I am going to suggest the fuel sending unit to my dealership. Also, does anyone know how warranty's work? Mine is an 09 and has 16,000 miles on it. 2012 is approaching. Will they not do the warranty work because it is 3 yrs different, or is it 3 years from the exact manufacturing date?

I don't think the fuel sending unit "tells" the computer anything besides the fuel level. I believe the fuel pump and sending unit (fuel level) are together in the tank. It has been replaced on our car, for what it's worth, and it didn't change anything. It still has a long start, and if you hold the accel pedal to the floor (and one foot on the brake, obviously) before you hit the button and through a start cycle, it will start and die. On second attempt with the accel pedal released, it starts perfectly. I still lean towards leaky injectors.

As far as the dealership experiencing the phenomenon, the misses works at the dealership. They are well aware of it.

I've had the same issue, and as I've said over a year ago, it was due to fuel pressure loss. I had a leaky injector which leaked fuel into the combustion chamber and thus flooding it. Leaving it for a long time would evaporate the fuel and thus no hard starts.

hansoac did you ever get your issue fixed? If so, what was the finding? Thanks

Nope. Mainly because it has been in storage. I have been driving it lately but it will ONLY start rough when it is very hot outside. The weather is in the 40s-50s so it starts fine regardless.

Just to follow up, our Z had 5 out of 6 injectors leaking fuel into the combustion chamber, just as I had suspected. All 6 were replaced, and the car starts beautifully.

Did your Z have the symptoms like mine? Only rough starting in hot weather??

No. Mine didn't like to start after it sat 1-4 hours. Hot and Cold weather didn't have an effect. Residual rail pressure caused the injectors to dribble.

Mine only has the issue in hot weather as well hansoac, and only after sitting for about 2 hours after being run. After all this time, I have finally brought my car to the dealership yesterday for this problem. I'll let you know what they find. Did you ever bring yours in to the dealer?

Well in case anyone still follows this thread or has this issue in the future; I am happy to say my issue has been resolved! Gearhead51 hit the nail on the head. I had an injector leaking. The dealer replaced all 6 injectors and the rough start issue I have had for nearly 25,000 miles has been eliminated. Good luck to anyone else who has the issue. Maybe your nightmare can be shortened thanks to the info in this thread. :)

Here is my youtube video again showing what the issue looks like:

http://www.youtube.com/watch?v=TGpdqrRNR2s

I would also like to add that initially the dealer did not find that the injectors were leaking however Nissan had them run further tests on them individually and this is when the leak was discovered.

Peace

The hard part is getting them to do the testing on the injectors. They repeatedly told me that those injectors don't leak. I was asking them to check them for months. Granted, testing them takes a good bit of time, but once they tested them (pulled them out, laid them on paper towels, and pressurized the system) the fix was obvious.

I'm not a tech anymore, but after years of wrenching, I still know what to look for. Good luck dealing with this. My girlfriend worked at the Nissan dealer, and had a heck of a time getting this resolved... to the tune of a year and 12,000 miles. We were worried the car would get out of warranty with this issue.

So I am reading some say its a crank position sensor, some a engine temp sensor, and some saying it's a leak in the fuel injectors.

My 1 year old Altima with 48K on it, randomly it will start but not until after cranking for 2-3 seconds. It's rare that it happens (2 times in almost 4 months) . It could be first thing in the morning or later after I have been driving. Thoughts on what I should try first?

The theorys of crank position sensor and engine temp sensors were just that. Theorys. The fix for this issue has been found and it is leaky fuel injectors. Have the dealership test each injector individually for leaks. Keep in mind however that this is only if you are experiencing the exact issue as we have. There could be many reasons for your car not starting properly, but the particulars of this issue have been documented in this thread by me, zero610, bclarke, gearhead (who ultimately provided the fix) and a few others.

Check out my youtube video that I posted earlier in this thread for an example of the problem so that you can see if yours is similar. Good luck!

Here is my video of the issue and a description:

http://www.youtube.com/watch?v=TGpdqrRNR2s

Thank you for the clear reply. I will be taking my car to the dealer soon as I am getting close to 50K. The problem is just like you showed, it wants to start however just cranks for a few seconds. I might even be able to get a example of this problem to show as well.

Does anyone know why the injectors will start to leak? Aggressive driving?

No explanation other than being faulty. I didn't drive my car hard, and my problem actually started around 10,000 miles. I didn't find the fix untill 30,000 miles!