Hot start problem, Checking opinions before I buy a new battery Options

[Highland]

My car starts easily when cold, but hot it has been a struggle. I put a variable resistor on the CHT as an experiment without success. Engine's not even catching.

Plugs look good, 123 distributor, blue coil, valves adjusted, runs fantastic once started.

I am using a 2 year old motorcycle AGM battery(which has been working prior to 123 distributor install). Open voltage measures at 12.6V.

I stuck a lead on the coil while cranking and voltage drops to around 10V and will bounce down to 0 occasionally if I crank for more than a few seconds. With ignition only the coil is at about 12.3V.

The blue coil is an NOS coil that I had. It's probably over 30 years old but resistance is good when cold. I did not think to measure the resistance hot, but would it make a difference? Does the insulation breakdown over time even if resistance is good?

Thinking my little battery doesn't have enough power to crank and fire the coil. Any opinions? Cranking is strong.

[emerygt350]

If your cold start is bypassed I wonder if something else is mucked with or broken to get you a good cold start which then bites you in the rear on a hot start.

Are you sure everything is kosher on your fuel injection system? Above you mention a 123dizzy. Is that still the case? Is this a 2.0 or 1.7? What year is it?

[Highland]

If your cold start is bypassed I wonder if something else is mucked with or broken to get you a good cold start which then bites you in the rear on a cold start.

Are you sure everything is kosher on your fuel injection system? Above you mention a 123dizzy. Is that still the case? Is this a 2.0 or 1.7? What year is it?

The car is a stock '73 D-Jet 2056 cc. FI is all stock. The cold start sensor is hooked up electrically, I just don't have a fuel supply going to the injector. Based on the activation temperatures, I don't think it would make a difference in SoCal, but electrically everything is connected.

I have read Brad A's analysis and that's the first thing a tried with a variable 2K resistor. I'm just wondering during starting how the ECU controls fuel output. Is it just CHT and fuel pressure? Is it taking MPS input during cranking and would that be the equivalent of nearly full throttle?