Thanks to all that are hanging around this thread to help me out.

I believe this is narrowed down specifically to something with the START circuit only. Everything seems to work as designed when the key tumbler is in RUN. I know I had a couple of issues of odd idling but generally before and after starting with the key tumbler in RUN it's fine.
So I am looking for those that understand the starting circuit sequence or schematics to hopefully chime in.
To recap, it acts like it is basically an insufficient battery during starting (bogging down, dimming lights).
I know when the key is taken to START, power is sent to the solenoid relay, and the ASD relay. The ASD relay powers the fuel system (injectors and pump), ignition coil and O2 sensor. The PCM from what I understand is controlling the ASD relay during cranking when it has a signal from the crankshaft sensor. So what load is being introduced during that START position that's putting that much draw on the system without blowing a fuse?

Second thought is could the battery not be suitable for the load, even if it tests ok. It came with a NAPA legend 500 CCA/600 CA battery. The other I threw in there to test it with as a bottom of the line Oreillys 600CCA/680CA battery. Would stepping up to an 800CCA/~1000CA help?

 

By chance is this an automatic? If so have you checked the NSS?

 

Good question, no it’s a manual. Probably should have mentioned that

 

Stepping up the battery didn’t help either. Got the highest power group 34 I could. It seems to power through the resistance to starting, but issue remains and still had low power when driven

 

Can you take a video of the hard start?

 

Sorry I forgot to get a video. I ended up having to replace the alternator because while checking the connections one of the terminal screws snapped. Still have the problem.
I tested the signal wire to the coil, but not sure what exactly it's telling me. With the positive voltmeter lead connected to the positive(?) of the coil input plug (the outer one) and the negative lead to the negative battery terminal, I get solid battery voltage in ON, and anywhere from 2-5 volts when cranking. With the positive voltmeter lead connected to negative(?) of the coil input plug (the inner one) and the negative to the negative battery terminal, I got a momentary 12.5 V when taken to ON and then a steady 11.2V when cranking.

 

The link above is a video of the starting issue, this is one of the better bad starts if that makes sense. Normally the clatter before it fires is more pronounced and sometimes it won't start. I'm not sure how much you can tell but it seems to run and idle fine after

 

Can you do the same thing but a video from the engine bay area?

 

The first two starts are relatively normal, third is one of the bad ones

 

Man, that sounds like a bad lifter or possibly broken piston. Got any exhaust gas blowing out of your rocker cover?

 

No, not that I can tell. If it was a lifter or piston wouldn't it be consistent? When it starts normally it idles great and runs fine....

 

Possibly not, but honestly it doesn't sound great even on the first start, it sounds rough. DexJs on YouTube has a video about diagnosing bad sounds. That said, if the lifter is collapsing I imagine you'd get a studderd start

 

I still had the old distributor that came on the rig when I bought it. I reassembled it (i had taken it apart with plans to refurb it but just bought a new one instead after seeing prices for the gear, reluctor and camshaft sensor).
After installing it is no longer doing the hard start sequence shown in the video. It still cranks more than I'd like but starts. So I guess the replacement distributor is the source....
I read in a couple of other places the wear of the distributor gear could be an issue, as the corresponding cam gear is also worn to match, so a new distributor gear may not mesh well and cause timing issues. I'm not totally convinced that's the culprit, as I would except consistent poor running issues if that were the case but at least it seems to be starting better.
The original distributor was a "Lucas" brand - is that what was OEM on the XJs?

 

Lucas is what is on my 88. I didn't like it when I saw it, I've had a 2 Triumphs and a MG through the years and Lucas always sucks.