been done to it thus far to try to fix it. Spark plugs replaced. Fuel pump replaced. Fuel filter replaced. New catalytic converter put on it. Everything else has been looked over and seems to be ok. The hardest part to diagnosing it is its not throwing any codes. We did scan it a while back and there were quite a few missfires detected but still no codes were stored on the vehicles computer.

Any help at all getting this thing fixed and back to running would be very appreciated. I have heard that blazers are electrical and computer nightmares so maybe thats whats wrong with this one I have no idea. So HELP PLEASE!!!!! :)

I saw what you replaced, didn't see any testing? Did you check for spark at the plugs? Did you use a gage and check fuel pressure? Use a scanner that will show live engine data, look at the fuel trims, is it running rich or lean? Are the engine sensors showing the proper signals?

Ya before replacing each thing the propper testing was done. The scanner says the engine is running a little rich, the crankshaft position sensor was bad according to the scanner so that was replaced, and the scanner is also saying that the oxygen sensor readings are bad. But other than that everything is within specs.

Did you perform the crankshaft position sensor relearn after replacing the sensor? Whenever the sensor is moved, removed, replaced or disturbed in any way, the relearn is mandatory. A capable scan tool is necessary to perform the relearn, the cheapie code readers won't do it. Have the relearn performed before doing any other diagnostics, or you'll be chasing your tail ;)

"The scanner says the engine is running a little rich, the crankshaft position sensor was bad according to the scanner so that was replaced, and the scanner is also saying that the oxygen sensor readings are bad. But other than that everything is within specs."

The scan tool will never tell you that sensors are bad. Diagnostic Trouble Codes, (DTC's) will tell you which circuit has malfunctioned, it's the technicians job to diagnose and repair the problem. You mentioned there were no codes.... that is an indication that the PCM has not detected any problems. If there were problems with fuel mixture, oxygen sensors or the crankshaft position sensor, there would be DTC's in memory, and the SES light would be illuminated. With no DTC's in memory and no SES light, the problem is something that the PCM does not monitor such as ignition and fuel delivery.

What is the fuel pressure? Key on, engine off, fuel pump running: Must be 60psi to 66psi and remain above 55psi for 3 to 5 minutes after the pump shuts off.

I didnt perform the re learn I will definitely do that. Also I did forget to mention that the ses light did come on intermitent and that is how we learned that the crankshaft position sensor was bad. Other than that though no ses light has came on for anything else. As far as fuel problem or ignition problem I have had a hankering that that is what it may be too. The fuel pump was replaced a while back because it quit and i suppose that I could have gotten a bad fuel pump. I will recheck the pressure and then go from there. If its not fuel related I will then probably move on to ignition and start with a new cap and rotar. Even if thats not the problem the cap and rotor have 135k miles on em so its definitely not going to hurt anything to change them.

Fuel pumps have been known to go bad prematurely, especially aftermarket pumps. If/when you replace the cap & rotor, don't settle for anything other than AC Delco. Make sure you put a dab of silicone dielectric grease on each terminal, inside and out, of the cap.

Fuel pumps have been known to go bad prematurely, especially aftermarket pumps. If/when you replace the cap & rotor, don't settle for anything other than AC Delco. Make sure you put a dab of silicone dielectric grease on each terminal, inside and out, of the cap.

Will do. When replacing major parts such as cap and rotor, fuel pump, or anything else vital I always use AC Delco. Especially on fuel pumps, anything other than AC Delco doesnt last more than 5 months.

Will do. When replacing major parts such as cap and rotor, fuel pump, or anything else vital I always use AC Delco. Especially on fuel pumps, anything other than AC Delco doesnt last more than 5 months.
AC-DELCO! That is the ONLY WAY to repair these trucks! Don't be fooled by the lower price of the off brand stuff. It WILL ALWAYS COST YOU MORE IN THE LONG RUN!

Update: Did the fuel pressure test and the crankshaft position sensor re learn and the problem is still present. Me and my dad are pretty positive now that it is fuel/air delivery related. We still dont know what though. Checked the MAF sensor and it was clean and appeared to be alright. Could it be a problem with vacuum somewhere possibly? Also when testing fuel pressure took the schrader valve off cuz the tester I have wont fit on it so i have to just screw the tester on to the line instead of the schrader valve. There was a pretty decent amount of black "gunk" inside there. So somehow a bunch of "crap" got past the fuel filter and is now possibly messing up the injectors. I dono how that would even happen but any ideas on how to take care of that potential problem?....short of pulling every injector anyway?

Update: Did the fuel pressure test and the crankshaft position sensor re learn and the problem is still present. Me and my dad are pretty positive now that it is fuel/air delivery related. We still dont know what though. Checked the MAF sensor and it was clean and appeared to be alright. Could it be a problem with vacuum somewhere possibly? Also when testing fuel pressure took the schrader valve off cuz the tester I have wont fit on it so i have to just screw the tester on to the line instead of the schrader valve. There was a pretty decent amount of black "gunk" inside there. So somehow a bunch of "crap" got past the fuel filter and is now possibly messing up the injectors. I dono how that would even happen but any ideas on how to take care of that potential problem?....short of pulling every injector anyway?

It is not impossible that you are seeing remnants of the fuel filter element that has shreded and disintigrated into the fuel line. What is/was your fuel pump pressure when you checked it? How old is your fuel filter? Did you run the prime cycle a few times to clear the fuel line when you had the schrader valve out?

Get back to the basics. Fuel, spark, compression and spark at the right time.

"It would also make an "electrical shocking" type noise in the engine compartment right in front of the drivers side."

Did you look for this? A whole lot of problems can occur without throwing a code.