SteveJ

You're not posting too much. You are providing detailed observations. From this I can look at the wiring diagram and try to find some things for you to look at. Did you strip off the wrapping around the wiring harness, or was that the work of a previous owner? From picture 1, I can't tell if those are factory splices in the background. From picture 3, is that the end of a wire that has been cut? From my previous comment, it sounds like someone was trying to fix something and may have introduced a short. Just wild speculation, but it may be that the power for the second fuel pump relay coil or the fuel pump itself gets shorted out with the reverse switch. The car dies (and the damaged circuit loses power) before a fuse or fusible link is blown. If you can get under the car easily and access the reverse switch on the transmission, take it out and see if that resolves the car dying when going into reverse. Also while you're under the car, see if either side of the reverse switch has continuity to ground.

I also don't like how the fuel lines ended up at the TBI adapters. Look at the bend in the line at the front throttle body. (I almost typed "carb".) Rick confirmed the fittings are 1/8 NPT, so I ordered 1/8 NPT to 6AN 90 degree elbows. Then I'll put another 90 on to point to the fuel rail. Hell, I have plenty of braided hose, still.

First verify the battery is good. A bad battery or charging system with the accompanying voltage drop could account for some of the issues. Get the battery load tested. Don't try running the car with a low battery. You can damage things that way. By the way, what is the battery voltage right now? Check with a meter, not the voltage gauge on the dash. I'll trust a 40 year old Simpson meter. I'm not sure I would completely rely on the 40 year old voltage gauge. Verify the presence/absence of spark with an inline spark tester (https://www.harborfreight.com/90-in-line-spark-checker-63593.html). Have someone crank the ignition while you watch for spark. Do this in a relatively dark setting. Again, look for wiring modifications from a previous owner. Search on this site. I know I have provided diagnostics for the 78 fuel pump relay and even described how to bypass the relay for testing.

It's a late 80's/early 90's GM EFI system, so I would any self learning is limited. I don't recall anything about self learning on the website, either. The fact that I could back off slightly (under load) and get the car to respond leads me to believe there is some kind of lack of fuel for a brief period...that and the bucking.

Let me be frank here... You'll need to supply a LOT more information to get decent responses (and not have someone posting pictures from The Naked Gun). You found a splice you didn't like, but you don't say what wire was spliced (the colors are important), how it was spliced, or where the foreign wire went to. That splice may have been one of those "fixes" a previous owner did to work around a problem instead of diagnosing it properly. It is challenging to track the history of the issues. When did each issue start? You added things about the dash light and fuel pump. When did you remove the splice? We cannot see your car, so you have to paint a picture with words (and post photos). If you have a half decent camera on your cell phone, there's no excuse for posting without photos.

You have text message exchanges like this:

With the behavior you described, it's likely one of two scenarios. There is a problem, possibly with the ignition switch, and what you perceive as triggering events are just coincidence. A previous owner has hacked into the wiring to "fix" problems. You might want to pull off the steering column cover and start looking for splices.

Well, I took it for the first test drive. It ran, but it did not run well. At times it seemed like it was fuel starved. I'm going to re-orient the fuel pump to see if that helps some. The plugs were fouled, so I replaced them. The car does not like to idle. I opted to add an Idle Air Control Valve in case I added AC later. I just ordered all of the parts I believe I need to install the IAC valve. I let Rick Patton know the results. I haven't tried to datalog anything, yet. That might happen tomorrow depending upon how well the fuel pump repositioning goes.

The cables are going to the same place they went to on the SUs. They still move the butterflies. I don't know enough about how the GM system works in actual GM cars to know how the throttle body/fuel injection accounted for cold start conditions.

It doesn't matter how big and strong you are if you don't have a way to get leverage. Fortunately I know 50 ways to love my lever.

But did you find my spring?

So when I got home this evening, the first thing I did after exchanging pleasantries with SWMBO was open up my Amazon boxes. I found the spray can of Kroil, and went out to the garage to spray the plug on the O2 sensor bung. I changed into car working clothes (Very redneck chic, I might add.) and went back into the garage. I sprayed the plug again, and then I pulled the car out of the garage (under its own power) and got it up on ramps. I looked at the access to the plug on the O2 sensor bung. It was too tight for the impact gun. The breaker bar would have to work. I got the socket on the plug, but I realized that I just couldn't get the right leverage. So what's the solution? Of course, it's a 2.5 lb hammer. I forcefully tapped on the breaker bar, and I finally saw it turn! I re-positioned the breaker bar and got another 1/8th of a turn or so. After a couple of more small movements, I decided that I didn't want to be using the breaker bar until midnight. I paused and sprayed some more Kroil on the plug. Then I fetched the long handle ratchet and put it to work...only it has a shorter handle, so I lacked leverage. So what's the solution? Of course, it's a 2.5 lb hammer. I tapped the handle of the ratchet, and it started moving the plug. I kept getting the ratchet to turn. Either the head of the plug was going to break off, or the plug was coming out. I did a quick check to verify that the plug was coming out, and soon it was done. I coated the threads of the O2 sensor with anti-sieze and installed it. I connected the O2 sensor and got the car running. It runs a LOT better with the O2 sensor installed. I reattached the choke cables since I found I still need them when the car is cold. I have the throttle bodies adjusted, though the idle is high. On the other hand, the idle was high with the carburetors, too. Now I need to button things up and pick up a $4!+load of tools scattered about in my garage. Then I can do a test drive.

Glad to help. By the way, if you find the spring from my hazard switch, let me know.

I last did this about 16 or 17 years ago... I unplugged the switch from the dash harness. Then if memory serves, I had to push and twist to remove the knob. I took a pair of long nose pliers that had a very fine point on the ends of the jaws and used those to unscrew the retaining ring. Then you have to figure out where the hell the spring went that supplied tension to hold the knob onto the end of the shaft. When reinstalling, you have to curse like hell trying to get the optical fiber back in place to light the knob.

It wouldn't be the first time that box was dumped, and it holds my solderless lugs, too. Instant game of 52 card pick up.

Hmm, I wonder if I'll have enough time... I'm not sure whether or not I used anti-seize on the plug in the O2 sensor bung. It will take a while to get it out. Just in case, new bungs have been ordered.

It's alive. IT'S ALIVE!

Unless it's a diecast or plastic model, I don't think a Z is going to fit on top of that bench.

Well, I found a couple of crossed wires, and it will run the fuel pump like it should. Now I have to get the TPS adjusted (in part by using the right cover) and figure out how to break loose the plug on the O2 sensor bung. There's an outside chance I will have it done in time.

I'm planning on being there...provided I can sort out the fuel injection by then...

I might know a thing or two about the electrical system if you need help sometime...

License plate lamp housing. All of the ones I have found used have been warped all to heck.

@MikeI would agree that's a spammer in waiting.

The strange thing is that the same username is over at Zcar.com with similar types of posts: https://www.zcar.com/search.php?searchid=50972

Why would you put the fusible link between the circuit and ground? Now go back and check post #2. Go to Blue's collection of tech tips for the wiring diagram or search here for a color copy of the wiring diagram.