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I've had a problem with my 2004 Civic not starting occasionally (mostly between 5-10 min. / 1hr 30min.) after turning the engine off. I've spoken to 2 different mechanics, one said it was a problem with the crankshaft position sensor. The other one said that it was likely a problem somewhere within the fuel system because, 1. There are no codes, and 2. he sprayed starting fluid into the air intake which allowed the car to start, and he said that means it should be a fuel problem, and not an electrical problem.
The fuel pump was replaced a little under a year ago.
If anyone has any ideas as to what the specific problem could be, I would be very appreciative.

 
Rep Power: 222

Sounds like fuel is the right place to start.
If you can't troubleshoot, you're going to have to pay someone to do it.