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.

[Highland]

I know I'm getting fuel, so I've been focusing on the ignition. Tried swapping to a "cool" coil after a run with the same results. Also cleaned up the ignition wire contacts hoping that would make a difference (at which point I planned to buy a new set of wires).

Should have done this first, but I unplugged the FI trigger points and cranked the motor to look for spark on an exposed spark plug (it did spark). The motor tried to start with no fuel. I tried starting the car with open throttle (set in place prior to running pump) and was able to get the car started. On a cold start I just turn the key and the car starts every time with closed throttle.

So I'm way too rich on hot start. I don't understand what controls pulse length during starting. Aside from the CHT (I did not add a resistor), are there any other controls? Does the ECU see the MPS at full throttle during starting? As long as the throttle is in a fixed position prior to the pump starting, does the TPS play a factor? Does ECU idle knob effect starting pulse length?

My cold start injector is not hooked up and injectors were rebuilt by Mr. Injector so I'd be surprised if all 4 were leaking, but I guess it's possible. The plugs look good with that brownish white electrode color so I think my mixture is okay while running.

So what knobs can I turn to lean out hot start?

[BeatNavy]

So I'm way too rich on hot start. I don't understand what controls pulse length during starting. Aside from the CHT (I did not add a resistor), are there any other controls? Does the ECU see the MPS at full throttle during starting? As long as the throttle is in a fixed position prior to the pump starting, does the TPS play a factor? Does ECU idle knob effect starting pulse length?

is this D-Jet? If so is this a classic hot start problem?

Really, CHIT is the biggest variable. I'm not aware of any "start mixture" control in terms of adjusting pulse width. It's going to be controlled by the usual suspects: CHT, MPS, fuel pressure, and TPS (if you have throttle down the idle mixture knob should be irrelevant).

Brad Anders demonstrated a few years ago that the classic hot-start problem is not going too rich but going too lean. Worth reading: http://www.914world.com/bbs2/index.php?showtopic=298261