timfitz63

Greetings to all! First post on this forum, but was referred here from another forum in the hopes of getting some answers. I tried searching, but didn't turn up anything specific to my question.

I have an '89 Firebird Formula with the 5.0L TPI engine (LB9) and a 5-speed manual transmission. A few months back, the car started running pretty badly after getting up to operating temperature, and at least one of the apparent causes was a failing bulkhead connector on the engine wiring harness:









Obviously, I need to find a serviceable bulkhead connector to replace mine -- or an entire wiring harness. What information I have on the engine harness for this powertrain combination is in conflict, so I'm hoping that someone here can help me sort out the facts.

Some have suggested to me that the engine harness for my powertrain combination is unique, and that I need to find a harness from a similarly-equipped vehicle. This presents me with a real problem, as there were very, very few vehicles equipped with this powertrain combination (approximately 42 Formulas in 1989 model year); I'm sure there were a few other F-Bodies -- Camaros and Trans Ams -- also made with this powertrain combination, but the numbers were not overwhelming in those cases either, so salvaged parts do not seem to be out there in any great numbers for this powertrain combination... And NOS parts don't seem to exist at all; in fact, I've been told that GM dealerships did not stock engine wiring harnesses even when these vehicles were in production. Go figure...

However, the GM part information I've been able to dredge up for the TPI engine wiring harness (part no. 12083626) shows that the harness is transmission-independent for the TPI engines (i.e., it has no leads or connections to the transmission, and therefore, the pin-outs on the bulkhead connector are the same). This suggests that an engine harness from any TPI engine/transmission combination would be compatible with my vehicle. Can anyone confirm that?

Something else that would be useful to know: how hard is it to re-pin a bulkhead connector, if I can find a serviceable one? I believe the bulkhead connectors are effectively universal for the Third Generation Firebirds, but I don't know for certain if I can easily remove the pins from my connector (obviously after noting their positions), then re-pin a salvaged bulkhead connector from another engine harness... Are the pin-outs molded into the plastic housing of the bulkhead connector?

Thanks in advance for any information!

timfitz63

Wow! Over a hundred views at this point with no responses; apparently I've stumped the masses...! Anyone at all have an answer for me...?

85Z28NOS

iTrader: (2)

the bulk head picture you show has both the body and the engine connectors still attached together. I had some trouble with mine a few years ago and just removed the factory tar-like coating and repaired it. As far as them interchanging, you must get one from a MAf car so it will have the correct connectors for your engine. It doesnt matter if its from a camaro or a trans am as long as its for a maf engine

Dyno Don

iTrader: (7)

I don't know what melted that, but yes you can repin another connector.
The tar does get in the way but work around that.
There is a security plastic clip that has to be removed before you can take out the connectors, it's white. Remove that and get a device to release the pins on the connectors.

Here is a picture, that white fork thing is the security clip.
And a tool like I use.

timfitz63

Any suggestions on how to clean that stuff off without affecting the wiring insulation? It's pretty gummy on mine, and when you get it on your fingers, it doesn't seem to respond well to light cleaning solvents like soap...

OK. I've heard that along the way as well. What I'm hearing you say is the harnesses from any MAF-equipped TPI engine, regardless of transmission or model year, are compatible with mine? Is that correct?

I see the tool, but not the clip... But I'll check on mine.

Thanks for the advice, guys! Keep it coming!

Dyno Don

iTrader: (7)

The piece that looks like a fork without a handle.

It's buried in the tar, you will need solvent or gas to remove that stuff.
I pulled it out a ways so you can see what you are looking for.

TTOP350

iTrader: (8)

I would find out which circut is failing and just repair that wire or 2.

timfitz63

Ah, OK. I see it now. Thanks!

That's the basic plan. But the bulkhead connector is kind-of like a piece of candy right now: crunchy on the outside, gooey on the inside... Seriously, it's a real mess in there between the mixture of goop that GM put in there in 1989 and the melted plastic; so before I tear into it to see which wire(s) are the culprits, I want to be sure I can put everything back together again... And based on its current condition, I'm sincerely concerned that this bulkhead connector will not survive dissection; it's been weakened by whatever has been melting it, and if I start even carefully pulling things apart and hitting it with cleaning solvents, I think it will just fall apart...

ZF6camaroZZ4

That connector on the firewall is for like power connections, head lights and such.
The ecm connector would be on the passenger side kick panel..

Anyway. I think I have one that might work, Its a complete wiring harness of a 90 TA.. So that connector should be there, will take a look later today when we get home from work.

Dyno Don

iTrader: (7)

If you want to change the complete harness, you have to have an '89, it is all by it's self.

ZF6camaroZZ4

On this one I have, I dont see the other half of the bay side harness connector.
Looks the same to swap pins on thou..? I dont see why they would one off a connector.... that doesnt make sense. Use the same crap and change pin outs.

robguitargod1

iTrader: (4)

Here ya go man, us LS swap guys found this a few years ago

http://delphi.com/connectors/product...uctID=15492519

Here's the thread it's discussed in

https://www.thirdgen.org/forums/elec...ector-oem.html

Here's where to buy them

http://www.mouser.com/ProductDetail/...iffPvP7Siao%3d

The other male is 12020629. The female is 15492518

timfitz63

Sorry for the delay in responding; for some reason I'm not getting any notification from this forum about new posts to my thread...

That's generally my understanding as well, although I've had some tell me that harnesses from the '88 model year are compatible as well... But everyone here is saying the same as you: '89 and only '89...

Yeah, I'm nearly convinced that the bulkhead connectors are universal; they just have different pin-outs.

I appreciate your offer! But presuming the 'rule' about '89 and only '89 applies, I'd hate to cannibalize a perfectly good harness from a different model year just to harvest a bulkhead connector. Especially considering that...

Dude! You rang the bell! Just tell me which part number (15492519 or 12020629) I need for the engine-side bulkhead connector on an '89 TPI car; at this point, the parts appear identical to me on the Delphi site, but Mouser Electronics shows a completely different connector using the 12020629 part number. Or is P/N 12020629 the smaller bulkhead connector for the non-engine-related stuff...?

robguitargod1

iTrader: (4)

The engine side male connector is actually 2 separate connectors side-by-side. 15492519 is the larger 25 pin male connector and is available at Mouser for $3.52 at the link in my first post.

The other male connector and the firewall mounted female connector are both only available in huge minimum quantities and big lead times........haven't been able to find a place that'll sell only 1.

timfitz63

OK, that's what I'd figured; thanks for the confirmation!

Pity the other ones aren't available in reasonable quantities... I'd thought about buying all three parts, just in case...

robguitargod1

iTrader: (4)

Min quantity on the female connector is 135 @ $6.67 each. So if we could find 135 people that want the connector we're gold!

Min quantity for the other male connector is 400 @ $.80. Anyone need 400?

timfitz63

Well, if a group order is ever put together, count me in for some...

timfitz63

I'm going to be attempting this repair when I get back to San Antonio next week, and have ordered the parts from Mouser (shipped to San Antonio ahead of me, so it's not possible to examine one at the moment). Unfortunately, I never thought to ask this before now: do these replacement C100 connectors also come equipped with the security retainer (for the pins) that "Dyno Don" mentions...?

Based on where the damage has occurred on my original C100 connector, I'm skeptical that my original retainer would be salvageable, if it's even removable. Is there another part that I will need to order in before next week...?

robguitargod1

iTrader: (4)

I can't even tell if the clip is on your connector in the 1st posts pics.....

timfitz63

Yeah, to be honest, neither can I... I've been trying to deal with this problem from afar for about three months now; if you can believe it, next week will be the first time that I get a chance to actually put eyes/hands on the affected parts...

fireburdluvr85

that security clip is on all injected { tpi/ tbi} bulkhead connectors. hit a junk yard for a few.

timfitz63

OK. Well, things are progressing slowly with this repair... I was able to get the connector out of the receptacle, but am not really seeing a lot of actual, physical damage to the connector. So I'm a bit skeptical at the moment that this is really the issue... There is a lot of black 'goop' all over the connector face and oozing out of the back, where the wires come into the connector, which seems wrong. Is is likely the damage is internal to the connector (bad wire; or melted, weakend plastic)? There just dosn't seem to be a clear course of action here...

First question: given that this 'goop' is everywhere, including the holes of the connector, I can't really see anything down in the holes, so I'm a bit stumped about how to extract the wiring (if that's really what I want to be doing, given the apparent lack of physical damage to the connector). From which direction do I apply the pin tool to release the wire from the connector: the face (i.e., pin side, which mates to the firewall receptacle), or the rear of the connector (where the wire bundle meets it)? I would presume the connector face, but again: I can't see anything down in the pin holes.

Second question: WD-40 definitely takes this goop right off of my hands. If I bathe/soak the connector in it, I think I might be able to clear out the pin holes enough to see what's going on. But what about the firewall receptacle? Scrub it with WD-40 and a old toothbrush? What about the mixture of WD-40 and 'goop' that gets down into the receptacle itself? Problem...?

The car definitely runs like crap now, almost regardless of how warm the engine is. Before starting this endeavor, I put some fuel stabilizer in the tank and ran it down to the corner gas station to top off the tank; it ran crummy the whole 3-4 miles (total) down and back -- although there were very brief moments where it suddenly seemed to be running fine (momentary power increase and smooth engine operation), but that behavior vanished almost as quickly as it appeared. Most of the time, it sputtered and hacked like it was choking on something...

Third question: Would poor pin connections on this C100 connector really cause this kind of behavior? From the pin diagram that I dredged up, I didn't think there was anything running through this connector that was tied to significant engine functions...?

Anyway, I cleaned it up real well (by now the engine was cool) and ran it around the block one last time prior to putting it into the garage for the duration of this repair effort; it stalled about 4 times just in the 1/2-mile trip around my neighborhood.

Any insights and suggestions are appreicated!

timfitz63

Fourth question: How do you get that white retainer out of the connector? I finally uncovered mine, buried under a pile of 'goop.' I've tried to pry it up, but am not having a lot of success. Is there a 'secret' release on it? It's entirely possible that it's just glued in there by all the 'goop,' which is obviously taking a while to scrape away, even with the miracle of WD-40; but I just want to be certain I'm not missing something.

timfitz63

Well, I managed to answer all of my own questions. And I spent the better part of my most recent trip to San Antonio trying to get this car sorted out. The good news is that, when I was finished replacing the C100 bulkhead connector, everything worked like it did before I started; the bad news is, when I finished, everything still worked like it did before I started. No difference in engine behavior...

To be honest, I began the whole endeavor of swapping the C100 connector with a dose of skepticism; once I pulled it off the bulkhead receptacle and began examining it first-hand, I realized there wasn't any actual damage to it. Everything that seemingly appears bad in those initial set of photos is simply the black, tarry 'goop' that GM apparently used as a moisture sealant back in 1989. A lot of it had oozed out of the connector over the ensuing 20+ years, but the connector itself, save for a tiny bit of warping, was completely intact. But, even after confronting my mechanic with my findings, he was insistent that this was the problem. I had a new C100 connector and some WD-40 in hand, so...

After two solid days of painstakingly cleaning off excess 'goop' so I could extract each individual pin/wire combination, then clean that off thoroughly before returning it to its proper location in the new C100 connector -- all the while negotiating the 2-3 inches of wire lead with which GM had left me to work, and the tenuously-balanced frozen dinner tray I was using to catch the mixture of WD-40 and 'goop' before it trickled down into my nice, clean engine compartment, the only thing I'd really managed to accomplish was to acquire a collection of mosquito bites on my feet and ankles (yes, San Antonio has mosquitoes year-round -- and they're persistent little buggers too)... Eh, well; the good news is I didn't spend somewhere between $300-900 on an entire engine wiring harness for this car, only to discover that that probably wasn't where the problem was... And I saved an equal amount of money (~$900) in shop labor by doing it myself when my mechanic balked at performing this connector swap...

So, I'm back to 'square one.' The $64,000 question is: what defect can cause the operation of an LB9 engine in an '89 Firebird to progressively degrade as the car heats up, but not throw an engine code/SES...? I've all but ruled out engine sensors (including the MAF) and their associated wiring; the ECM would detect that fault and react accordingly. Plus my mechanic checked sensor communication with an old diagnostic tool he was able to dredge up; he also swapped the MAF with an allegedly new one, and like the new bulkhead connector, it made no difference. That doesn't mean there isn't another electrical anomaly (e.g., broken wire), though; I've had a suggestion that perhaps even my relatively-new (~4-5 years old) spark plug wires could be compromised because they were improperly routed (by another mechanic in Waco, who did that work) in the vicinity of high-heat sources. For that matter, the plugs themselves could be bad or fouled, although I tend to doubt it (~4-5 years old). Distributor is new, so that should be fine. Fuel pump going bad...? Injectors clogged/bad...? Clogged fuel filter (also relatively new; ~4-5 years)...? Evil spirits...? Maybe I just need a priest rather than a mechanic...?

Not sure where to turn to get a real solution; I may have to resort to the inelegant method of throwing parts at it until I stumble on the right one...

timfitz63

Well, I realize the following is a bit off topic, but it provides some follow-up on the possible solution, at least in my case:

I was back in San Antonio during the past week, and managed to find a half hour or so to check the resistance on the fuel injectors. And I've uncovered at least one problem with the car: I've got one injector that's bad, one borderline, and two more that are probably just starting to fail... About half the engine isn't running right due to a fuel supply problem...

The failed injector measured 7.9 ohms -- about half of the 16 ohm specification; one was 14.7 ohms (barely in +/- 10% spec. tolerance, but more than 0.5 ohms difference from the 'good' injectors that read ~16.2 ohms); and two more were in the low 15 ohm range (again, more than 0.5 ohms difference from the 'good' injectors). These are the original, 1989-vintage injectors, by the way -- which, according to my research, are not very E10-friendly...

So, I'm looking at replacing all of the injectors; I figure the four 'good' ones can't be very long for this world... Is this task (fuel injector replacement) a relatively simple DIY or best left to the professionals? And any suggestions on what injectors with which to replace these originals?

fireburdluvr85

Sounds like what my 89 engine did. Ohm them hot. Ull find more failed. I had 15 across the board cold but hot 2 @ 4.9. New south bay injectors and mine runs like a top 2 years later.easy job

timfitz63

If I'd had more time, I would have done them after warm-up. But I suspect that you're correct; the engine runs passably when it's first started, but progressively runs worse and worse as it warms up to operating temperature. When it gets warm enough, it won't run at all...

Thanks for the source tip! I'll look into it!