My 2003 G35 6MT is now not starting. I know this a 350z forum, but it's pretty much the same car.

About a month ago or so I noticed that the car would randomly be slow to start up/weak start. It would slowly crank, start up, sounded very weak for a few seconds, and then go back to normal operations. I also notice that the car seem to accelerate slow and/or not as strong anymore, but that could be just something in my head.

So finally the other night I tried to start up my car, I just drove it a few hours ago, the car would start go through the initial process of trying to crank, then a click, and nothing. I took out the keys, tried it again, and it started up like a champ. The next morning the car started up fine and I drove it to work without an issue. Eight hours of sitting later I tried to start it up to go home and back to the same no starting issue. This time it would start twice (same issue as the previous night) and then on the third try it fired right up. When I got home I turned off the car, waited for a minute or so, tried starting it up and it did so I figured it was nothing. This morning it would not start at all. It just continued to go though the process of trying to crank, click, and nothing.

I've also noticed that during the past few months there has been a strong odor of gas/exhaust fumes when I start up the car after it has sat for a few hours. I can smell it right around the doors and front tires.

I searched around and found the possible fix: clutch ignition switch, starter, or fuel pump.

Hopefully with the details I provided someone can help me narrow it down to one of the fix. BTW I didn't mention the battery or alternator as being the issue because I just replaced it last year with an Optima red top and I believe there's plenty of juice left.

 

But did you load test the charging system?

Did you pull for any DTCs?

No one can guess at issues without pertinent information. And even with it, internet diagnosis is about as good as the paper it’s printed on. 😆

 

On initial belief, I would suspect electrical related. Either your battery/starter. In part because you mentioned the strong gas smell and weak acceleration which could be a result of the car running rich. Still, we would need more info.

Check engine light on?

 

Check starter grounds, if all is good, take your started to get tested. Probably just a bad starter.

 

It is probably your starter. The starter itself might be failing, but I my guess is that the wiring to the starter is the problem. To fix this, I would physically remove the starter and check it carefully. If the starter appears to be in good condition (and it probably is), reinstall it and do all the connections. I'll bet this solves the problem.