Will not start after hot lapping
 

Hey everyone, long time no post.

I've noticed after my DE get's hot, it gets very difficult to start. The hotter it is, the harder it is to start.

I'm still going off the OE water temp gauge so I don't have exact temps, but if it's above "half" on the gauge, it just cranks and cranks without firing.. No relevant codes.

Any thoughts?

You aren't running E85 are you Kevin? That's sort of a known bug with the stuff.

Nah, 91 octane. I tried the rubber grommet that generally cracks on the OEM fuel pump, but noticed the fuel pump had been changed. Seems to be a generic auto store replacement.

Are you running an external oil cooler? Not sure about mods you may or may not be running, but if you're tracking your Z, an external oil cooler is a must. The heat soak on these engines is severe, without appropriate cooling mods to deal with the WOT conditions imposed by tracking the car, expect the vehicle to go into limp mode. Also do not just jump off the track immediately after hot laps and shut-off the engine, you need to do some cool-down laps to assist the cooling of the engine and brakes.

dkmura should chime in here, he has extensive track knowledge on the 350Z.
-Icer

Yes, I have an external oil cooler. I've tracked the car for 2 years and never had it go into limp mode while driving..just won't start back up while hot.

Relevant mods: 5/16 plenum spacer, dual 2.5 to 3" straight exhaust, air box was cut and just threw on a 9" K&N filter.

Done anything that may cause the fuel to over heat?

Weak fuel pump is my bet

Just caught this thread and have to say that DEs are not known to run all THAT hot or have starting problems on track days. As long as there's no NATS issues, I'd concur with terrasmak's suspicion that the fuel pump may be the culprit.

Hot intake air also doesn't help assuming you didn't route the filter outside of the engin bay.

That's what I've been thinking myself.

Is it possible that the fuel could be boiling in the line? I know the Z's fuel lines run right next to the bank 1 (passenger side) exhaust manifold. If you're running aftermarket headers without proper shielding, the heat generated could be cooking the line. But I also tend to agree that the discovery of an aftermarket fuel pump is a more suspect. Typically boiling fuel is a problem for carbureted engines, not fuel injection. As a side note, the boiling point for Gasoline is 104 - 392 degrees F, depending on the octane level and additives.
-Icer

High pressure pump will push past that quickly , but it is possible

Thanks for the input. Headers are stock and still have the shielding. Fuel pump could be it, could also be hot intake temps. Both worth improving.

Scan sensors through obd2 when it's not starting and see what's not registering when it's hot. My guess crank sensor

what exhaust? where does it dump?

how close to the tank?

you may be heating up the fuel in the tank. it was a problem with old foxbody 5.0 mustangs.

do you have anything special wrapped near or around the fuel lines?

Crank or camshaft sensors