Help with distributor 95 4.3L

I had to replace the lower intake manifold gasket and as a result removed the distributor. I have a 95 blazer with 4.3L Vortex and a flat top distributor. I know this is a commonly asked question based on the numerous posts I have tried to use as help. I have tried 5 or 6 times and still can't get it to start. After getting to TDC for cylinder #1 on the compression stroke sometimes, I can move the oil pump shaft with the distributor if I pull it up just enough. With everything lined up with the printed #6 still won't start.

As I am somewhat of a novice what should happen if it is installed incorrectly? I turn the ignition and the battery gauge dips and it just and tries to start but nothing, is this typical or is there something else going wrong at the same time.

Another question is that there seems to be conflicting information about how to find TDC, do I line up the first mark on the harmonic balancer or the second mark with the notch?

If the distributor was put in correctly would one expect the engine to start with the upper plenum still removed or does everything need to be put back together for it to start?

Any help is greatly appreciated

I had to replace the lower intake manifold gasket and as a result removed the distributor. I have a 95 blazer with 4.3L Vortex and a flat top distributor. I know this is a commonly asked question based on the numerous posts I have tried to use as help. I have tried 5 or 6 times and still can't get it to start. After getting to TDC for cylinder #1 on the compression stroke sometimes, I can move the oil pump shaft with the distributor if I pull it up just enough. With everything lined up with the printed #6 still won't start.

As I am somewhat of a novice what should happen if it is installed incorrectly? I turn the ignition and the battery gauge dips and it just and tries to start but nothing, is this typical or is there something else going wrong at the same time.

Another question is that there seems to be conflicting information about how to find TDC, do I line up the first mark on the harmonic balancer or the second mark with the notch?

If the distributor was put in correctly would one expect the engine to start with the upper plenum still removed or does everything need to be put back together for it to start?

Any help is greatly appreciated

There is two TDC"s
One compression and one exhaust.

Pull no 1 spark plug and crank engine and stick finger over hole and feel for compression.

When you first feel compression.
Hand turn engine to TDC no 1 pistion.

Pastic straw in spark plug hole will feel TDC.

Or if you want to plull valve cover and check true valve timing.
Your opsite firing cylinder is no 4 on a V6.

The opsite firing cylinder from No 1 cylinder will have a valve rock on 1 TDC compression.

Like one rocker closing and one opening.

Set dist as shown in link.
http://files.automotiveforums.com/gallery/showphoto.php?photo=51302

Let us know how it goes.

Thanks for the quick reply MT.

So I am able to find TDC on the compression stroke and then can line the distributor up as shown in the picture but it still won't start.

I have tried lining up TDC on the compression stroke using both the first and second mark on the harmonic balancer, which one is correct? Some places state the first and others state the second. (I know I could pull the valve cover as you suggested but I am trying to avoid it if I can).

Does the upper plenum and all other connections need to be reassembled in order to start or will the engine start with it still removed?

Side question: If I replaced the lower intake manifold gasket and it is still leaking does this mean I didn't install it correctly or could something else be causing the leak?

Thanks

Thanks for the quick reply MT.

So I am able to find TDC on the compression stroke and then can line the distributor up as shown in the picture but it still won't start.

I have tried lining up TDC on the compression stroke using both the first and second mark on the harmonic balancer, which one is correct? Some places state the first and others state the second. (I know I could pull the valve cover as you suggested but I am trying to avoid it if I can).

Does the upper plenum and all other connections need to be reassembled in order to start or will the engine start with it still removed?

Side question: If I replaced the lower intake manifold gasket and it is still leaking does this mean I didn't install it correctly or could something else be causing the leak?

Thanks

You have to us the mark that you feel tdc compression stroke on.
or just forget the mark and pull valve covers and check it with valve timing.

For the true TDC compression you will have to feel pistion move to TDC on compression stroke, or watch for valve rock on no 4 cylinder.

Do not even try to start with out it all together.

Yes you have to have it all together and everything pluged in and hooked up before trying to start it.

After you find TDC compression set dist rotor to no 6 on dist base.

If you have proper fuel pressure and good spark to all plugs it should start and run.

On the still leaking check it for still leaking first before you try to break it.:lol2:

http://picasaweb.google.com/wilson.p.rupert/DropBox?authkey=Gv1sRgCO7Izrvvicj6Ew#5331738013042 558658
You have to us the mark that you feel tdc compression stroke on.
or just forget the mark and pull valve covers and check it with valve timing.

For the true TDC compression you will have to feel pistion move to TDC on compression stroke, or watch for valve rock on no 4 cylinder.

Do not even try to start with out it all together.

Yes you have to have it all together and everything pluged in and hooked up before trying to start it.

After you find TDC compression set dist rotor to no 6 on dist base.

If you have proper fuel pressure and good spark to all plugs it should start and run.

On the still leaking check it for still leaking first before you try to break it.:lol2:

I reassembled everything and still no luck on getting it started. There is one connector that I can't seem to find where it should plug into and I really hope this isn't what is preventing me from getting started.

The connector looks identical to the IAT sensor plug but I can't seem to find anywhere it would potentially plug into.

UPDATE: the unknown plug is for the coolant temperature sensor down hidden on the front of the engine.

http://i599.photobucket.com/albums/tt80/msfan324/IMG_1462.jpghttp://picasaweb.google.com/wilson.p.rupert/DropBox?authkey=Gv1sRgCO7Izrvvicj6Ew#5331738013042 558658

While you have the air intake off, clean your throttle plate and the bore. It looks a bit dirty...

While you have the air intake off, clean your throttle plate and the bore. It looks a bit dirty...

What is the best method for cleaning it?

Get some sensor-safe cleaner and use a toothbrush and a lint-free cloth to wipe it out.

http://picasaweb.google.com/wilson.p.rupert/DropBox?authkey=Gv1sRgCO7Izrvvicj6Ew#5331738013042 558658


I reassembled everything and still no luck on getting it started. There is one connector that I can't seem to find where it should plug into and I really hope this isn't what is preventing me from getting started.

The connector looks identical to the IAT sensor plug but I can't seem to find anywhere it would potentially plug into.

http://i599.photobucket.com/albums/tt80/msfan324/IMG_1462.jpghttp://picasaweb.google.com/wilson.p.rupert/DropBox?authkey=Gv1sRgCO7Izrvvicj6Ew#5331738013042 558658

There is two there that should be plugged in.

One with pointer looks like Air intake sensor on air intake hose.

Always install air intake hose before starting and plugin all sensors.

Are you getting good spark to plugs and good fuel pressure?
Good Luck

There is two there that should be plugged in.

One with pointer looks like Air intake sensor on air intake hose.

Always install air intake hose before starting and plugin all sensors.

Are you getting good spark to plugs and good fuel pressure?
Good Luck

So if the one I am pointing to is the air intake sensor what is the one to the bottom right of it for then? If I plug either one into the air intake sensor I can't find a location for the other. Kind of baffled buy it.

I need to work on figuring out if I have good spark and good fuel pressure cause I am pretty confident TDC is correct but it still wont fire up.

Yes

I tested with a multimeter and I know I have power at the coil and at the coil wire before plugging into the distributor. When testing for actual spark at the plugs I pulled both cylinder #1 and cylinder #4 and there was no spark when trying to crank the engine. Does this mean I should invest in a new cap and rotor to fix the problem?

Without getting a fuel pressure gauge its anyones guess if thats good but I don't see how it could have changed when it worked before I replaced the gaskets. When I have the upper plenum off and I hand crank the engine to find TDC I can smell fuel if thats worth anything. In addition while cranking the engine I could smell gas coming from the cylinders I removed the plugs from.

For the mystery plug if one is the air sensor then what could the other one be for? One is marked PED 68 and the other is marked PED 16* where as the one that plugs into the EGR valve is marked PED 2.

For testing for spark if no spark to spark plugs check foor spark at coil plug wire tower.

Make sure the crank sensor wiring and plugin is good and pluged in good.

If crank sensor and coil and PCM and wiring and everything pluged in good is good the coil should spark at coil wire tower.

For testing for spark if no spark to spark plugs check foor spark at coil plug wire tower.

Make sure the crank sensor wiring and plugin is good and pluged in good.

If crank sensor and coil and PCM and wiring and everything pluged in good is good the coil should spark at coil wire tower.

MT,

I am unclear on what you mean by the coil plug wire tower, could you please explain? The crank sensor is what plugs into the distributor itself, correct? What does PCM stand for? I should mention the points inside the cap are very dark and corroded so it probably is a good idea to replace it regardless.

Coil tower is where the coil wire comes out of it.

Crank sensor on flat top dist is down on front of engine beside front crak damper.

Coil tower is where the coil wire comes out of it.

Crank sensor on flat top dist is down on front of engine beside front crak damper.

I replaced the cap and rotor and still no spark at the plugs. I am testing for spark by removing a spark plug, connecting the plug wire to it, then holding the threads of the plug against a part of the engine and looking for spark while the engine is cranked.

When turning the key to the on position and checking at the location where the ignition coil wire connects to the coil before connecting to the distributor cap I get 9V (if I am measuring it correctly). Also if I plug the wire into the ignition coil and test at the end of the wire before it plugs into the distributor I get the same reading. The crank sensor is pluged in securely and see nothing suspicious about it.

Any suggestions on what I should be testing to narrow this down to a culprit?

Check for good hot blue spark from coil tower.

Does fuel pump hold good pressure while cranking?
Does it have injector pulse when cranking?

Is the VCM/PCM getting a good rpm signal cranking engine?
You can not tell just by looking at crank sensor.
Test and check crankshaft sensor.

Also there is a dist module mounted on coil bracket.
See if your parts place can test coil and dist module for you.

Also there is a dist module mounted on coil bracket.
See if your parts place can test coil and dist module for you.

So I finally gave up and towed it to a shop to have it looked at. They say that why it wont start is because the computer is bad and it needs a new battery. How could you self diagnose a bad computer or could the PCM be taken to autozone and tested? What shouldn't work if the computer is bad? What could have caused the damage?

As for the coolant leak it is coming from one of the freeze plugs at the back of the engine. Any hope of replacing this myself?

So I finally gave up and towed it to a shop to have it looked at. They say that why it wont start is because the computer is bad and it needs a new battery. How could you self diagnose a bad computer or could the PCM be taken to autozone and tested? What shouldn't work if the computer is bad? What could have caused the damage?

As for the coolant leak it is coming from one of the freeze plugs at the back of the engine. Any hope of replacing this myself?

What test or codes did they run to decide bad computer?
Or why did they decide bad computer?
AZ can not test computers.
And bad computers do not set many codes for bad PCM.

To check for bad computer younneed a engine cpable scanner and watch what inputs and outputs the computer has.

What test or codes did they run to decide bad computer?
Or why did they decide bad computer?
AZ can not test computers.
And bad computers do not set many codes for bad PCM.

To check for bad computer younneed a engine cpable scanner and watch what inputs and outputs the computer has.

Not sure about exactly what test or codes that lead them to decide it was bad. They said they weren't able to get any signals from it so sounds like they couldn't run any tests on it.

Just curious: To clarify the PCM is the black box that is under the hood above the shock tower on the passenger side. Is there a separate piece of hardware that handles the error codes?

What other than possible a bad jump start could hurt a computer?

I figure maybe I can get it back running and then have the freeze plugs replaced by a shop but I want to keep from doing whatever it was the first time to damage the current computer.

We would need to know what the problem is to help you.
But remember.
Computers have eletrical circuit boards resistere and diodes and other stuff.
Low or high or spike voltage and bad grounds and moisture or even tempt shock can wipe them out.
Just like females Treat them with tender loving care.

Just an update:

I got the blazer looked at again by a mobile mechanic. The krux of the problem is that there is no signal from the computer at all. When hooking up the scanner no information shows up for any of the sensors or the brake system. There is good power at the coil and going to the distributor just no signal. Because the guy was a technician at a Chevy dealership for 14 years I found out the computer is an outdated version and possibly after setting with the battery unhooked for three weeks may have done it in. So I have ordered a new computer in hopes of fixing my problem.

Just an update:

I got the blazer looked at again by a mobile mechanic. The krux of the problem is that there is no signal from the computer at all. When hooking up the scanner no information shows up for any of the sensors or the brake system. There is good power at the coil and going to the distributor just no signal. Because the guy was a technician at a Chevy dealership for 14 years I found out the computer is an outdated version and possibly after setting with the battery unhooked for three weeks may have done it in. So I have ordered a new computer in hopes of fixing my problem.

Very seldom it is a bad computer.
Let us know how it goes.

Very seldom it is a bad computer.
Let us know how it goes.

I know, it was a sort of a last resort but since two different diagnois came to the same conclusion.

In regards to a passlock relearn, what is the security light that comes on? Is this an actual indicator on the dash or some other light?

For security light look on dash when ign is first turned on.

If it has one it should come on and then go off if all is well with it.

Well that would explain why I can't find it or have never seen it cause I am pretty sure I don't have one. Doesn't even mention it in the owners manual.

So I got the new computer earlier this week, installed it and still no start. It does make a bit of a thumping noise when I start it and try to give it some gas but other than that not much different.

Can you remove the distributor cap and verify that the rotor is going around when cranked? and/or does it have oil presure when cranked.

I have not confirmed yet if the distributor rotor moves but I know during the numerous times I was trying to reinstall that when I cranked the engine by hand it would rotate. As for oil pressure I only have what the dash board guage tells me.

Is there anyway there is some kind of ground wire on the back of the engine or somewhere that got messed up when I replaced the intake manifold gasket? I am starting to suspect it isn't the PCM that is bad but some kind of wiring thing. What connector and pins would I need to check for good ground on the PCM. What would I need to check for to make sure I am getting the signal to actually get some spark. My computer is under the hood above the passenger shock tower.

I have not confirmed yet if the distributor rotor moves but I know during the numerous times I was trying to reinstall that when I cranked the engine by hand it would rotate. As for oil pressure I only have what the dash board guage tells me.

Is there anyway there is some kind of ground wire on the back of the engine or somewhere that got messed up when I replaced the intake manifold gasket? I am starting to suspect it isn't the PCM that is bad but some kind of wiring thing. What connector and pins would I need to check for good ground on the PCM. What would I need to check for to make sure I am getting the signal to actually get some spark. My computer is under the hood above the passenger shock tower.

A good repair manual has a pin out test you can do on the VCM/PCM for ground and power to it.
Or a all data online sub.
http://www.alldata.com/products/diy/index.html

Also check for codes and scanner readings for problems.
Post back any codes.

I am unable to get any codes even with the new PCM installed as the scanner still cannot communicate with it. So I'm thinking its not the PCM that is bad. Is there any way to manually get codes that might be set without using a scanner? (I now understand this only works for OBD1 not OBDII)

Does everything else work on this vehicle when the key is turned to "on"?

fuel pump, radio,lights, blower , ect.

Does everything else work on this vehicle when the key is turned to "on"?

fuel pump, radio,lights, blower , ect.

Yes, I can hear the fuel pump, radio works, lights turn on, I can charge my ipod with the cigarette lighter.

I think maybe I have been approaching this wrong and should try to find out why I don't get any spark instead of just focusing in on a scanner not getting codes. But now that I have replaced the computer I am pretty confident it isn't the PCM that is bad since both the old and new one result in the same no start condition. Something else somewhere is messed up.

I went back to beginning of thread again to see things in order. It sure does seem like it is a key on or ignition problem. Key on to pcm should bring up live data to a scanner and read any codes (there or not) and also power up the distributor/coil.

I am still baffled why changing lower intake manifold gaskets would cause that kind of issue. Is there any way to check the ignition switch to completely confirm that is where the problem lies?

I finally got it to start today. After having someone come out to look at it last night he made a few comments about remembering all the connectors I unplugged and plugged in. I remembered that I had a very hard time plugging in the crankshaft sensor but didn't think much of it at the time. I pulled the connector today and found that one of the pins in the sensor was bent up against the side. I straightened the pin, plugged in the connector, and it finally started up! I then put the old computer back in and it still starts. This explains why I had no spark and why a scanner couldn't pull any codes. And to think all of this was caused by a silly little metal pin. I learned from this that even though a scanner couldn't pull codes didn't mean that the computer was shot but instead a more in depth investigation should have been made into finding out why there wasn't any spark since. I can't imagine how much this would have cost to fix at a shop since they wanted to charge me $400 plus to replace the computer and then it still wouldn't have even started. Thanks to everyone for their help along the way.

I finally got it to start today. After having someone come out to look at it last night he made a few comments about remembering all the connectors I unplugged and plugged in. I remembered that I had a very hard time plugging in the crankshaft sensor but didn't think much of it at the time. I pulled the connector today and found that one of the pins in the sensor was bent up against the side. I straightened the pin, plugged in the connector, and it finally started up! I then put the old computer back in and it still starts. This explains why I had no spark and why a scanner couldn't pull any codes. And to think all of this was caused by a silly little metal pin. I learned from this that even though a scanner couldn't pull codes didn't mean that the computer was shot but instead a more in depth investigation should have been made into finding out why there wasn't any spark since. I can't imagine how much this would have cost to fix at a shop since they wanted to charge me $400 plus to replace the computer and then it still wouldn't have even started. Thanks to everyone for their help along the way.

Thanks for posting back the fix and how it went.
That will do it every time.:rofl: