My 2003 G35 is now not starting. 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 searched around and found some possible fixes: clutch ignition switch, starter, fuel pump, spark plugs.

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 the battery last year with an Optima red top and I believe there's plenty of juice left.

 

Don't assume it's not the battery, have it load bank tested, clean the posts and lugs. OBD2 scan for hidden codes. If all that checks out it's probably the starter since it's starting sluggishly when it does crank.

 

Just because you purchased a battery a year ago doesn't mean it doesn't have a weak cell?
When the vehicle was running did you measure 14.4v across the battery coming from your alternator?
If you don't have a digital multi meter get one
Also obtain a battery hydrometer to test the individual battery cells
More than likely you have a defective battery?

 

It's a sealed Optima battery, won't be able to hydrometer the thing but you can load bank it.