Nissan Repair: 2000 nissan frontier, fuel pressure regulator, nissan cars

Question
have customers 00 frontier.when it gets at or below 32deg,truck will crank,but not start.have spark,fuel,compression.bring it in garage for a little while,starts right up.when outside and cranking,smell unburnt fuel,plugs wet with it.checked computer parameters,ect reading proper.air temp ok,maf seems ok also.unplug ect,reads 104deg,still no start.fresh tuneup,etc.already done.only code in memorypo325-knock sensor prob.cant see this as a starting prob.putting spark tester on plug wire,jumps gap,but not thrilled with size of spark.seems to want to flood plugs out when cold,but really see no reason for it.this on has me stumped.please e mail me with any isight you may have.local dealer is no help.thank you.

Answer
If the crank angel sensor is bad it could allow the injectors to flood the engine.  Also, the fuel pressure regulator is a problem with these and at that cold a temperature it might not be releasing allowing excessive pressure to surge the injectors allowing the flooding.  I had a 350Z with this problem and it turned out to be the fuel pressure regulaotr.  On the Z the regulator is part of the fuel pump assembly so it was a complete replacement.  Also, found that if you put gas treatment in the tank the regulator will go bad on Nissan cars and trucks since the fuel system only uses one line to the intake and no return line.  The bleed off regulator is in the tank and when caustic substances are introducted they do not have time to dissipate into solution like on cars where the regulator is on the fuel rail.  Also, check the fuel pressure to diagnose the problem.  There is no pressure port since Nissan deleted it.  You will need to fabricate your own or get the one from KD tools, Snap-on or MAC. I seem to remember something like 41 psi at an idle for the pressure.  If yours is over by 10 percent or more the regulator is bad.  Lastly, I had another Nissan Maxima where the injectors were really dirty and I ended up using the fuel cleaner kit.  The car really responded to the cleaning.  This is the one from NAPA or the tool guys that uses the can of cleaner.  But, again you have to get the adapter kit since there is no port to screw onto on the Nissan products.