1984 S-10 Blazer cutting out.....

Ok, here we go! Ive got a 1984 S-10 Blazer 4x4 5 spd. with 2.8L V6. The truck was garaged for about 4yrs. I recently got it back on the road.
The truck has been running fine for about 3 months, now it has developed a stalling condition. It will sometimes fire up first try, run fine for a while. When you least expect it, it cuts out. The last few times it cut out, no warning. Sometimes it will restart right away, other times it wont restart at all. The first time it happened we thought the gas guage was reading wrong, so we poured gas down the carb, and it started right away. We drove it to a station and filled it up to eliminate the low fuel issue. Right after filling it up we got about a block away and it cut out again, and would not restart. The tow truck driver told us that it sounded like the fuel pump went out. I replaced the pump a couple days later, went to fire it up after replacing fuel pump. It started right up, while I put the tools away and got ready for a test run, it cut out while it was warming up at fast idle. I spoke to another mechanic that said, due to miles on the truck 168,000...that the ignition module could be failing. Replaced that, had trouble restarting. Found a bad ignition wire from the coil to the distributor. Decided to do tune-up, cap, rotor, platinum plugs, new ignition wires but only replaced coil wire for now, for restart. Fired up great, then cut out after warm up. Would not restart. Sometimes will restart after cutting out, other times will not restart til next day. Sometimes runs for quite a distance, other times only runs for a couple blocks! Im stumped, mechanic told me that fuel tank has a strainer on fuel pick-up that might be clogged. I dont think its a fuel problem due to sudden cut out. I would imagine if it was a fuel delivery problem, that it would gradually run out of fuel and slowly drop off power, and stall. when it cuts out, its as if you turned off the ignition! The ignition spark looks fine at the plug end of the wires. Stumped in Cali. :banghead:

is your truck throttle body injected or does it have an electronic feedback carb on it?

Ok, here we go! Ive got a 1984 S-10 Blazer 4x4 5 spd. with 2.8L V6. The truck was garaged for about 4yrs. I recently got it back on the road.
The truck has been running fine for about 3 months, now it has developed a stalling condition. It will sometimes fire up first try, run fine for a while. When you least expect it, it cuts out. The last few times it cut out, no warning. Sometimes it will restart right away, other times it wont restart at all. The first time it happened we thought the gas guage was reading wrong, so we poured gas down the carb, and it started right away. We drove it to a station and filled it up to eliminate the low fuel issue. Right after filling it up we got about a block away and it cut out again, and would not restart. The tow truck driver told us that it sounded like the fuel pump went out. I replaced the pump a couple days later, went to fire it up after replacing fuel pump. It started right up, while I put the tools away and got ready for a test run, it cut out while it was warming up at fast idle. I spoke to another mechanic that said, due to miles on the truck 168,000...that the ignition module could be failing. Replaced that, had trouble restarting. Found a bad ignition wire from the coil to the distributor. Decided to do tune-up, cap, rotor, platinum plugs, new ignition wires but only replaced coil wire for now, for restart. Fired up great, then cut out after warm up. Would not restart. Sometimes will restart after cutting out, other times will not restart til next day. Sometimes runs for quite a distance, other times only runs for a couple blocks! Im stumped, mechanic told me that fuel tank has a strainer on fuel pick-up that might be clogged. I dont think its a fuel problem due to sudden cut out. I would imagine if it was a fuel delivery problem, that it would gradually run out of fuel and slowly drop off power, and stall. when it cuts out, its as if you turned off the ignition! The ignition spark looks fine at the plug end of the wires. Stumped in Cali. :banghead:
Back again, well I figured it out, after spending countless hours on this forum, checking anything to do wit S-10 p/u, S-10 Blazers, I could not help but notice that the ignition switch was mentioned in quite alot of posts! So, heres what I did, I was lucky enough that my Blazer was in a STARTING mood. I fired it up, let it get to running temp, carefully, while engine is running, wiggle the key in the ignition switch, careful NOT to crank engine while already running, NOT good for starter or flywheel ring-gear. Truck was idling at around 1200 r.p.m., everything fine til I moved key around, then it died immediately. Would not restart after that. Im heading out to buy a new ignition switch, hope install is NOT to bad. My guess would be worn contacts in switch, will let everyone know end results! :naughty:

Idle is 1200rpms?

is your truck throttle body injected or does it have an electronic feedback carb on it?



My truck is carbureted with E2SE feedback carb! These carbs are a pain in the tail, nothing but trouble with choke operating properly. Now we cant seem to get low idle down where it should be.

Idle is 1200rpms?

Yup, cant seem to get idle down to where it should be, which would be 800 rpm. Right now idle is floating between 1100 and 1200 rpm, at low idle. At start-up, or high idle, it is idling at 2000 rpm. I am in the process of making adjustments to the carb so we can get things were they should be! :eek7:

Best to check your timing as well.

Could be way advanced causing the high idle.

Best to check your timing as well.

Could be way advanced causing the high idle.

:mad: O.K. heres what Ive done trying to remedy the cutting out issue.
I replaced: mechanical fuel pump, ignition module, complete tune-up including cap, rotor, platinum plugs, new ignition wires. Also, pick-up coil, ignition switch, which by the way, I thought the ignition switch was the culprit, because if you touched the key while truck was running, very light touch, it would cause the engine to shut down. Well that wasnt it!!!!!
Now I have dscovered that while setting timing, with four wire plug disconnected at the distributor, truck starts up fine and runs good. As soon as I connect the four wire plug back up it will not run or start at all.
Any ideas? A certified Gm mechanic says that it sounds like the ESC is going out or is fried! The ECM seems to be working fine, no codes pertaining to ESC at all. Had a code for coolant sensor, and code 12, no pulse signal to ECM. I do NOT know where the ESC is located. Im told that the ESC controls spark, and timing?
1984 Chevy S-10 Blazer 4x4, 5spd. carbureted, E2SE feedback carb,
2.8L V6. Im stumped! :screwy:

Have you checked the timing when it was running?

Ok lets start off with the high idle. you have a coolant code well belive it or not but that is your high idle problem. When the coolant sensor goes bad on your truck it tell the computer that it is -20 deg and it needs lots of fuel so the idle stays up. I would fix that problem before you mess with anything else. You stalling problem might be connected with it.
As far as the esc driver that is built into the ecm and the only way to change it is to install a new ecm, both of these problems are very comon on that year.

Ok lets start off with the high idle. you have a coolant code well belive it or not but that is your high idle problem. When the coolant sensor goes bad on your truck it tell the computer that it is -20 deg and it needs lots of fuel so the idle stays up. I would fix that problem before you mess with anything else. You stalling problem might be connected with it.
As far as the esc driver that is built into the ecm and the only way to change it is to install a new ecm, both of these problems are very comon on that year.

Shouldn't we check what the temperature sensor is sending to the ecm before it is replaced.

Without seeing if it is sending the right signal, we might be replacing a good sender.

Have you checked the timing when it was running?


:confused: Yes, set timing and checked it while running with four wire pigtail disconnected. Timing is set at 10 degrees BTDC as per specs.
@ 950 rpm. Timing is rock solid at 10 degrees. I just realized that I have the original ECM stored somewhere, will swap it out with the one in the truck and see what happens. Question, would a bad eprom chip within the ECM cause the complete ECM to fail? Thinking maybe my chip is bad.
My other question would be, if the ECM was bad, I wouldnt be getting any codes at all right? It does go into diagnostic mode, which would lead me to believe that it is working? :sly:

Ok lets start off with the high idle. you have a coolant code well belive it or not but that is your high idle problem. When the coolant sensor goes bad on your truck it tell the computer that it is -20 deg and it needs lots of fuel so the idle stays up. I would fix that problem before you mess with anything else. You stalling problem might be connected with it.
As far as the esc driver that is built into the ecm and the only way to change it is to install a new ecm, both of these problems are very comon on that year.


High idle problem has been solved, dealer adjusted idle mixture screw. I found it practically falling out of the carb base plate. Luckily, I have the flex tool to adjust the mixture needle. Reset it where it should be, idle is perfect @950 rpm to spec.
The coolant sensor issue was caused by me, while I was adjusting idle mixture needle, the sensor was in the way, I removed it and plugged off the sensor opening on the manifold. I was adjusting the idle mixture, engine running with the coolant sensor removed, thats why the code popped up! Cleared ECM memory, fine now!

Excellent, enjoy your truck. :)

Good keep on trucking.

Find out for sure that it is your ignition system so that you will have a narrower problem search. Drive around with an inductive timeing light hooked onto the center wire of the distributer with the timing light sitting on your dash, wires running in passenger door and wires carfully run out of closed hood. When the S10 starts to cut out, squeze the Trigger on the timing light. If it is flashing solid, it's not your ignition. but if it stops flashing or flashing once in a while, it is definatly the ignition system. >KP

Excellent, enjoy your truck. :)
Well ,not quite done yet! The Blazer is running pretty good right now but I cant connect the four wire pigtail at the distributor! This plug is to be disconnected to set the timing. Once I was done setting the timing, I reconnected it but it wont start up. As long as I disconnect the plug, it will start up like a champ, and run pretty good but As long as that plug is disconnected, the ECM is not able to make adjustments! So, im sure im not getting any spark advance or fuel mixture adjustments from the feedback carb. Ive been told that it sounds like the ECM is bad, but, I am able to get it into diag mode. I figure if the ECM was "dead", that it would be completely shut down right?

Don't disconnect it there for timing, you disconnect the one timing wire inside of the cab.

http://img.s10forum.com/album2091/aab.sized.jpg

See it there.

Good keep on trucking.


:smokin: 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 spare ECM and presto!
Problem solved, no more cutting out or stalling. The Blazer is now running better than ever! Thanks to everyone for the good pointers and advice! :)