I have a 1989 s-10 blazer, TBI 4.3L v-6 4x4 228k miles on it. The engine has been running like a champ untill a couple weeks ago. I was driving up a slight incline and its just bogged down and died on me almost like it ran out of gas(3/4 tank full). Imediatly tried to start it up no dice, I waited 30 mins, started back up put it in gear got a block down the road then died again. Got it towed home and found 2 vaccum lines that were cracked the two lines 1 for pcv(dam near cracked in half) and other was to the vacuum pump. I swapped them out, It started up, worked like a champ drove it around the weekend to make sure it was good. Come monday morning go out to start it up and take it to work and wont start. Charged the battery, rechecked the vacuum lines, spark (bright blue at the plug). Plugs, wires, cap rotor all changed in the past year-year and a half. Checked EGR, its not stuck open and bellow does move. I have known good spare parts (came out of running parts blazer) and have swapped ESC module, vacuum pump, map sensor. I have verified injectors are working and spraying fuel correctly (no drips), fuel pump does kick on with key turned on. I havent screwed with the timing but it almost sounds like the timing is off when I try to start it. Ive read the knock sensor can cause timing to jump 20 degrees if this fails or the ESC module fails do to lack of 5 volts sent to the ECM/ECU. This is my baby so maintenance is done as should be and then some, oil change isnt due for another 1k miles. Gonna be doing a compression test this week to rule that out but like I said am stumped any one else run into similar issues?

 

 

 

TBI needs 9-11 PSI. One easy test you can do is pour a small amount of gas directly into the throttle body. If it fires right up and dies shortly you know you have a fuel delivery problem. Clogged fuel filter, or a bad pump or faulty pressure regulator. The one problem with the 89 is that there is not test port for fuel pressure. You will need to install a pressure gage in line with the fuel lines. My daily driver is also an 89 S15 Jimmy 4.3. I installed a permanent fuel pressure gage and an adjustable pressure regulator on my TBI. I bought the gage, adapter fitting and the adjustable regulator from:
CFM Technologies Gm Tbi Performance Products

 

I used to drive a 1989 S10 pickup for about 5 years. Every month or two it would have a "fit" like you describe and leave me sitting on the side of the road for 15 min to an hour. Then would start and all would be normal. It got to the point that I would not panic - just call my wife and tell her I would be late because the S10 did it again. Over the years that I drove it, I replaced all the suspect parts including ECM, injectors, distributor, fuel pump, etc. Finally, determined to fix the damn thing I went to the junk yard and obtained/installed a complete engine wiring harness (the one that goes through the firewall and plugs into the ECM). Never determined the exact problem, but that fixed it.

That said, if you get it into a no-start condition - pull a spark plug and make sure the electrode isn't wet (flooded). Then if injectors are spraying and still no-start, fuel is not the problem. You can forget about it and move on to electrical stuff, which I suspect will end up being your intermittent problem.

Another thing we used to do in the dealership back in the 80s and early 90's was to rap on the ECM case (not too hard mind you) with the engine running. You would be surprised that tapping on the ECM can make the engine die if there is a problem. of course, tap too hard and you create the problem!

Good luck!

 

Thank you for all the responses, I will try starter fluid and see if it starts up. I do have a complete spare harness and ecu bought a running parts blazer(rusted out) exactly for this reason (hoping dont have to do this). I did take off the air cleaner to watch the injectors spray best part about having a TBI, I'm not unfamilar with those have rebuilt quite a few of them. I should have stated there is no service engine soon light staying on (it does work light comes on and goes out with key turn). Will try the paperclip method and see what codes I get if any.

 

When I first bought my 89 s10 Blazer had something very similar. The previous owner put new everything on it trying to fix it but never got it running right. I bought it for cheap because of the running and dying issues. I got it home and did my LT1 swap and pulled the gas tank to put a better fuel pump in and found the line between the pump and pickup tube was split from age I am assuming. We put the 4.3 in a friends s10 and it runs great to this day six years later.

 

Tried using starter fluid into the tbi to see if it would start, no joy. Checked for codes only code that pops is letting me know it's in diagnosis mode ie 12 thats the only flash I get. Gonna check compression this weekend and all plugs hopefully get some insight as to what's wrong. I'm afraid Les is right and might have to swap engine harness.

 

One thing that had me being stuck with my 94 Blazer for a while was the Ignition Module.

Same symptoms that have been described before.

Everything was fine. It would start up like a champ. As long as not warmed up completely it would even re-start.
Once completely warmed up it would run fine. Never let me down on the road but then would not start up again for an hour or so.
Then when cooled down enough it would simply start and run as if nothing were.

May be worth checking if not yet replaced. Could save you the hassle to change the engine harness.

 

Checked compression again sitting between 180-185 on all 6 cylinders. Swapped ICM just to test and no joy, did timing light and is spot on. So thinking harness or ecu. Will swap them out and see how things go, in swapping ecu I need to swap the proms correct?