Hello all. I hope someone can point me in the right direction. I have this 240z I’m trying to get running and am having a bit of trouble getting it to run. The car will start and then sounds like it runs just fine but does after about 20 seconds of running and then will not start again unless I let it sit for an hour or so. 
my first thought was rust in the tank causing poor fuel delivery. Fuel was an orange color in the filter. So this morning I ran the fuel feed line in a clean jug of fuel to bypass the tank all together (electric k&n fuel pump). This caused the same outcome. Started and sounded good for a short moment, then dies and wouldn’t start again. 
could someone possibly point me in the right direction to diagnose?

thanks in advance to any constructive help

Edited June 27, 20213 yr by Dcreech0

When it starts to die shoot a bit of starting fluid into the carbs to see if it will keep running. That will narrow the problem down to fuel delivery. If you have SUs check all the filters including the banjo filters on top of the float bowls.

I do have the su carbs still. Just pulled them and did a work bench cleaning and reassemble. I did clean the mesh screens on the banjo bolts well with carb cleaner

If it will run on starting fluid, I'd check the float levels after it dies. Pull the domes and pistons and raise the nozzles to the top. Then lower them app. 9 1/2 turns down. The fuel level should be at or near the top of the nozzles. That will confirm the fuel levels are 3/8" below the carb bridges. Raise the nozzles back up to app. 2 1/2 turns down from the top.

One thing to note also. After the car stalled I opened the drain plug on the float bowl and it was totally empty. Would this confirm I have a fuel delivery problem?

It's definitely a fuel delivery problem. I'd start at the fuel pump to see if it is pumping with the key on.