Car stalling AGAIN, Updates- none of them good. Options

[rjames]

Drove around for 30 minutes in 80+ degree weather. All arterial roads, so several stop lights, etc. No problems until I was almost home. Car stalled when I stopped at a light. RPMs just dropped to zero. Was able to start it again with a little difficulty and had to keep my foot on the gas to keep it from stalling out again. Power seemed ok though the rest of the way home (I think). It stalled once again at a stop light a couple of blocks from home and then again when I pulled in the driveway. I let it sit for 30 seconds, started it again and it idled just fine. Rock solid at 1000 RPMs. Pulled it into the garage where it sits now.

Prior to today the car has been running and idling perfectly since I went through the FI parts last year, which included installing a 123 distributor, new CHT sensor, a newly rebuilt mps (calibrated for correct afr on my engine), new vacuum hoses, NOS throttle body, rebuilt injectors, new fuel pump, valve adjustment and timing.

I haven’t checked the AFR since last year, not sure why it would change though.
It’s a ‘75 so the fuel pump is in the front, so I can rule out vapor lock I think.

Anyone have ideas as to why it would be stalling?

[BeatNavy]

Robert, sorry this issue has resurfaced (IMG:style_emoticons/default/sad.gif) It's either so obvious it's staring us in the face or buried so deeply we can't find it among the usual suspects.

Those are good suggestions about the relay board. Is that in good shape? It's a little tedious, but since you've tried just about everything else, you may want to remove the relay board from the car and test continuity between the traces. As a minimum once you remove the relay board you'll see the multi-wire ground in front and below the board that it's connected to. Worth cleaning, inspecting, tightening, etc.

Not long after I picked up my '72 I went through the whole D-Jet. The relay board was suspect, so I removed that for some TLC. While I was at work my wife actually took the time to scrape all the tar off the back with a bucket of solvent so I could inspect and repair. Nasty job, bless her heart (come to think of it, that may have been the LAST thing she did for me on that car.... (IMG:style_emoticons/default/idea.gif) ). Anyway, I did end up finding some questionable connections and soldering or reinforcing those before sealing it back up again.

EDIT: Sorry, Robert, I realized initially I put a "happy face" in the first sentence. Not my intention. It's changed now in my post (anyway) to a sad face to show that I know this sucks. I'm sure that makes you feel a LOT better.... (IMG:style_emoticons/default/headbang.gif)

[rjames]

Robert, sorry this issue has resurfaced (IMG:style_emoticons/default/smile.gif) It's either so obvious it's staring us in the face or buried so deeply we can't find it among the usual suspects.

Those are good suggestions about the relay board. Is that in good shape? It's a little tedious, but since you've tried just about everything else, you may want to remove the relay board from the car and test continuity between the traces. As a minimum once you remove the relay board you'll see the multi-wire ground in front and below the board that it's connected to. Worth cleaning, inspecting, tightening, etc.

Not long after I picked up my '72 I went through the whole D-Jet. The relay board was suspect, so I removed that for some TLC. While I was at work my wife actually took the time to scrape all the tar off the back with a bucket of solvent so I could inspect and repair. Nasty job, bless her heart (come to think of it, that may have been the LAST thing she did for me on that car.... (IMG:style_emoticons/default/idea.gif) ). Anyway, I did end up finding some questionable connections and soldering or reinforcing those before sealing it back up again.

Good suggestion- you probably can guess how I'm going to answer- I have a stack of 4 relay boards and spare relays. Continuity has tested good on all of them, although I swapped the one in the car out anyway. I will check the ground connection there though, somehow I missed doing that.