Engine Died then came back to life

[76C10Stepside]

Howdy folks. I've been having one thing after another with my 1989 S10 Tahoe with 4.3/auto. It is in very good condition for a 30 y/o truck, with very low miles (53k), engine very strong.

Couple days ago, the engine shut off while idling at stop lights three times, but started right back up. It has NEVER done this before. It was idling at 750 rpm all 3 times, was running exactly at normal temp, and did not make any weird sounds, etc. When I got to destination a few miles away and was about to shut it off, it died again and would not restart. No smell of gas. Happened to die at a mechanic's house but was going there for a different reason (ironic). He said his Tahoe did the same thing when the fuel pump went out. Engine would not fire with starting fluid (only tried twice). Had it towed home yesterday.

Today, checked for trouble codes, just got the code 12, no error codes. Sprayed starting fluid and it fired right up! Was NOT expecting that.
Idle started at 1250, then 1000, then 750 after about 2 minutes (not at normal temp yet). Ran it for several minutes, ran very smoothly. The only noise was from alternator, but not loud (thinking bearing is on the way out). Checked ammeter and it was dead-center.

I love this truck, but live out in the country, and really need dependable transportation. If I can't get all the bugs worked out of it, will have to move on. Any and all help diagnosing this greatly appreciated!

Here's a history of work (starting with most recent) I've done on it since I got it several years ago. Note that it has sat for about half of that time due to a shorted dimmer switch that took awhile to pinpoint:

1. Just installed new clutch and bearing on the A/C compressor. Bearing was getting noisy and engine was idling up and down. Idle was "better" after this, but still "funny" on some days, fine on others, has had me worried.

2. New MAP sensor (attempt to fix the unstable idle, and occasional misfire). Did not really help.

3. New fuel injector (had already replaced the other one).

4. New valve seals, timing belt, oil and filter change. Later found oil cooler hose clamps were loose, which was causing a slow drip. No more drip.

5. Rebuilt throttle body (including new pressure regulator) and replaced one injector after it started spraying with engine off. It dumped a LOT of gas into the crankcase, had to drain oil and change filter (OK after that, but seems to have cooked the valve seals). Also replaced the fuel filter. The throttle position sensor failed, probably due to my spraying carb cleaner on it while still mounted to throttle body (duh), so got a new one.

6. Replaced dimmer switch (was causing no crank and apparently also shorted out the starter, but not confirmed, as a shop replaced the starter with out my permission, instead of diagnosing and calling me as instructed).

7. Replaced starter (see above). Had replaced starter only 1 year prior too, and had no issues with it.

[Mr_Rich]

After thirty years my vote would be the fuel pump. You might have a clog somewhere that might be related.

[76C10Stepside]

Originally Posted by Mr_Rich

After thirty years my vote would be the fuel pump. You might have a clog somewhere that might be related.

Thanks for weighing in. That's 2 votes for fuel pump.

Drove into town this afternoon. Got to first destination, no problems. On the way to the second destination, it stalled again at a stop light. Then again at a stop sign a couple of miles later. This time, the check engine light and dash flashed on/off a couple of times before it stalled. All other times, it is idling right at 750 rpm then just shuts off.

This truck has the digital dash, so the tach is just bars. But the engine sounds like it is idling at a steady rate. I don't think it's slowing to a stall or going up/down at all.

Parked the truck and walked the rest of the way to second destination, then walked back. Truck started right up. Drove it all the way home without further incident, but I did avoid any stops, tried to keep the revs up to 1000 at the 3 stop signs I had to stop at. My road is 50 mph for the last 6 miles (before that it's 40 for several miles). There were no problems at all. Plenty of throttle response, etc.

If the fuel pump were failing or there was a clogged filter sock, I would expect the engine speed to rise and fall, and maybe to die when actually moving down the road. But I'm used to carbureted engines, so...

[Mr_Rich]

You talk about in-town driving it seems. If you got out on the highway and it started bucking and cutting out like I would expect with a fuel pump that's on its last legs maybe that would be more proof. That's what mine did. It was a dirty job. I dropped the tank on mine and replaced both the pump and the sender assembly since my gauge was acting up. That was two or three years ago already...

[76C10Stepside]

Originally Posted by Mr_Rich

You talk about in-town driving it seems. If you got out on the highway and it started bucking and cutting out like I would expect with a fuel pump that's on its last legs maybe that would be more proof. That's what mine did. It was a dirty job. I dropped the tank on mine and replaced both the pump and the sender assembly since my gauge was acting up. That was two or three years ago already...

That's correct. Though there is a lot of 40 to 50 mph driving on country roads. I figure 50 mph should be fast enough to tell if the fuel pump is struggling to reach the required pressure and flow rate. And it idles steady until it cuts out. Just does not seem like fuel pump. This year did not include a test port on the fuel line, so I have not been able to measure the fuel pressure and flow rate.

Before I take on an in-tank fuel pump/sender replacement, I'd like to check anything else that is a possibility and is easy enough to check.

This was my father's truck, and I have all the records he kept for it (I think). Found an invoice from 2003 that says it "died and won't restart" and "test fuel pressure & flow. scan computer system data on scanner. has out-of-range temperature sensor. test circuit & component. need to replace this part first, then retest system. coolant temperature sensor - replace". I'm guessing they just check for trouble codes, found the temp sensor out of spec, and replaced it, and never got around to testing the fuel pressure and flow. There is no mention of the results. Hmm... The temp sensor for the dash guage is working correctly, but maybe the one that communicates with the ECM is going out?

Going back farther, found an invoice from 1998, "cranks, won't start. found no spark & no signal to fuel injectors. has fuel pressure. scanned computer system. performed individual circuit tests." and "removed & disassembled ignition distributor. replaced module & pickup coil. reinstalled, and adjusted timing.".

Found nothing to indicate that the fuel pump has ever been replaced. Hard to believe, though...

Will check the distributor and test the coil. Will also do simple resistance test on the ignition wires, but not sure a simple resistance test will reveal anything but a broken wire. From what I've read recently, this is not an effective way to measure the condition of modern carbon based ignition wires. Should probably just replace them.

[sntrym95]

While you're testing the distributor, test the coolant temp sensor in the intake manifold as well. Sounds like that might be the culprit again if it's giving false readings to the ECM.

[Mr_Rich]

That 4.3L engine is every bit as good as a V8 as far dependability. It hasn't been mentioned, but you should have a fuel filter in there that could be replaced. I looked back and it was actually five years ago I replaced my fuel pump (how time flies!) and I really noticed it stumbling on the freeway at 60-70 mph and not so much on surface streets.

[76C10Stepside]

Originally Posted by sntrym95

While you're testing the distributor, test the coolant temp sensor in the intake manifold as well. Sounds like that might be the culprit again if it's giving false readings to the ECM.

Will do! This has been a cause of no-start on this truck before I owned it.

[76C10Stepside]

Originally Posted by Mr_Rich

That 4.3L engine is every bit as good as a V8 as far dependability. It hasn't been mentioned, but you should have a fuel filter in there that could be replaced. I looked back and it was actually five years ago I replaced my fuel pump (how time flies!) and I really noticed it stumbling on the freeway at 60-70 mph and not so much on surface streets.

Yeah, it pulls real good, like a V-8, and runs smooth most of the time. Have only put a few thousand miles on it in the several years I've had it.

I replaced the fuel filter when I rebuilt the throttle body and replaced one injector (have since replaced the other injector), and have not driven it much since b/c it had a short that took a year to get around to finding/fixing. So, I was thinking the fuel filter was still good. But don't know any way to test the fuel pressure and flow rate on this year (no test port on fuel rail). Anyone know how to do it?

When you had the stumbling, was it AFTER installing the new fuel pump, but before replacing the fuel filter?

BTW, found a table in the manual that lists what resistance should be for a given length. Heading out to start on it, will report back later.

[Mr_Rich]

Originally Posted by 76C10Stepside

Yeah, it pulls real good, like a V-8, and runs smooth most of the time. Have only put a few thousand miles on it in the several years I've had it.

I replaced the fuel filter when I rebuilt the throttle body and replaced one injector (have since replaced the other injector), and have not driven it much since b/c it had a short that took a year to get around to finding/fixing. So, I was thinking the fuel filter was still good. But don't know any way to test the fuel pressure and flow rate on this year (no test port on fuel rail). Anyone know how to do it?

When you had the stumbling, was it AFTER installing the new fuel pump, but before replacing the fuel filter?

BTW, found a table in the manual that lists what resistance should be for a given length. Heading out to start on it, will report back later.

Fuel filter didn't enter into it. The fuel pump was failing along with the gauge so the whole in-tank unit was replaced. It turned in to a project. No stumbling since it's been replaced five years ago.

I'm thinking to cut open the fuel filter to check for any garbage. Could be garbage in the gas tank from moisture because the vehicle has sat for long periods of time. I've seen diesels collect stuff that looks like gray dishwater. Gas vehicles can have rusty gas tanks. That causes trouble.

I think I've measured spark plug wires in 1.5K to 3K R's. You don't want to see the infinity symbol on the meter.

[76C10Stepside]

Checked resistance on the coil to distributor and the #2 plug wire using my $5 cen-tech multimeter set to the 200k range. RESULTS:

Coil Wire (8.5 inches long): 02.4 (2,400 ohms). Chiltons lists Min/Max for 0-15 inch HEI wires as 3000 to 10,000 ohms, so looks like it's degraded. The connector on one end had some corrosion, cleaned it up and put some dielectric grease and retested, got same reading.

#2 Cylinder (around 24 inches): 05.7 (5,700 ohms). Per Chiltons, Min/Max for 15-25 inch length should be 6000 to 20,000 ohms.

These are good quality Packard 8mm Silicone. Hate to replace them if OK, maybe end up with worse wires.

Removed distributor cap. The aluminum electrodes had a LOT of scale (white powder) on them (never seen this much before), but it was easily scraped off and cleaned up nice. The aluminum base plate was also corroded (and some light powder on other parts), but cleaned up easily. Used a toothbrush and squeeze bulb to remove all debris from cap and distributor parts.
Also wiped the rotor contact off with a paper towel, which looked good.

My Chilton's says 4.3 engine uses an EST distributor, but does not show any pictures of 4.3 distributors, and the pics google showed me for 1989 s10 4.3 distributor do NOT look like mine.

Put it back together and started engine, which ran fine. About 30 seconds into it, the alternator started making a lot of noise for about 30 seconds, then quieted down, but a bit later made some noise but a LOT quieter than before. Assume it's a bearing. The alternator is outputting normal range, no jumping around (was 1 bar above the neutral point at 1250 rpm).
Chilton's says it's a CS-130 alternator and that they cannot be repaired. Ordered a new Remy 105 amp alternator from a local chain, only $72.99 with lifetime warranty (O'Reilly wanted $99.99 for a reman unit).

Will look for HEI ignition wire sets later...

[Mr_Rich]

It looks to me that you know what you're doing. I just think those parts need a lot of reconditioning. I'd use a small brass wire brush to clean up the corrosion in the dist. and a spray bottle of air to blow all the particles away. I think your spark plug wires are in range. I used to like using Accel dist. caps with the brass contacts until they started making them in China and I had problems with fit. Stopped using them at that point. I use some spiral wire wrap to protect some of those smaller wires that are exposed. Maybe the ignition module needs a fresh coat of insulating grease too.

[Mr_Rich]

The CS-130 alts. can be repaired; it's just more difficult than the typical alts. that came before it. The bearings can be replaced and if you have a brush kit, those too. The windings are brazed to the diode trio. That's the difficult part.

[76C10Stepside]

Originally Posted by Mr_Rich

It looks to me that you know what you're doing. I just think those parts need a lot of reconditioning. I'd use a small brass wire brush to clean up the corrosion in the dist. and a spray bottle of air to blow all the particles away. I think your spark plug wires are in range. I used to like using Accel dist. caps with the brass contacts until they started making them in China and I had problems with fit. Stopped using them at that point. I use some spiral wire wrap to protect some of those smaller wires that are exposed. Maybe the ignition module needs a fresh coat of insulating grease too.

Thanks for the encouraging words! After working on it today, I had some place to go. It started right up and I drove it several miles with no problems at all. Three hours later when it was time to go home, it WOULD NOT START. Plenty of cranking power, just no fire at all. Sprayed starting fluid in the throttle bores, and NOTHING. It should fire even with a dead fuel pump.
Also, with the ignition on (between cranking), the battery icon was flashing on and off. Does this indicate anything? It has the infamous digital dash (which was replaced with a new one at some point).

I'm inclined to agree with you that the ignition wires are at least good enough not to cause this particular problem, where it runs great most of the time. If it was missing or had a lack of power, I would suspect them, but that is not the case.

Could this later type of alternator cause a no-fire condition? Hard to see how that could be. It has been working fine, always get a good reading on the guage EXCEPT when the engine won't start, LOL! What else could cause this? Am getting NO trouble codes. Need to get a list of parts that don't register on the computer when they are bad with an ODB 1 system.

I'm not familiar with this type of ignition module. I had an older one go bad because the connections inside were exposed to the weather and corroded really bad (it would suddenly die at any speed). This one has only died when idling a total of 5 times, and has refused to fire at all 2 times.

Tomorrow is going to be fun, 6 mile walk to the truck and see if it will start right up again OR...

[Mr_Rich]

No fire; I vote on the ignition module. You have to have the insulating grease on the bottom of the module. That's one of the important points that is always made and I follow that direction.

[ChevyTech]

Originally Posted by Mr_Rich

No fire; I vote on the ignition module. ...

I agree.

From the beginning of this thread it sounds like ignition module to me.

Many parts store will test it for free if you bring it in. These have a high failure rate and I would not buy the cheapest ones.
As stated make sure you put heat sink paste under the module or it will fail.

[76C10Stepside]

Originally Posted by Mr_Rich

No fire; I vote on the ignition module. You have to have the insulating grease on the bottom of the module. That's one of the important points that is always made and I follow that direction.

Thanks Mr_Rich and ChevyTech! I was hoping it was the ignition module, but had not got around to checking it, because I only have a Chiltons manual for this truck, and it does not show any pictures of the distributor or the ignition module for the 4.3! Very inconvenient.

According to the Chiltons, the 4.3 uses an EST distributor, and the ignition module is located inside the distributor. There is a drawing of the EST distributor for the 2.5 that identifies the "module" as a part that is screwed down to the distributor base plate.

The distributor cap bolts are 7/32". Do you know what size the two bolts that attach the ignition module to the distributor are? What is the purpose of the "silicone lubricant"? I need to leave soon, hoping you see this. Thanks!

[76C10Stepside]

OK, I know what the silicone lubricant is for now. Heat sink paste/compound/grease. One guy says to clean all surfaces on the ICM, heat sink and base using thermal surface purifier OR acetone OR alcohol before applying the grease.

The 2.5 EST distributor uses a Hall Effect switch, so is a lot different. Mine uses a traditional rotor and electrodes on the distributor cap.

Did not find instructions online for replacing the ignition control module on my particular distributor. Looks like I need to remove the rotor (must be a fastener on it somewhere). There is no dust cap. Don't know what the "donut" in the middle is called or how to remove it (looks like a coil of some sort), and it's really in the way. Maybe it will slide off once I get the rotor off...

[Mr_Rich]

I took pics of a spare dist. I have on the shelf; no ignition module on this one. I think you can use the same screws that hold the dist. cap on.

This one I have has its share of rust and corrosion. I would wire brush and polish the aluminum and copper with some type of aluminum polish. I think that would hold off future corrosion from quickly setting in. I live ten miles from the coast so I have a similar problem. Clean the base as much as possible before you coat the ignition module with the insulating grease. You can see the rotor is just a push-in and has an indexing slot. Nothin' to it...

Oh yeah, and the copper coil doesn't come off. Just work around it...

[76C10Stepside]

Thanks for the photos and info! Your spare looks exactly like mine, just rustier.

Had a fun day today, lol. Rode my bike 6 miles to the truck with a backpack with a few choice tools in it. The truck still would not start, so set to work.

Discovered the socket set was missing from the tool bag in my truck, so could not remove the ignition coil to have it tested, and did not bring my multimeter, so could not test it in place either.
Removed the ignition module. The two terminals that connect it to the "donut" were very rusty. The external terminals were all like new because they have weatherproof plugs. Not so for the inside plug. The rotor would NOT pull off. Must be rusted onto the shaft. I should probably replace it real soon...

Rode another 6 miles to the auto parts store. The ignition module tested "good", but bought new ignition module anyway, and a new coil and dielectric grease. They did not have any heat sink compound and do not rent socket sets, so rode another mile to Harbor Freight Tools and got a really lousy $5 socket set. They didn't have heat sink compound either.

Rode 7 miles back to the truck (stopped on the way for a burger). Removed the old coil, only to find that the new coil does not have the mounting brackets needed to mount it to the intake manifold. The "instructions" say to re-use the old mounting brackets. GREAT. They are riveted on with heavy rivets, not intended to be reused. Did not have anything that could be used to temporarily mount the new coil, so installed the old one.

The new ignition module did not come with new bolts, but the old ones are ok. Installed the new ignition module, which came with just enough silicone heat sink grease. Used dielectric grease on the inner terminals and the mounting bolts so they won't keep rusting away. The distributor base is as clean as I could get it with materials on hand.

The truck started up and ran with just the new ignition module, and drove great all the way home. Glad I did not have to ride another 6 miles in the dark, hills and all!

Will test the old coil tomorrow. Even if it tests good, I think it should get replaced (both the ICM and coil look like the original units). I paid a little more for a borg warner coil. Am not happy that the more expensive Borg Warner coil I bought was not a bolt-in replacement and looks cheaper than the old one. Think I'll take a look at what the other auto parts store I called has and see if it is better.

Still planning to replace the alternator. The new one I ordered is only $73, but I would not mind replacing the bearings and brushes on the old one if I can save at least $50. Mr_Rich, you mentioned that the CS-130 alternators can be repaired, bearings and brushes can be replaced (and that the windings are brazed to the diode trio, the difficult part). Can you point me to more information on how to work on this model and where bearings and brushes can be obtained? Thanks!

[Mr_Rich]

I think coils are much more robust than those ignition modules. That was your big worry taken care of right there. Glad you made it home. Those CS-130 alts. are kind of a pain. I replaced mine with a CS-144 but those aren't necessarily a drop-in. I used the serpentine brackets from a '90 Cadillac on my truck that you see in my avatar. I had to use car pulleys because they are about 3/4" difference of offset. The problem with a lot of these parts are that they are obsolete. A lot of the parts in my collection are 15-20 yrs. old. I did a 140 amp kit conversion on the CS-130 alt. that I had in my truck before I swapped out to the CS-144. Summit Racing sold a kit for the CS-130 upgrade. They may still have it; I haven't looked for it. Generally I've found auto parts stores carry the sealed bearings. They can be replaced with gear pullers and tapped out of the cases. Not too bad of a job, IIRC. The brushes can be a pain and I don't know if those are available.

[76C10Stepside]

Originally Posted by Mr_Rich

I think coils are much more robust than those ignition modules. That was your big worry taken care of right there. Glad you made it home. Those CS-130 alts. are kind of a pain. I replaced mine with a CS-144 but those aren't necessarily a drop-in. I used the serpentine brackets from a '90 Cadillac on my truck that you see in my avatar. I had to use car pulleys because they are about 3/4" difference of offset. The problem with a lot of these parts are that they are obsolete. A lot of the parts in my collection are 15-20 yrs. old. I did a 140 amp kit conversion on the CS-130 alt. that I had in my truck before I swapped out to the CS-144. Summit Racing sold a kit for the CS-130 upgrade. They may still have it; I haven't looked for it. Generally I've found auto parts stores carry the sealed bearings. They can be replaced with gear pullers and tapped out of the cases. Not too bad of a job, IIRC. The brushes can be a pain and I don't know if those are available.

Thanks for the info. Did not have any luck searching Summit for CS-130. Their search is divided into year/make/model OR make/engine (and 4.3 not specifically listed). Selected year/make/model and "Alternator and Generator Replacement Parts" category. Some bearings and brushes were listed, but no info on which alternator they are for. I'll just buy the new one and hope it lasts as long as the old one. The old one does not look old, but I did not find any receipts for a new one, which is kinda funny, as this truck lived a few miles from the ocean and was parked outside for most of its life. But it was a dry climate, which helped. The only real accessory on this truck is A/C (has manual windows and locks), so it would probably do just fine with an 85 amp unit, but opted for the 105 amp. It will be well worth the $75-80 to avoid another possible breakdown away from home that would probably destroy the new serpentine belt I just put on it, not cheap at $40!

[76C10Stepside]

Thanks for the pics of the fuel pump/sender. I missed seeing that post earlier.

The truck has been running great since I replaced the ignition module. I ordered a new alternator, but am wondering if I should replace it. Just gave it the "spin test" to see if the bearings are worn, and it spun 1 to 1-1/2 turns with no slop, no noises. It's operating correctly. The only sign of problems is that it makes intermittent noise that I had assumed was bearings, but now I don't think so. I've watched the "ammeter" on the dash both while it's making the noise and not, and it it always steady at the mid-point, or one bar above it. Is this intermittent noise "normal" for this alternator? Would you wait until it fails (IF it fails), or replace it NOW?

[Mr_Rich]

Originally Posted by 76C10Stepside

Thanks for the pics of the fuel pump/sender. I missed seeing that post earlier.

The truck has been running great since I replaced the ignition module. I ordered a new alternator, but am wondering if I should replace it. Just gave it the "spin test" to see if the bearings are worn, and it spun 1 to 1-1/2 turns with no slop, no noises. It's operating correctly. The only sign of problems is that it makes intermittent noise that I had assumed was bearings, but now I don't think so. I've watched the "ammeter" on the dash both while it's making the noise and not, and it it always steady at the mid-point, or one bar above it. Is this intermittent noise "normal" for this alternator? Would you wait until it fails (IF it fails), or replace it NOW?

I think it could wait. These alts. also have a function that regulates voltage when they get hot. I have a PDF where I read this. Sometimes the alts. make noise when the battery has drained a bit low and it takes a bit more amps to charge the battery. We have the cold weather now so the charging system is going to be doing extra work. You can do a test and turn the heater on high, headlights on, wipers and radio on, and measure the voltage while the truck is idling and revving. Maybe that will give you peace of mind as long as you have near 13 VDC.

[76C10Stepside]

Originally Posted by Mr_Rich

I think it could wait. These alts. also have a function that regulates voltage when they get hot. I have a PDF where I read this. Sometimes the alts. make noise when the battery has drained a bit low and it takes a bit more amps to charge the battery. We have the cold weather now so the charging system is going to be doing extra work. You can do a test and turn the heater on high, headlights on, wipers and radio on, and measure the voltage while the truck is idling and revving. Maybe that will give you peace of mind as long as you have near 13 VDC.

I'll do that test first thing tomorrow. Thanks!!!