I know a lot of people have posted on similar problems.
I have looked through several dozen of them and tried many suggestions with no luck.

I have a 1999 Chevy Blazer 4x4 with a 4.3 engine. (Wife's truck) The truck starting missing but was still reasonably drivable. Last week she called me from work, she was having a hard time getting it started and was afraid that it would not make it home because it was running crappy.
That night I replaced the Plugs, Wires, Dist Cap, and Rotor when I started the truck it was running
even worse. I rechecked all the wires several times even against 2 different books and they are connected properly, I then cleaned the old cap and put it back on to verify the new cap, no change. I even put the old wires back in to check them, no change, I know the 4.3 prefers AC Delco plugs I pulled out champion 3013 plugs and replaced them with the same.
OK summary time.

I have replaced the Plugs, Wires, Cap, Rotor, Cam Shaft Position sensor (Stator Pickup) and coil.
I test the voltages at the crank shaft position sensor ( tested ok) also pulled the sensor to check for any material on it (none). Ran a pressure check on the fuel system (results were 53 psi). Also
did a bleed down test for the injectors ( took over 2 hrs to bleed down to 50 psi and is still at 50 psi this morning, 14 hrs later). I am not sure where to go now it is getting expensive. I try to start it and it tries to fire, sometimes back fires, sometimes starts but running really bad (P0300) multiple cyl misfire and dies. Any thoughts on whether I should replace the Ignition control module, Crank shaft sensor or the ECM or any other
avenue to look at.

totally fustrated

Thank you

 

Have you cleaned the EGR valve and MAF sensor yet? Those would have been two of the first things to do...

 

yes I checked and cleaned both.

 

Well ok then. Lets start with you telling us everything that you have done to try to fix the issue (all those threads you read and tried without success). Do not leave a detail out.

 

The truck starting missing but was still reasonably drivable. Last week she called me from work, she was having a hard time getting it started and was afraid that it would not make it home because it was running crappy. That night I replaced the Plugs, Wires, Dist Cap, and Rotor when I started the truck it was running even worse. I rechecked all the wires several times even against 2 different books and they are connected properly, I then cleaned the old cap and put it back on to verify the new cap, no change. I even put the old wires back in to check them, no change, I know the 4.3 prefers AC Delco plugs I pulled out champion 3013 plugs and replaced them with the same.

I have replaced the Plugs, Wires, Cap, Rotor, Cam Shaft Position sensor (Stator Pickup) and coil.
I test the voltages at the crank shaft position sensor ( tested ok) also pulled the sensor to check for any material on it (none). Ran a pressure check on the fuel system (results were 53 psi). I did a bleed down test for the injectors ( took over 2 hrs to bleed down to 50 psi and was still at 50 psi 14 hrs later). Cleaned the EGR valve and MAF sensor. I try to start it and it tries to fire, sometimes back fires, sometimes starts but runs really bad and dies. Get DTC (P0300) multiple cylinder misfire. Also I had to pull the new plugs and clean them, they were all completely covered with black Carbon except for cylinder # 2
.

 

I am looking at replacing the Ignition control module or the Crank position sensor.
Would I be getting spark if the crank position sensor was bad? Also does replacing either
of these make sense with the information above.

 

Well I replaced the Ignition Control Module with no luck. Also when I try to start the
truck there is a strong smell of gas and it strains the starter at some points as if the cylinder was firing at the wrong time. recheck the timing with Cylinder no 1 at TDC
the rotor correctly points to # 1 (arrow on inside of distributor). Need help desperatly
This is my wifes truck and we cannot afford to replace it.

Is this the proper location to post this, I don't seem to be getting much response.

Thank you

 

Are you sure that the distributor is not 180 degrees out? There are two marks on the balancer 180 degrees apart. Did you follow the timing procedure posted in the DIY section?

And I think this is as good a place for this post as any. Might get more looks in the 2nd gen tech section, but maybe not... I can move it if you like, but it is the holidays and I am sure that many people are quite busy right now. I know I have been.

 

I have check the the distrubutor against the number one cylinder. Verified it was on compression stroke
with a compression gauge and then moved the engine slightly CW and CCW with a feeler in the number one cylinder
spark plug hole toverify it was at the top of it's compression stroke when the distributor was at # 1.
I will take a look at their timing procedure, but the 1999 4.3 does not have adjustable timing.
Also the distributor has never been removed from the engine. The truck started running really bad (missing)
when my wife was driving it on the highway.

Yes it is that time of year, Thank you.

 

Well I went way out on a limb and replaced the fuel pump because the pressure was marginal also the sending unit was bad.
Eventually managed to get the truck running, it is still missing really bad DTC PO300. Ya this is getting expnsive.