Bought Blazer 6 months ago
had to replace fuel pump and filter
just recently running badly
cleaned mass air flow sensor
changed crankshaft position sensor
changed air filter, cap and router
seemed to help but went for a test drive
and then it stopped running
now car isn't running at all
problems are
battery light comes on off and on during drive
black smoke from tail pipe
and loss of power and hesitation when it was working

 

Any Check Engine/Service Engine Soon light? DO you have a scan tool or code reader?

The battery light could be related, and I'd have the battery tested first. Low voltage from the battery can cause lots of issues. If the battery is good, check the serpentine belt and tensioner, and the alternator.

Black smoke = rich mixture.

You might have leaking injector(s). Leaking fuel pressure regulator.

Will it start for a few seconds with staring fluid? Squirt some in the PCV fitting on the intake pipe.

Will it start and cough for a bit with the fuel pump relay pulled out? If it's flooding from leaks in the manifold, sometimes it will cough and try to start with no fuel pressure as the excessive fuel in the manifold evaporates. There's a few seconds where the mixture is close enough to optimum where it will run.

Is it "making oil"? Check the oil. If there's more in there than you think there should be, and if it smells like gasoline, you have a fuel leak inside the intake.

 

brand new alternator changed about a month ago
the battery has been checked and it's fully charged
car was rough starting and sometimes would shut off during idle so I changed the distributor cap and roter and then it ran okay during test drive but as I was coming back the car just stalled and then wouldn't come back on the engine keeps turning but that's it had to have a friend tow my car back to my house

 

Actually, the first test is to figure out if you have spark. Pull #1 plug, place it on grounded metal, with the plug wire attached, and watch it while an assistant cranks the thing on the starter. If you have no spark, that's a different set of diagnositcs. If there is spark, pay attention to the tests and checks I posted before about fuel related issues.

A fuel pressure and leak down test would also be in order. Check pressure at the test port during/immediately after priming, and 10 minutes later with the thing shut off. During prime, pressure must be 60-66psi. 10 minutes later, it must be over 50psi.

Testing pressure at the fuel filter the same way would also be helpful, especially if it's leaking down. That test runs the pump into the gauge instead of into the injector/engine. Pressure should be higher there, IIRC, 70+psi at prime, and >65psi after 10 minutes.

The quick checks I mentioned before can be performed without a pressure gauge and will give clues as to where the problem is.

 

Thank you I will try all that this evening after work. I have gotten several people telling me it may be the MAP sensor...do you know anything about this?

 

If you truly changed the CRANKshaft position sensor on the front of the engine, did you perform the relearn procedure? This needs to be done with a capable scan tool.

If you changed the CAMshaft position sensor on the dizzy, no relearn is necessary.

Hope that helps a little...

 

hmmm no I don't think I did the relearn procedure sorry I'm not very good with cars obviously LOL I reset the computer and not sure if that made it worse or what??? Any help or suggestions would be greatly appreciated

 

Was it running and starting before you reset the computer? Did the "no start" situation come about immediately after you "reset the computer"?

I'm assuming here that "reset the computer" = disconnected the battery for several minutes, or did you do some other "reset" procedure?

Why did you think it was necessary (or just a good idea) to "reset the computer"? Was there a SES light/CEL before? Did you get the codes read with a scan tool/code reader.

The very first step of any diagnosis is to read the DTC's with a scan tool/code reader. Often there's information that will tell you what's wrong (or more accurately, what the computer thinks is wrong). "Resetting the computer" can eliminate important information and make fixing it much harder.

With regard to alternator light coming on and alternator/battery, get everything tested (again, after the light started acting flakey). If both the alternator and the battery are good, and your battery light is coming on, it's a belt/tensioner issue, or there's a wiring harness problem, or maybe something flakey with the PCM.

As far as CASE relearn (crank angle sensor error), if there's a P1336 DTC stored, you'll definitely have to do the CASE relearn. If there are other DTCs present, you have to fix those before you can successfully complete a CASE relearn. Having said that, I've never seen an engine that was running (with misfires maybe) with a failing/old crank position sensor fail to start after the bad/old crank position sensor was replaced with a new one. Even an engine that died because the CKP totally failed will almost always start with a new sensor installed. It might not run optimally, and it might not even run "good enough", but I've never seen one not start with a new sensor. The CASE relearn procedure requires that the engine must start and run at specific speeds during the relearn procedure. If it won't start, you can't even do a CASE relearn.

 

Im having a no start issue with my 96 4.3L vortec. It looks like there's a lot more oil then there was when i checked it and the oil seems thin. So when you say it could be fuel leaking in the intake that would mean it's my fuel injectors?? Or can you explain a little more. Im a female and I've done a lot of work, on my truck but still learning as well . thanks