Cutting out ( shutting down )....

[tricktruk]

Well hell, so we thought we had this thing figured out! Guess again, we thought that the cutting out was due to a failing ignition switch, WELLLLLLL, we replaced the ignition switch, not to hard to do, by the way. And, went to restart the darn thing, wont start. Back to square one. Now I have a certified GM tech telling me that it might be the pick-up coil in the distributor. The engine cranks over fine, plenty of cranking power. As I mentioned before, it starts up when it wants to and may run 5 minutes and cut out, it may run 1 hr. and cut out. it may run 1/2 day then cut out no warning. Sometimes it will restart fine, other times it wont restart for a few days. Heres what weve replaced in the course of fixing this cut-out issue: new mechanical fuel pump, new GM ignition module, new cap-rotor, platinum spark plugs, new ignition wires, new ignition switch. Now I am getting ready to pull the distributor out so we can check its condition. The GM tech is telling me that due to the miles on the Blazer ( 160,000 ) original miles, that the bushings may be worn on the distributor and that the pick-up coil may be failing, or may have sustained damage from the distributor shaft floating around enough to damage the pick-up coil. I am also going to check the ignition coil, by taking some ohm readings to see if it is on its way out. By the way, the ecm ( computer ) is new! Any ideas????
Once again, 1984 Chevy S-10 Blazer 4x4 2.8L V6, carbureted E2SE carb.
Cuts out ( shuts-down ) no warning!

[BlazerLT]

Sounds like something overheating and failing.

Try swapping in a new spark control computer is you can get a loaner from the junkyard or something.

[Michael Powell]

I am a GM tech also, and he is right, it could be wear on the distributor, buuuutttttttttt, I also ran into this problem on a little later model. Check the voltage supply wire to the pick up coil, it could have a break in it that cuts voltage when it is moved. Might help, but I can't fix what I can't see.

[tricktruk]

Originally Posted by Michael Powell

I am a GM tech also, and he is right, it could be wear on the distributor, buuuutttttttttt, I also ran into this problem on a little later model. Check the voltage supply wire to the pick up coil, it could have a break in it that cuts voltage when it is moved. Might help, but I can't fix what I can't see.

Well another day, no go! Today I replaced the ignition pick-up coil, and installed new spark plug wires. Heres what im seeing, I had pulled the distributor to replace the pick-up coil. When I reinstalled the distributor, I had marked the distributor position so I would not throw the timing off too much. There is a four wire pigtail that is usually disconnected to set timing. I started the Blazer up, started immediately. I was ecstatic, I set timing and did some minor idle adjustments on the carb. When I was done with all adjustments, I shut down the truck, checked all vacuum hoses, double checked all my work. I then connected the four wire pigtail connector at the distributor. I then went to restart the truck, and it would not start! I was ready to shoot myself.
The truck was running great while I was making my final adjustments, had not sounded that good in a while. When it would not start, I thought about the last thing I had done before attempting the final start. Well I discovered that when I plug the four wire pigtail connector at the distributor, the truck will not start. I disconnected the plug and it started right up! I tried plugging in the connector while it was running and it dies immediately! My problem at this point is that Im not clear where these wires are coming from or going to. If I run the truck with this plug disconnected, the "CHECK ENGINE" light is on. I pulled trouble codes from computer, as follows" 12, 14, and 24. My truck is a 5 spd, so code 24 should not apply right?

12=No Distributor or RPM Reference Pulse.
14=Coolant Sensor Circuit — High Temperature
24=VSS or Park/Neutral Switch Output Speed Low (4L80E)

Im stumped at this point!

[tricktruk]

Originally Posted by BlazerLT

Sounds like something overheating and failing.

Try swapping in a new spark control computer is you can get a loaner from the junkyard or something.

Are you reffering to the ignition module within the distributor? If so, I just replaced it, also replaced the pick-up coil. If you are reffering to the ECM, it was replaced about two years ago. I may pull distributor again and double check wiring. Question, I found what appears to be a resistor or diode in the distributor, about 1/2 inch square. One leg is grounded, the other lead taps into ignition module wiring. Any ideas as to what that might be? I noticed the wiring coming out of the distributor has been taped. Im going to pull the tape and check for breaks. When I plug in the four wire connector at the distributor the truck dies and will not restart, unplug it, it starts up immediately, but check engine light comes on!!!!!

[BlazerLT]

Could be a bad ECM.

Can you swap a used on in from the junkyard to check?

[tricktruk]

Originally Posted by BlazerLT

Could be a bad ECM.

Can you swap a used on in from the junkyard to check?

Well finally found the culprit behind all my plroblems!
The ECM went out on the blazer. I had unnecessarily replaced the ECM a few years back, involving other issues. After spending a few hundred dollars on unnecessary parts this time around, and not getting anywhere I came to realize that I had the original ECM stored away. I swapped out the ECM in the Blazer with the original ECM and presto!
Problem solved, no more cutting out or stalling. Thanks to everyone for the good pointers and advice! The Blazer is now running better than ever!
Special Thanks to BlazerLT, who led me in the right direction! You were right, THANKS.

[BlazerLT]

SahWEET!

Glad to have helped you.