I am working an 1990 LS400 that my kid bought. It won't start. I've replaced the ECU, Fuel Pump, pulled all injectors, cleaned and revealed, and reinstalled, I've done a full tune up. Anyone got any ideas?

 

What's the symptoms that you have? Like does it crank with no start or is it just turn the key and nothing? Did you try pulling the codes to see if there is any?
http://www.lexls.com/tutorials/intro/codereading.html
Was there any work done to it before your kid bought it? If so, that might put ya in the right direction to whatever they did last.

 

it cranks but no fire. The guy she got it from said it sat for like 6 years. He said he did quite a bit of work to it. When she bought it, it ran not great but ran. It idled rough, stalled out, didn't shift smoothly, hard to start.

 

Those symptoms point toward either jumped timing or the ECU. As for the ECU you replaced, did you have it rebuilt? Did you or the previous owner do the timing belt? Either way, you should check if ALL the timing marks line up. If it's one tooth off it will run bad but if say two or three teeth off, sometimes it wont start at all.
http://www.lexls.com/tutorials/engine/timingbelt.html
If that's all good then I think you're gonna have to just start with the basics and go from there. Checking if you have spark at the plug wires. If not then going backwards from there, distributor caps and rotors, coils and checking to make sure you're getting fuel.

 

Is it getting spark at all?

 

what ECU did you replace it with? the ECU is known to have bad capacitors so if the replacement ECU never had it's caps replaced, then you're still back to square one.
https://www.clublexus.com/forums/ls-...capacitor.html