gearhead30 - yep. stand alone HEI... I will try and pick up e fuel pressure regulator with a return port this week. I have two fuel lines that run up the firewall by the dizzy. One is hooked up, the other isnt... I assume that is the return line. Should be an easy swap. I need to do that anyway. I am also redoing and cleaning the grounds with new straps and wires to rule out grounds as an issue for the gauges as well.
No other pinging or drivability issues. Runs good till you get in it and it falls on its face or its under load.
Not as worried about the dummy lights for now. Prob deal with that later.
I do need to handle the A/C though... I looked for threads with a HOW TO rewire the a/c out of the computer but came up empty. it is still run through the computer so, what would make it not work if the computer is still in there? is there a connection with what the motor is doing to the A/C for ECM management? Is that why it needs to run stand-alone?
Thanks so far... gets me on the right path. I hate computer-controlled cars but... never liked the dash in the earlier trucks. Now I gotta deal with it on a whole different level with this thing.
There should actually be 3 lines coming from the tank on that truck. Pressure, return, and a tank vent that previously would have gone to the charcoal canister. The other line on the firewall is probably the return though. I'm not sure if the fuel pressure regulator will solve this problem, but it will definitely be a durability improvement since the OEM pump is not designed to be nearly dead headed like that and will live a pretty short life.
No pinging or other driveability issues suggests to me that timing is at least close to correct.
Supercharged111 makes a very good point about the wideband, which may be useful to dial in your fueling anyway. Extremely useful tuning tool that I would suggest you add if you can. Not sure if that carb has actually been tuned or if the previous owner threw it on there and expected it to work.
I don't know what signals the ECM needs to 'allow' the AC compressor clutch to engage, but before assuming it is the problem, it would be good to make sure the AC system is actually charged correctly. Nothing works if it isn't correctly charged.
If it is charged, there should be a mechanical low pressure switch and a mechanical overpressure safety switch. I believe overpressure is on the back of the compressor and low pressure is on or near the receiver drier on the passenger side firewall. Both of these need to be hooked up and working. It has been a long time since I've troubleshot them, but I think both of the switches are closed (i.e. have continuity) when they are in range. If they are out of range, then they open and prevent power from reaching the AC clutch.
I assume you have a multimeter so you can check this stuff, but if not, it's an incredibly useful tool that's worth spending a few bucks on.
If you are 100% sure that the rest of the AC system is correct, the LAST thing to check would be briefly jumping 12V to the compressor clutch pin to make sure it is working properly. This bypasses any controls and safeties in the system, so you want to do it only for a second or two. Running it without proper refrigerant charge will kill the compressor quickly, and if it is overcharged or there is a blockage causing extreme overpressure, you could easily blow something up and injure yourself. Hence why there are safety switches.
If you can find a wiring diagram for the AC system, it may make it easier to troubleshoot and confirm that the ECM has control and doesn't just take AC operation as an input.