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Discussion Starter #1
The 94 Fleetwood I've been working on decided to simply stop running about a month ago and had to be towed back. Initially we thought the problem was the fuel pump and there were signs the pump was weak and not producing enough pressure. Since we had a new pump on hand, I dropped the tank and replaced the pump and wiring. After the pump was installed, jumping the pump relay gave us 41psi measured at the test port and it held that pressure for quite a while (the test gauge leaked a tiny amount). Unfortunately after that, the battery got connected up backwards and the PCM patently died. Thread on that here; http://www.impalassforum.com/vBulletin/35-pcm-programming-engine-management/1312490-fleetwood-brougham-pcm-interchange-2.html#post12077858

The PCM has been replaced and wiring damage at the PCM has been corrected. Unfortunately, while the PCM replacement got the car back to where it was before the reversed battery made an appearance (car now primes and fires the ignition system again) the car still doesn't run. At this point, the car doesn't start and seems to be acting like the ignition timing is way off. There are pops from the exhaust and occasionally the intake. The exhaust manifolds next to some cylinders do warm up after hearing these pops. The ICM has been checked out repeatedly using parts store testers, the coil's okay based on primary and secondary resistance testing. I have tested the coil and some of the cylinder wires for spark with a timing light (couldn't find the timing marker on the engine at the time) to verify the system was firing. The Optispark cable is new as of last year and was GM NOS of relatively recent production; it ohms out okay and is not damaged in any way.


Here is a video containing audio recordings of what the car does when cranked - first with the microphone on the fender, next with it on the ground under the rocker panel by the driver's door and finally next to the exhaust tip out back of the car. These are three separate attempts at a start as I was working by myself.





This is smelling like an Optispark failure to me - logically, the Opti controls timing/advance, yes? Could someone confirm this or suggest other tests to perform?

Edit: If it makes a difference, the engine is mostly a rebuilt LT1 from a 96 F-body that was installed under the prior owner's tenure.
 

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Edit: If it makes a difference, the engine is mostly a rebuilt LT1 from a 96 F-body that was installed under the prior owner's tenure.
What MAF are you running 3" B/D body or 3.5 F body? you could unplug it also, but it should at least start (just something else to bring up). I hate to say opti, but.. I would check for spark with a tester and also check injector pulse. It sounds like fuel or spark is missing both controlled by the computer from information given from the opti (If I remember correctly), it's late for me. I haven't had that issue in over 10 years so I'm not 100% right now.

You really need a data cable for these cars and a laptop with some free software to diagnose correctly and fast.
 

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Discussion Starter #3 (Edited)
What MAF are you running 3" B/D body or 3.5 F body? you could unplug it also, but it should at least start (just something else to bring up). I hate to say opti, but.. I would check for spark with a tester and also check injector pulse. It sounds like fuel or spark is missing both controlled by the computer from information given from the opti (If I remember correctly), it's late for me. I haven't had that issue in over 10 years so I'm not 100% right now.

You really need a data cable for these cars and a laptop with some free software to diagnose correctly and fast.

The MAF appears to be the standard B/D body unit. The intake is B/D as well; as best I can tell from what I was told by the previous owner, examining the block and what parts fit it, it's an F-body block with the B/D heads, intake, manifolds, accessories, etc. Here's some pictures of what I have in the car so all can see what I'm dealing with; these are from previous work on the car.













I have tried starting with the MAF plugged in and unplugged and nothing changes.



I checked spark with a timing light and with a spark tester - it is firing. Whether it was firing in correct time, no idea... Here's video of the testing - please note that any 'misses' are due to the camera's capture/refresh rate. You can see some of the 'missing' flashes magically reflected in the water bottle.


Timing light connected to coil:



Timing light connected to third cylinder on driver's side bank.


Have not yet checked for injector pulse with noid lights as someone has borrowed my noid light set and not brought it back. However, I can hear the injectors click via mechanic's stethoscope, there is a scent of fuel coming out the tailpipes if it is cranked for a long time and there do seem to be fuel/air explosions happening as the exhaust manifolds do warm up in spots corresponding to some of the head exhaust ports.


I will have better access to the car over the weekend - it was initially towed to a friend's house as that was the closest spot within the initial AAA tow radius. It's now being towed to my place and I won't have to make 40 mile round trips to work on or diagnose it. Once it gets here I'll try to pull codes again but I didn't have any codes last time I checked (this was before I accidentally nuked the original PCM as mentioned in the other thread. :/ )
 

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I know you'll feel better when you get it back to your place for some more methodical diagnosing. You say it sometimes catches for backfire, but from just one of those vids it sounds 100% like no fuel. Did you try spraying fuel or ether in to confirm/eliminate that angle?

I replaced a fuel pump and ran fine - for 3 days. Then dead. Dropped the tank again and found harness wire with loose connector. Crimp it tighter and all better since. So sometimes it's the last thing you did that is the source of the issue.

Outside of google do you have a FSM for their diagnostic trees?
 

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Discussion Starter #5
If you watch the first video all the way through, you’ll hear in the last third where the engine is popping through the exhaust. Have not sprayed fuel or starting fluid in as of yet as neither was available where it was at.

Do have an FSM and have been consulting it to little avail so far.
 

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Did you get it back home yet?
 

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Did you get it back home yet?

Not yet. Due to it being Memorial Day weekend, the towing services were quite backed up and couldn't do it in the window available. It looks like we'll try to get it over here on Tuesday or Thursday.
 

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Managed to get it home despite a comedy of stupid on the part of the tow company. Where does everyone suggest I go look first?
 

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Me? I'd go after regular maint. parts that I can't personally vouch for being less than 10 years old. The car deserves that much basic respect in any case, and it might accidentally improve or fix the glitch. Boring and obvious junk that takes relatively little time like EGR (if testing shows weak or broke), fuel filter, maybe that temp sensor in the waterpump that causes all kinds of horror when it goes wonky. ICM, IC and on and on....



Of course I'd test the hell outta the FPR and that fuel pump/harness that got installed recently.
 

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That sounds suspiciously like ‘randomly throw parts at the car and pray something fixes it.’

The FPR is over a year old and is holding pressure fine. The fuel pump and wiring replacement were done after the car stalled and failed to restart; likewise they have tested fine. The ICM has been tested and passed repeatedly. The fuel filter isn’t clogged (see above testing) and is less than two years and 20K old. What is this sensor in the water pump you’re talking about called?
 

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Some parts are so cheap, and so easy to replace, I almost don't mind throwing those parts at it. Almost.

In the 3rd post, I see moisture stains on the main pulley. If your Opti-, your -Spark, or both are corroded by antifreeze that got inside of it, that could contribute to, if not cause your issues.

Sparkplugs, Sparkwires, Vent & Vacuum Harness, Coil, Driver Module, all very cheap, and with the exception of the plugs and wires, easy to replace.

The H2Opump is not terribly expensive, but it is a tedious pain in the arse to replace.
If the little weephole at the bottom of the H2Opump is weeping, AND you're having ignition issues, might as well replace the H2Opump AND the Opti-Spark (and pretty much all the other seals & gaskets in that area that show any signs of leakage) simultaneously.
 

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Discussion Starter #12
Some parts are so cheap, and so easy to replace, I almost don't mind throwing those parts at it. Almost.

In the 3rd post, I see moisture stains on the main pulley. If your Opti-, your -Spark, or both are corroded by antifreeze that got inside of it, that could contribute to, if not cause your issues.

That picture was from last year when we had to change the upper radiator hose, what was there was some spillage when replacing the hose that didn't get mopped up.


It did have a problem where it was dripping a bit out of the bleeder bolt when cold and pooling on the side of the water pump for a bit, but that was taken care of within a month of occasional operation and it didn't seem any worse for wear - this was at least four months before it died in traffic. It has never shown any signs of leaking from the water pump weep hole, which we've checked regularly. I do agree that this could contribute to Opti failure. What I'm looking for is a diagnostic I could use to confirm that it is the Opti before I have to rip the front end of the motor apart to replace it in the height of Texas summer heat. :p



Sparkplugs, Sparkwires, Vent & Vacuum Harness, Coil, Driver Module, all very cheap, and with the exception of the plugs and wires, easy to replace.
IIRC, the vent/vacuum has already been replaced. The coil and ignition module have not been replaced but they both have passed repeated testing. Plugs and wires are an unknown at this point but I wouldn't think the car would just have completely shut down all of a sudden without prior rough running or other issues if those were at fault. That said, we're looking at replacing them on general principles once the car is back up and running.


The H2Opump is not terribly expensive, but it is a tedious pain in the arse to replace.
If the little weephole at the bottom of the H2Opump is weeping, AND you're having ignition issues, might as well replace the H2Opump AND the Opti-Spark (and pretty much all the other seals & gaskets in that area that show any signs of leakage) simultaneously.
Water pump isn't weeping, leaks were cleaned up months ago as mentioned above. We have a Gates water pump and FelPro gasket set coming this next week - having looked at what's involved to get to the Opti, it's just like on certain other vehicles - you have to pull the water pump off to get to something or do almost the same labor to get to it, you might as well replace it. (Thinking Nissan VG30/33 V6 engine off the top of my head.) Is there any test that can definitively confirm that the Opti has given up the ghost or is sending erroneous information?
 

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That sounds suspiciously like ‘randomly throw parts at the car and pray something fixes it.’

........What is this sensor in the water pump you’re talking about called?

Not at all suspicious and you're right. lol But I can't recall how many times I've caught (caughten?) something else while working on a completely different item nearby. It sounds like you've thrown a lot of diagnostic testing in the mix v. my approach just to get the comfort in keeping up with the expected maint. whenever possible (with only quality replacements mind you - or else could actually lose ground).


And it's the ECT electronic coolant temp sensor in the WP. It, and its connector, have caused no-starts along with the oil level sensor. But that may have already been posted IDK
 

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And it's the ECT electronic coolant temp sensor in the WP. It, and its connector, have caused no-starts along with the oil level sensor. But that may have already been posted IDK

I don't think either of those have been mentioned. Is there a test procedure for them in the FSM?
 

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My unofficial test procedure for the Coolant Temp Sensor [as well as the vast majority of electronic wires & wiring harnesses] is to gently wiggle the connector, & the wires, as if to see if they're already damaged.

The vast majority of the wiring is one gauge too thin.

Several years ago, I noticed that if I kept my foot on the brake while entering turns, the engine would threaten to stall.
Took a few months before I found out about an intermittent issue with the bundle of wires that runs over the left side valvecover. All I had to do was wiggle that wire bundle, or keep my foot on the brake entering turns (basically the same thing), to expose my wiring issues.

Goes without saying that your mileage may vary.
 

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I don't think either of those have been mentioned. Is there a test procedure for them in the FSM?

There is likely some flowchart in the FSM. I've got one, but often found more smarter and straightline practical tests in searches here. Both those specific items have testing methods in threads I've come across from poking around. VOMs readings with KOIO and when running and suchlike.
 

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Thought I'd finish this off for the archives.


A number of circumstances (business/job plus city code enforcement and issues with the rest of my vehicle fleet) conspired to force me to farm out the job, despite having collected all the parts needed to do it. I simply didn't have the time to deal with it. I had to have it towed to an import dealership a friend of mine works at to have his ex-GM-tech co-worker repair it as a side job. We did replace the coolant temperature sensor with a Delphi unit.


The problem did turn out to be the Optispark. Replacing it solved the no-start condition. We then found out the engine had a plugged cat and some drama came of that but at this point the car is having the plugs and wires replaced and should be returned to me this Monday.
 

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Thanks for checking in

Ah sssooo, the 'ol Opti thing. Please post the brand used as some names are going through quality issues. I'm sure you've heard of the "mis-clocked" sensor wheel problem, and with a '94-95 it won't show as a code.


And clogged cat? I'm going to go searching here to find out how that happens. O2 sensors might be a good maint. item after such an issue. Conventional wisdom is ACDelco only, Bosch is poo-pooed by many.
 

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Discussion Starter #20 (Edited)
Ah sssooo, the 'ol Opti thing. Please post the brand used as some names are going through quality issues. I'm sure you've heard of the "mis-clocked" sensor wheel problem, and with a '94-95 it won't show as a code.


And clogged cat? I'm going to go searching here to find out how that happens. O2 sensors might be a good maint. item after such an issue. Conventional wisdom is ACDelco only, Bosch is poo-pooed by many.



No idea what brand of Opti it was that failed; no visible makers' marks that I recall (I've seen the part off the car but the part and the car are not here at the moment) and it was on there when we got the car. It clearly was aftermarket, not original GM. I've got a thread over here detailing what was to be put on the car as replacements: https://www.impalassforum.com/vBulletin/34-engine-problems-maintenance/1313370-changing-optispark-do-i-have-everything.html

The cat was detected as clogged when the mechanic finished swapping the new water pump and Opti on then discovered the driver's side cat was glowing red hot within a couple minutes of starting. One replacement MagnaFlow universal cat later (O'Reilly lists the wrong one in their computer index, correct one is number 91004) and the problem was solved. Unfortunately, one of the plug wires came adrift for reasons unknown and melted on the driver's side exhaust manifold, so the tech is having to fix that. I did inspect the removed cat and it was pretty much solidly plugged.

Catalytic converters of this era weren't all that great at self-cleaning so they do eventually wear out or plug up (and certain oil reformulation changes didn't help, which is why recent reformulations have changed it so the oil is less toxic to catcons - sometimes at the expense of protection) - the ones in this car were 230K old. The oil thing is germane because the actual owner of the car tends to drive it, er, 'spiritedly' and the first few months he drove it, it had 5W30 in it and we were getting some blowby/vanishing oil. Since corrected by driving less enthusiastically and going to 10W30.



We're probably going to have the passenger catcon replaced soon on general principles. The O2 sensors are also probably on the replacement list.
 
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