Welcome! Need support, you got it. Or share you ideas and experiences.
The symptom of hard starting when warm is usually a fuel system problem. The carb may also be getting too warm. Is there an isolator between the carb. and the manifold? Systematically check the system from the tank through the filter to the carb - then 'ohaul the carb.
When the engine is hot, The starter does not even turn over or click or anything. Replaced the starter,ignition switch and solenoid with no change in symptoms. That is why I thought that there might be a heat related safety sensor that is locking out power to the starter.
When this happens, you can short across the starter terminals and it will roll over and start.
Has the wiring been modified in any way? You may be correct about a heat sensor but I cannot see any reason for one. These 'computer' operated engines can be a chore.
You are without a doubt at the mercy of SUPRA. The starter circuit apparently is totally controlled by a computer or logic circuits. Problems with sensors have no simple solutions accept to replace them or do a major rewire to older methods. Too bad a basically simple problem (simpler than a fuel system anyhow) must be complicated beyond basic human logic and basic ability to repair. Wonder why they do that!!?$$
Do you have any trouble shooting diagrams for the system or experience with such?
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