I converted to electric fuel pump in my '71 Z and left the return fuel line in place. I figure this helps keep the fuel cooler because the heated fuel that doesn't get used in the carbs is returned to the tank which is cooler than the engine bay. I figure this allows more cool fuel from the tank to flow to the carbs. Also if it's available in Panama you should run ethanol free gas. The ethanol free I use is 88 octane and the car runs just fine. If you don't have ethanol free you should probably run premium. I do have ceramic coated headers and the heat shield under the carbs and I've seen my temp gauge get up to close to half way between the middle of the gauge and the hot side and didn't vapor lock. The weather here runs in the 90's (Fahrenheit) to 100 in the summer. As you've experienced, heavy traffic with lots of idling will heat these cars up!

6 hours ago, w3wilkes said:

I converted to electric fuel pump in my '71 Z and left the return fuel line in place. I figure this helps keep the fuel cooler because the heated fuel that doesn't get used in the carbs is returned to the tank which is cooler than the engine bay. I figure this allows more cool fuel from the tank to flow to the carbs. Also if it's available in Panama you should run ethanol free gas. The ethanol free I use is 88 octane and the car runs just fine. If you don't have ethanol free you should probably run premium. I do have ceramic coated headers and the heat shield under the carbs and I've seen my temp gauge get up to close to half way between the middle of the gauge and the hot side and didn't vapor lock. The weather here runs in the 90's (Fahrenheit) to 100 in the summer. As you've experienced, heavy traffic with lots of idling will heat these cars up!

Well in Panama we have 91 and 95 octane ethanol free gasoline. My car has the original manifold. I only have heatshield installed under the carbs. Maybe its time to consider ceramic coated headers. Thanks for your advice.

Faulty PCV valve? Not surprised. The quality control for these 'consumable' automotive parts is atrocious (spark plugs may be the only exception). They can cripple a car's performance, but spotting a defective item is difficult. You really need to install your 'tune-up' parts one at a time. If the car's performance collapses, you know you've just installed a new-but-defective part. Moral: Buy only the best -- even though they're just 'routine maintenance' parts. Even then, be alert and be suspicious. The auto business is a low-margin enterprise. Even name-brand 'replacement parts' manufacturers have to skate close to the edge in order to keep their shareholders happy. p.s. They do a much better job when it comes to supplying parts for new cars b/c now there are new-vehicle warranty costs involved and their customers (the auto manufacturer) will pay more to keep those costs under control. In the auto biz, it's all about $$$.

I will defer to others when it comes to your fuel pump circuitry. My thesis is all about making the system (your engine, along with its fuel and electrical systems) as simple as can be, so that problems much easier to diagnose. Once that's done, you can add back the complexity (emissions control equipment) as you see fit. If it were me, living in Panama and driving a carbureted 50-year-old classic, I'd limit that to the PCV system. All the rest of the 240Z's emissions control gear, viewed from a 2025 perspective, is -- not to put too fine point on it -- finicky crap.