[Lightfoot]

I've posted about some intermittent stalling episodes with my '89 LeSabre before. LN3 3800
About a year ago, I thought I finally had it sorted out after weeks of diagnosing and replacing the ECM, CAM sensor and Crankshaft Position sensor.
(The ECM may have been unnesassary in the end. I replaced that first, just hoping for a quick cure, but the stalling kept happening and seemed to be getting more frequent.)

All was well up until this August, when the engine died three seperate times while running errands on a trip to town. The third time, I was in a handy spot to wait for a tow and it acted like it may not re-start again so I called AAA and had it hauled home.
A couple days later, I thought I'd try it to see if I could back it up on ramps instead of jacking to change the fuel filter. Surprisingly, it started right up. I then let it idle for 10-15 minutes to see if it would stall again. It kept running, even during the lengthy trial and error of setting up the car ramps to get them evenly positioned.
After I installed the fuel filter, I dumped in a bottle of concentrated injector cleaner, since I hadn't used any additives for that in more than a couple years.
For several weeks, I drove the car down our quiet road and back, a 2.8 mile round trip, a couple times per session, every day the weather was clear. Hoping to build my confidence back in the machine while I let the inj cleaner work its way up to the motor. BTW, I also had done a fuel pressure check at the injector rail with a quality gauge, before and after I changed the filter. It was within spec, per the GM service manual.
After twenty or so sorties over several days, without a single stalling episode, I was ready to risk driving the car down the main road again. The last time I test drove it, it seemed to be idling better than it had in recent memory. I parked it in the door yard and got out to open the hood before I shut it off, just to listen to it run a little bit.
Just as I was opening the hood, without warning it just stopped running. It would not restart (and hasn't as of this writing).
Well, now I figured I have to get out the service manual and go through the steps from CHART A-3 again.
I have good fuel pressure. I have spark indicated at all six coil secondary posts and the downstream end of cables 1, 3 and 5. I have tested all six injector harness terminals (unplugged from the injectors) for signal from the ECM (confirmed). I've had the front side spark plugs out a few times to check for fouling and they have the normal coloring... electrodes show no wear. It was hard to tell if they had some dampness from gas but they certainly weren't soaked.
There are NO codes stored in the diagnostic plug (comp). There weren't even any on that day I had it towed. So I haven't done any of the specific tests for the critical sensors that control the ign/fuel.

The only thing I could think of that would prevent the engine from at least trying to start with the above conditions met would be a broken timing chain, which I was almost expecting until I had my brother look inside the valve cover while I cranked the starter over and he saw the rocker arm moving up and down.
I have a suspicion that if I replaced either the (1) Ignition module, (2) ECM, (3) spark plugs (least likely), the engine would start. I just don't believe all six plugs would simultaniously fail completely. Or the cables, Or the injectors.
The fuel pump was replaced in 2012, so it's a possibility it could be at the end of its 'life' but again, I have been getting sufficiant PSI readings at the test port.

I'm open for suggestions

[PunchT37]

The ign modules are prone to fail on those 3800’s. But, I might check my harness and connector 1’st. Check all grounds you can find.

[Formulabruce]

Originally Posted by PunchT37

The ign modules are prone to fail on those 3800’s. But, I might check my harness and connector 1’st. Check all grounds you can find.

My thoughts as well, Ignition module ground can do this with No code.

[BB70]

One thing that will bite you and cause wasted money and frustration is assuming. You are assuming you have fuel press because it tested good previously. Did you check it when it would not start ?

You have inj pulse and spark and no codes, in my eyes the ecm and module are ok- you are missing fuel and or compression. Just because the valves move doesn't mean its in time, it could have jumped a bit. Check the compression with a gauge.

If all checks good, take a fuel sample from the the fuel line at the rail, put it in a gatorade bottle or something and let it sit and settle out- may have water in the tank.

[padgett]

" '89 LeSabre before. LN3 3800". Same engine in the 88-90 Reatta. Is a large section in the Factory Service Manual on "Cranks but does not run".

I usually pour about a 1/2 oz of gasoline through the octopus into the intake and see if different. If runs briefly it is a fuel problem. If nada it is ignition. Triage is good.

BTW the same engine was used in the '90 Bonneville (ob Pontiac). The Magnavox ignition is best replaced with a 91 or later Delco.

[Lightfoot]

Padgett, good information on the ignition. I forgot to mention that I replaced the module in 2016. Also, I would like to try the manual gas insertion test but I don't know were I could access the intake. I thought of shooting some starting fluid into the throttle body but I don't want to contaminate the MAF sensor.
I had the PCV out briefly to verify that it was not sticking. Too much of a P-I-T-A to R&R for a gasoline test port. It's buried behind the alternator and engine harness.

I checked the airbox today for any massive mouse nest plugging. Found none.
Then I tried swapping the original(?) ECM back in, which I hung on to last year instead of recouping my core charge. It made no difference so I swapped it back out to the present one.

BB70, it would be silly of me to make that lengthy post if I had not done all those basic checks when the no-start issue presented itself this current time. I checked fuel PSI immediately after the engine quit and several more times in between failed starting attempts. Every time I push the schrader valve on the fuel rail after turning the key ON, it produces a fountain at least 8 inches high. Plus the gauge read 43 lbs and held each time it was installed.
The engine was running like a watch when it quit so it's extremely doubtful that there is now a compression problem. It is nearly the last thing I have NOT tested, so I may do the front three cylinders just to eliminate it. But I'll need to pull the battery to charge it first. Another P-I-T-A.

In the mean time, I'll double check the ground to the IGN module, but this is highly redundant, since I had the SPARK tester plugged into the cables and it was flashing while cranking the starter. Also, I believe it is grounded via the aluminum bracket it is bolted to but I'll pull the harness connector and check treminal M for continuity to ground.

This car is my only form of transportation so I appreciate everyone who is helping me brainstorm this dilema.

[PunchT37]

Check ALL grounds. Also, really check harness for any rubbing. Sometimes you have to pull open the conduit on the larger sections to see 1 wire with exposed copper causing INTERMITTENT problems. Check for oil soaked wires leading to the sensors.

I’m starting to bet that this is a harness/grounding problem.

[mgarblik]

You have provided allot of good information and it looks like you have followed some tests and verified running conditions and used a scan too. I am just going to add a few items you can check to your list and other peoples suggestions. This is now an old car and grounds are of course critical. I think there are a bunch of them that go to a bellhousing stud. Check them. Also possibly to the thermostat housing. (terrible location) Check them. Also the big aluminum mounting plate for the ignition coil pack/module to the block. Check all of them. Clean and tight. 3800's have a slightly goofy plastic channel/harness guide that attaches around the timing cover where the crankshaft position sensor is attached. They are well known for chafing the little crank sensor wires and shorting to each other or grounding to the timing cover. You need to carefully inspect that wire and the harness all the way from the sensor past the connector where it continues behind the coil pack mount. Follow it as far as you can and look for smashed/ oily/damaged wires from that sensor. That crank sensor harness is CRITICAL to the engine starting and running. Believe it or not, it will start and run without a cam sensor functional. It will just crank longer and run in batch fire mode. Most people won't notice the difference. So the cam sensor won't keep it from running. I have a feeling your issue is in the crank sensor/wiring harness to that sensor. Great engines, hope you get it sorted out.

[Lightfoot]

mgarblik; Thanks for the reply.
Yeah, I went through a lot of that opening up conduits and checking wires last fall when the original stalling problem got increasingly frequent and damn near left me stranded a couple times. I never found any chafed wires but there were areas were the factory wrap had loosened up from oil residue. Before I replaced the crank sensor, I discovered there was engine grime in and around the slots where the vanes pass through. I cleaned that up with brake clean and left it alone at first. At that time I think the CAM sensor was actually defective. I had a code 41 at that time also. I decided to replace the Crank sensor for peace of mind, after I had replaced the CAM sensor.

That part of the wire harness from the crank sensor that goes up behind the timing cover is a b__ch. I never did get that fully EXPOSED so I could inspect each wire. The plug that goes on the sensor simply won't fit through that passage way between the timing cover and the block. I think I ended up just trusting the continuity checks between that plug end and the IGN module. I think I'll double check the continuity on those tommorrow.
I also did a lot of continuity checks (last year) for the wires running from the componants to the ECM.

Today I tried to determine the source of the ground to the IGN module. The schematic in the manual doesn't show that the module body is grounded to the mounting bracket. All it shows is the wire coming in from the common ground wire on the CAM and CRANK sensors, which grounds internaly in the module. I had a power reading when I metered that connector to BAT + with the key ON.

I also tried to induce ether, and then gasoline into the vacuum port on top of the throttle body adaptor. I never had so much as a sputter on any cranking attempt. Not sure if I used enough gas to be sufficient. I Think it may have been a little over an ounce in two syringe fulls.
The ether was frustrating because the seal around the spray button leaks badly and dribbles most of the fluid down the side of the can instead of shooting through the nozzle. I'd say only 20%-25% of the fluid was going into the nipple. I need to purchase a new can that will blast it into the plenum.

QUESTION: I am considering spraying the ether in through the main throttle body opening. There is a fragile looking honeycomb grid clipped in there. I would like to know if that could be damaged from ether contamination. It looks like the same stuff that is inside catalytic converters.
It has a snap ring holding it in. I don't know if I might end up crumbling it if I attempt to remove it, or when I'm putting it back in.

One last thing for now; I did perform a compression test on cylinders 1, 3, 5 today. the pressures were fine. 145. 137, 133.

Oh yeah, posting pics of the plugs.

[sdbob]

I had a 89 buick Park Avenue many years maybe 15 yrs ago. I new napa ecm was already installed. Had problems starting and running. Local buick dealer mechanic told me only use GM rebuilt ecm they are better quality. Then another problem missing bad. He said something else effected by ecm went bad. Fixed that(sorry I'm not remembering the module)Got that figured out. Then trannny started missing shifts. Mechanic said yep that's another major problem with some seal even when brand new. This is what happened to me.

[Formulabruce]

Find the PCV and unhook it. It should go to an intake port on one end. Try your starting fluid in there.

[mgarblik]

That honeycomb grid is aluminum and won't be damaged by ether, but I would not use it for testing. The grid is an Air Straightener, according to GM. It's right in front of the mass air flow sensor. That sensor has tiny tungsten wires in it that get hot to measure air flow in the system. For a safer starting fluid, I like to use WD-40 spray can only. It is combustible, but much safer than Ether. Just for fun, disconnect the MAF sensor harness and try to start the engine. If it starts, you found your problem. A failed MAF sensor rarely sets a code, but it will cause a no start. When you unplug it, the PCM reverts to speed density fuel injection and substitutes MAF readings with the MAP sensor. Worth a try.

[Sirrotica]

My own 87 Bonneville that I drove until it was rusted apart.

Bad plug wire caused the ignition module to blow. Seems even if they're marginally bad, and send the full 60,000 volts through the module for a split second, it's toast. Mine wasn't even bad enough to produce a constant misfire, just a very light intermittent miss.

Had a no start that was a bad crank sensor. Fairly common failure part when I worked in a buick dealership.

One other time the smart chip fell out of the ignition key. My daughter was sitting in the car as I was trying to start it and she noticed it was missing the chip. I retrieved a spare ignition key, and it started right up.

[mgarblik]

That's an excellent point about the security system and that could be the cause of all your misery. You need to verify what VATS system your particular car has. There were different generations of the VATS system. I would bypass that entire system as part of your diagnosis. It can be done with common electrical resistors. You use an ohmmeter to determine the resistance of the chip in the key, then wire the resistor value into the VATS wire under the steering column. There are many Youtube videos that explain in greater detail how to do it. Pretty simple. Based on what you have posted you won't have any trouble bypassing the system. Great post Sirrotica.

[Lightfoot]

mgarblik; Can't wait to try that trick with the MAF sensor tommorrow. I've got a couple of spares that I gleaned out of a pick-a-part yard ten years ago. One I even carried with me on long road trips. I had a MAF go bad on me in a '90 LeSabre that was my daily driver 15 years ago. It started running terrible and almost died at a traffic light until I got her home. I'm pretty sure it threw a code because I remember the SES coming on. I think I replaced that one with a salvage yard piece also.
One of the few bad engineering ideas on these 3800s is how they attached the MAF to the throttle body with those soft phillips head screws. Super easy to strip the heads out if you are not extra careful. And they do get siezed into the aluminum screwholes. Mine currently has one screw missing because the threads on the screw galled up last time I removed the sensor to clean it a couple years ago.

I have been watching a bunch of Vice Grip Garage videos lately and I recalled seeing him using WD-40 for starter fluid. I had some spray bomb silicon sitting around which I think might also work but I wonder what the silicon might do to the O2 sensor.
I had my sister pick up a new can of ether today at Wally World but I haven't tried to use it yet. It was getting dusky when she got home.

What I got done today was re-checking all the critical wires that go between the CAM sensor, CRANK sensor, and IGN module. I drew my own diagram that forms a triangle between the three componants so I can see it more clearly. There are seven 'circuits' that you can check with an ohmeter and it is quite effective for determining if there are any 'mystery' defects in the harness.
I also unbolted the coil packs to check the primary connectors for resistance, etc.
I did not find any bad wires or grounds anywhere so I'm ready to try the ether shot (or WD-40) again, but I'll definately check that MAF first.

[Lightfoot]

Mgarblik, it took me so long to compose my last post that I think you posted while I was writing and I failed to notice it when I finally hit the submit button.
I don't know if you were addressing me or Brad, but just in case, I'll let you know my '89 Buick doesn't have the security chip in the key. They didn't start using those in the H bodies until at least 1992.

Well, I tried the MAF idea that you suggested and nothing different happened. I was actually phsyched up about my MAF being toast because I wanted to believe I finally got to the bottom of the malady.
So I made an attempt at shooting WD-40 in the throttle inlet. First try was botched because I forgot to hold the throttle wide open so it could get past the butterfly. I corrected that mistake and gave it another good squirt. Hard to tell how far in there it was going because of the Air Grid. I sprayed until the fluid was running back out the bottom of the inlet. Still no sputter at all when cranking.
My battery is waining so the crank speed was slowing down by this time. I hope that doesn't effect the intensity of the spark at the plug.
I quit for the night and removed the battery to take it in the house for charging.
So I still can't guarantee it's not a no-spark issue. My initial tests indicated that I had both spark and fuel, plus a pulse signal from the the ECM at the injector plugs. One of those two test was a false flag (not the fuel pressure check).
I am on the verge of pulling the injectors to see if they are plugged or have them bench tested somehow.
Anyone know if the injectors can be 'flushed' clean if they are plugged with sediment from the tank?

[Sirrotica]

They didn't start using those in the H bodies until at least 1992.

Now that you mention it, it was my 92 SSE Bonneville that the chip fell out of the key.

Sorry for the confusion, but it was around 25 years ago, I just forgot which car it fell out of, but it was the 92 I owned, that replaced the 87 Bonneville.

[mgarblik]

OK, in this case, no security system is a good thing. It is very unlikely you have a mechanical injector problem where ALL of them have failed at once. I have never seen that happen. One or two can be partially clogged and it will not run well, but not cause a no-start. I think you are back to ignition. Here is a simple test. NOT recommended by GM, but a quick and easy test for secondary ignition intensity and function. Pull two plug wires off the same coil pack and crank the engine. You should have enough secondary intensity to jump that 1 1/2" gap between the two terminals. If you do not, you have an ignition problem. GM does not recommend this because the jumping spark COULD take an ignition module out. We used to do this test when I did roadside service because we needed a quick easy test of ignition. Never killed an ignition module in dozens of tests. But test this at your own risk. Just crank 2-3 seconds. You should have a sharp BLUE spark.

[Lightfoot]

I finally got the battery back in it so I could try a shot of ether. It helps to let my mind rest a few days so I can think logically about the steps I need to take and in what order.
I noticed a location to inject the ether so it shouldn't 'wash over' the MAF electrodes. There is a tube going from the front valve cover to the throttle body, which I presume is part of the PCV system. I've always known it was there but it didn't jump out at me when I was looking for a place to spray into the manifold.
The nipple for this hose is right in front of the throttle plate so I have to remember to hold the cable open when I spray. I only did one three second burst and quickly covered the nipple with the hose to try cranking. No firing ocurred still.
I have one more idea that I thought might work. If I pinch down the fuel return line to override the regulator to get max PSI out of the pump, perhaps that could overpower any crud that is plugging the injectors, if that is what is going on.
I think I might have to leave the clamp on the line while I'm cranking or the pressure will just drop back down to normal after the first primer shot. My theory is the worst that could happen is the engine would just run rich or flood out, if it did start. I wouldn't let it run for more than 4-5 seconds anyway.
I just need someone to tell me if there is a possibility of doing internal damage to the injectors from too much pressure. Service manual says the pump should devlope over 75 psi with the return line clamped.

But before that, I think I'm going to dig out my old module from pre-2016 and put it back in for a test mule. I had it in there for about a week last year when I was trying to sort out the problems I was having then. It did still run the engine but after I installed a new CAM sensor, the SES light kept coming on for Code 41, immediately after clearing out the diagnostics. I tried clearing them three times and it would just come right back. So, I swapped back in the newer module and bingo, the light stayed out. At that point I decided the (original) module was never going back in, but I hung on to it. If they weren't so expensive, I probably would have thrown it out.

Now if I decide to try that coil ARC test, I can do it with the old module and if it fries it, Oh well.
It may even start up and run again with that old one on. If it does, I'll be ordering a new one from RockAuto.

Cold rainy weather kept me from spending too much time with it today.
Thanks for the replys.

[Sirrotica]

I had a customer with buick 3.0 V6 Grand Am that silted up the injector on one cylinder, resulting in a dead cylinder. There is a very fine screen sock at the entrance to the injector that I was able to remove, clean, and reinstall that solved the missing cylinder. The screen is sock shaped and no amount of fuel pressure is going to do anything to clean it out. The dirt has to come out from the same direction it went in at. Disassembly is the only way to unclog it.

If the dirt went through, it would ruin the injector as they are a very fine finish and fit. The sock is the last defense to stop the dirt before it lodges in the injector pintle valve sticking it either open, or closed, and possibly scoring the moving parts.

Chances of blocking fuel flow to all 6 injectors at the same time is not likely at all, you're chasing a non problem IMO.

I'd be looking at the crank sensor as much more likely to have failed, they do sometimes act up before dying, as your symptoms suggest.

Quote about crank sensor symptoms as they deteriorate:

Usually a problematic crankshaft position sensor will produce a few symptoms that alert the driver of a potential problem that should be serviced.

1. Issues starting the vehicle
The most common symptom associated with a bad or failing crankshaft position sensor is difficulty starting the vehicle. The crankshaft position sensor monitors the position and speed of the crankshaft and other parameters that play an important role when starting the engine. If the crankshaft position sensor is having a problem, the vehicle may have intermittent starting issues or may not start at all.

2. Intermittent stalling
Another symptom commonly associated with a problematic crankshaft position sensor is intermittent stalling. If the crankshaft position sensor or its wiring have any issues, it can cause the crankshaft signal to be cut off while the engine is running, which can cause the engine to stall. This is usually a symptom of a wiring problem, however a bad crankshaft position sensor can also produce this symptom.

3. Check Engine Light comes on
Another issue of a potential problem with the crankshaft position sensor is an illuminated Check Engine Light. If the computer detects a problem with the crankshaft position sensor’s signal, it will activate the Check Engine Light to alert the driver of the problem. A Check Engine Light can also be set off by a wide variety of other issues so having computer scanned for trouble codes is highly recommended.