Just bought a 92 lexus sc400, drove it 2 hours from my house, everything seemed to be fine but later that night it seemed to not want to start, and now since it has been going on for 2 days now it seems to only start when the car is cooled down or hasnt been driven in hours, what could be causing this issue?

 

Is it cranking at all? Does it fire up, idle rough for a bit, then die out?

 

its cranks but dosnt fire up.

 

I was having similar problems, except mine would fire up, idle really rough, then die out. I ended up bypassing the fuel pump ecu and so far...so good. Cant say my advice holds much weight, but its worth a shot...

 

there is alot more problems with it then what my wife said, there is no check engine light present which means 1 bad grounds(most likely because its a intermittent problem) 2 bad ecu not really thinking that if I can get a check engine light to come up on start up I can pull codes, 3 something is pissing my ECU off and its causing it to not have power waiting to go to school so I can get a full wiring diagram and start playing the trace game... I had codes 13 no # 2 RPM which is cam and crank sensors, and code 31 which I caused last night. Ive noticed the car when I can get it started is running rough and really rich black smoke coming out the exhaust and that wonderful smell of money going out the tail pipe almost like a old school disel the same effect while driving it so something is majorly off , not positive but Im thinking its a ground for the ECU because random things will get it to kick back on like slamming the door or the trunk or even the hood ive had all 3 kick the ECU back on

 

Whoa. Cant help ya there...
...free bump though...hopefully someone can chime in and give some input...