2001 2.4L frontier won't start when hot

How old are wires? Plugs? Clean out EGR valve. Also check your Coolant temperature sensor. Any check engine codes? Throttle body dirty?

No codes. EGR valve was cleaned. Cap and rotor are not very old. Runs great until hot, then stalls and won't restart. Will restart when cooled off, about 2 hours.

Have you tested crank and cam sensors? A sign of one of these going bad is intermittent functionality. Have you tested resistance of each plug wire? There are good YouTube videos how to do this. With them being close to engine heat they will lose the ability to let electricity flow. It is simple.

Have you tested fuel pressure? Hot and cold? Failing fuel pump relay when hot?

Have you done a visual check on your ignition coils? Tested them? Any cracks in shielding or score marks inside plug wells?

Was hoping this was a common problem. Am gonna check the injectors with a noid light, then if good see if I have fuel pressure. Clearly it does when it's running, but something happens when it gets hot. Fuel pump has been replaced about a year ago. As I said, please note, all is fine when it cools off.

After that, I'll see about the crank sensor, which is hard to get on this vehicle.

Do the easy first I would go after the fuel pump relay 1st then check coils and wires. Did you say new plugs? I have seen many intermittent relays. Again many videos on how to check these. You can also swap relays if you have an exact one in the fuse box. Just make sure it is something you might not need if it cuts out Like the Horn relay for example.

Noid light says I have injector pulse. Also have spark. So, must not be getting fuel pressure. I can actually idle it in the driveway like I did tonight for about 30 min, running fine, shut if off for 2 or 3 minutes, and it heat soaks to where it won't start again. Could be fuel pump relay, but I doubt it since it's inside the cabin in the a/c. I thinking maybe crank sensor or cam sensor. Cam sensor is in distributor, as is the coil, so would have to replace whole thing. $250 for aftermarket or $350 for Nissan part, so that will be what I try after cheaper things like a crank sensor.

Also, remember I said I have spark even when it won't start, so not likely the coil. Maybe sensor not telling ECU to turn on fuel pump?

Pressure is hard to test... no schrader valves on fuel rail. Will have to wait until Friday when I can get underneath it and tie into the fuel line at the filter with a gauge.

Also if fuel pump was aftermarket they have a low success rate. I always buy OEM, not worth headaches

I agree, but remember, it starts back up after cooling off. Hard to imagine pump getting hot in all that fuel.

I still think electrical. I was going to ask how much fuel is in tank. Most people do not realize that they should never run fuel below half as it cools your pump. I wish I could test that fuel pump relay for you. :). 2001... a relay could be bad.

Check resistance of all 4 of your fuel injectors hot and cold. Resistance is good cold but out of range when hot shutting car down. I read this is an issue on many cars. Also, I couldn't find any information on this but saw a good video about a car shutting down after an hour and then starting cold. It had a bad "auto shutdown relay". I got on several sites to see if your truck had this but couldn't find anything on your engine, year or make. Many said this is equivalent to the fuel pump relay on a Nissan.

I'm going to try the fuel pump relay next, due to suggestions and it's cheap. It seems apparent I have no fuel pressure under this condition, so something is causing that. Could be injectors, but seems odd they'd all be bad at the same time. Possible though. What about pressure regulator? That's totally mechanical, isn't it?

Put in new relay... no help. Only $12, so no big deal. Ran it til it died, then had the wife turn the key while I opened the fuel cap and put my ear up to it. Didn't hear anything. Waited 2 hours until it would start again and did the same thing. Couldn't be totally sure, but "think" I heard some whirring when she turned the key. So, I'm pretty sure (though not totally) that it's the fuel pump. Aftermarket piece got put in just less than a year ago, so going to take it back to the same place on Friday.

If you can get OEM then do it. I wonder if it I a Denso? I have never replaced a Denso in my Toyotas in 27 years.

Wondering if you fix the problem by replacing the fuel pump!! I have the same problem .I replaced the crank sensor,distributor,pump relay,cables so now I'm going for the pump any advice would be much appreciate it !

Mine did turn out to be fuel pump. Two reasons I didn’t suspect that at first. One, it worked when not run more than an hour or so. I thought a fuel pump either worked or didn’t. Didn’t think it could be intermittent. Second, I had just replaced the pump about 6 months prior, so figured that was good. Replaced with OEM pump, and all has been well since.

Thank you so much for your reply..