I have a 1998 Acura TL 3.2 L V6 4-speed automatic with 241,000 miles that turns over but does not start intermittently. Randomly about once a month it leaves me stranded in summer or winter. I have already had the battery, starter and main relay replaced. Scan tool at independent mechanic shop (not dealer) does not show any codes. Once I got it to start after wiggling the shifter between the gears and back into park. Another time I got it to start after giving it a hip nudge from the back while in park. This last time I left it at my mechanic for two weeks and he could not replicate the issue, it started for him everyday without fail. What could be causing this mysterious problem?
Your mechanic's nose is getting longer. There has to be a lock out in connection with the transmission selector that's causing this. The neutral safety switch ( Advance Auto # J40501303320EA - $86.25) may also be causing your problem.
If it is not the lockout like @doc said, it may be the fuel pump assembly. This is just a guess based on my Honda Accord 1999, which may share some common design features as the TL.
The two different culprits when my Accord had trouble starting, the relay under the steering wheel, and the fuel pump assembly.
