Sister has a 92 Blazer W. A week ago she called me and said it started having a slight hesitation. A couple days ago the slight hesitation turned into stalling. She says it will stall at any time, warm, cold, idle, driving, accelerating, braking, cruising, etc. I had her hubby read fuel pressure, thats good. He said when it stalls you can smell raw gas in the exhaust. When running good it has no odor. I suggested a full tune up, he said that was first thing he tried. I said its prolly the coil or ign mod. He said he was told by a guy at work it may be the ign module, so he changed that when he did the tune up. I said check the coil. He said when he checked it on the meter, it read good, but the car usually runs good. He is a pretty good parts swapper. The only other thing I can think of would be the pickup coil or ign coil. Or maybe wiring. With them getting unburned fuel out of the exhaust it leads me to believe its an ign problem. Does anyone else have any ideas or hints for someone with limited tools I can help over the phone?

Hard to fix one over the phone.
Proper testing first.
Does it lose spark or fuel pressure when it quits?
What are the fuel pressure reading and what does the pressure do when it quits.

If it is just losing spark and you want to throw parts at it.
IGN module and pick up coil and reg coil and wire is things to start with.
Also a tap test on the PCM.
Good Luck

I hear ya on that one. Hard to fix over phone. Does not lose fuel pressure. Fuel pressure hits 65 at prime, holds about 60 for at least 5 min, idle is 58-60. Same readings as when she bought it and I checked it out 4 years ago. When it stumbles or dies pressure stays. She may be able to get it here over the weekend, if she isn't afraid to drive it. As I said, he changed out the ign module with no change. He may just change coil and pickup coil. His choice. Pickup coil was $10 and coil was $25. I said go ahead, your money, but I doubt it's both.

If it has the computer in glove box are be sure to give it the tap twist test if all else fails.
Let us know how it goes.
Good luck

He stopped by today with the coil. I took a spare from my shelf in the garage and ohmed them both out. The one he brought over had green in the 12v and ground plug. The readings on one winding was close, but the other winding was not. I cant remember what one was the primary winding and what was the secondary winding. He assumed the coil was good because it was not showing open on the meter. I gave him my spare coil for now, so we will see how it goes. Does anyone have the specs on the coil to check it, I'm just curious if it is out of spec and if so how far. I'm sure I could look it up, but this gives me a reason to be here ;)

So, the car was brought over. It is sitting in the garage now. List of new parts.
Plugs
Wires (old ones had lots of resistance.)
Dist. Cap.
Rotor.
Pickup Coil (insulation on wires was cracked)
Ign Module
Ign Coil (one on it had lots of green in the plug receptical)

When base timing was set, I noticed coolant on the EST wire, and found the heater core had a small leak. Carpet wasn't even wet. So, I replaced that. While I had that apart I checked the wires from the dist to the ecm. All were good while tugging, shaking, etc. Twist and tap does nothing, when it acts up, it acts up. This car was run about 18 months ago with a bad O2 sensor, so I will check back pressure tomorrow. Most times it is fine and will light up the tires though, so I'm not holding my breath on that one. I did notice when it acts up the cat smells though, so maybe.
Fuel pressure reads 65 at prime, holds at 60 for quite a while, idles at 58-60. It seems to get a bit higher when it is acting up though. I would think if it were leaking fuel in the intake anywhere (nut kit or regulator) it would be constant, but it is only when it wants to. TPS reads (engine off) .375v at idle, 4.35 WOT. MOD says it should be under 1v at idle and about 5v at WOT. Same thing, tap, twist, etc, no change. Will start but immediately die with MAP unplugged. IAC was cleaned with no change. Anyone have any ideas on this one? I kinda wish it would just break and not run anymore so I could track it down.

My '93 Bravada had intermittent issues that eventually turned into constant issues. Turned out to be the fuel pressure regulator was leaking, but not all the time (at the start). This gave me a smell from the tailpipe.

Easy way to check is to pull the Vortec cover, then pull the IMTV underneath to look into the plenum with a flashlight. Generally, you can see if the FPR is leaking. You might not have puddles, but washed (clean) areas will be easy to spot. Just be careful when you pull the IMTV. You might have to spray a little WD40 or the like around the outside, then gently twist back and forth until it comes loose and you can remove it. There's an o-ring on it you need intact to reinstall - and when you do, lightly coat it with engine oil.

I think it's 2 T-30 screws to remove the Vortec cover, then 2 T-25 (I think - they might be T-20) screws to pull the IMTV. Plus the electrical connector, of course.

Also, has the EGR valve been checked? It's possible it has some carbon buildup or chunks that are sticking open the pintle. Mine had huge chunks after I replaced the FPR, but that was due to the excess fuel being dumped into the cylinders.

Easy way to check is to pull the Vortec cover, then pull the IMTV underneath to look into the plenum with a flashlight.
Was checked already and looked no different then the other side. Mitchel on Demand calls this the 'Varible Tuning Control Motor.'

Also, has the EGR valve been checked? It's possible it has some carbon buildup or chunks that are sticking open the pintle.
One of the first things that was checked. Also has the gasket with the screen.

Update. She couldn't wait so she brought it to a shop. They were convinced it was the injector. So, they replaced it. New injector and nut kit, a few hundred bucks later and no difference. Fuel pressure is up to spec and holds. list of new and verified good parts.
Plugs (AC Delco) Was due for tune up.
Wires (AC Delco) Was due for tune up.
Dist cap (AC Delco) Was due for tune up.
Rotor (AC Delco) Was due for tune up.
Ign. Coil (AC Delco) I had spare in garage
PIckup coil (AC Delco) Had cracks in wires.
Ign. Module (AC Delco) Tried on a whim.
Nut kit (AC Delco) Shop said it was problem
Injector (AC Delco) Shop said it was problem

These parts were all checked as within spec, and verified with other known working parts.
Egr was removed and cleaned, reads correct with scan tool. Screened gasket was used.
TPS was checked, was replaced with a known good one, no change.
MAP was checked, was replaced with a known good one, no change.
IAC was checked, was replaced with a known good one, no change.
VTCM, or IMTV (depending on where you look) was replaced with a known good one, no change.

Engine is sound mechanically. Good compression in all cylinders.

All wires to dist were checked and checked good. ECM wires were checked and checked good. Dist has no play or slop.
Now, to be honest, when she took it and brought it to shop, I was done with it. But, it is my sister and I don't want to see the shop soak her. The only other thing I can think of would be the ECM, but I do not have a spare to swap/test with. I am open to any suggestions.

Has the crankshaft sensor been tested?

I was not aware this engine had a Crank sensor on it. Where would it be located? I cannot find one for sale at any parts stores or in the wiring diagram from MOD 5.

No crank sensor on 92 old style ign.
Make sure all wiring and plug ins are good
The computer on them years will do things like that.
The circuit board gets a crack or lose solder joint.
Only test I know of for them is the old tap and twist test.
Do it cold and warmed up and half warm.
If engine running changes on tap or twist test you have found the problem.
You can get a rebuilt one less than 100$.
Or pick up one at salvage yard for a spare or testing.
Good Luck

Have you ever checked the battery cables? My negative went bad and I would have never found it unless a friend was standing outside and just happened to touch while we were working on it and found that the end connected to the battery was very warm and if he moved it around he could get the engine to shut off. Obviously, cutting off electricity to the motor. Easy $10 fix with the negative cable. Might be worth a check. Also, check the ignition switch.

A couple of days ago I had him pull the ECM and use CRC Electrical Cleaner on the ECM and plugs. It had no change. Sunday night he pulled the ECM apart and sprayed the crap out of it with the cleaner and put it back together. For the past 2 days she reports no problems. I also found one in the yard today, so next time it acts up she can change it and see if it works right, since the ECM is still laying on the floor and not back up behind the dash.

When it is in the floor is a good time to give it the old tap or twist test.
Take it in both hands and twist the case.
Even a good swift kick.
And some times a hair dryer heat on it.
I have tested for more and found more bad ones that way.
Them years are bad about having a shorted or broken circuit board.
If engine running changes with a twist ot tap you have found the problem.
Good Luck