2004 Nissan Sentra Hard to start when hot weather

2004 NISSAN SENTRA
77,000 MILES • 4 CYL • FWD • AUTOMATIC
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FHER79RM
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Hi, i already posted the problem but the symptoms the car was giving weren't clear to me until now.

Here how it goes:

I live in a very hot area (110° F average in summer).

I get to work at 5:45 am and at that time the car starts allright.

At work my car is in a shaded parking lot, at 9:00 am i go out to have breakfast and the car starts fine.

Later when i finish working, I go to eat and I leave my car parked on the street (with the sun heating up car) if it is for a short period of time, more or less half an hour, the car starts ok, but if it's stays longer, I have to turn the switch on for three times to make it start.

The idle speed is doing good now, i finally did the idle speed air learning procedure and the car doesn't stall on P or N position but still have that starting problem.

Would you help me please?
Jul 22, 2009 at 9:32 AM
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KHLOW2008
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Hi fher79rm,

Turning the ignition on/off a few times before vehicle can start seems to indicate a problem with the fuel pressure or vapor lock.

It could be a faulty fuel pressure regulator which is together with the fuel pump in the fuel tank.

It would be advisable to do a pressure test to confirm if it is the fuel pump or regulator.
Jul 22, 2009 at 10:10 AM
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FHER79RM
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I'll have the pressure checked on friday and I'll let you know, thanks! :)
Jul 22, 2009 at 12:00 PM
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KHLOW2008
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The pressure might be ok within a short period so you might need to hold the test over extended period to know if the regulator is slowly leaking.
Jul 22, 2009 at 12:43 PM
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FHER79RM
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But, even when the car starts ok in the morning after being all night parked, do you think is the regulator?

Or maybe because is cooler the car doesn't need that much pressure because fuel is not vaporized and when it gets hot, needs more pressure to pump the fuel vapor?.

How do you think is appropiate to make the test?, can you give some basic steps (considering i can get the fuel pressure meter)
Jul 22, 2009 at 2:15 PM
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KHLOW2008
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You are correct, if cold starting is good, it most probably is not the fuel pressure regulator.

Vapor lock and lean fuel trims would be more likely to cause it. Would you be able to get the freeze frame data for the Engine Coolant Temperature sensor? A scanner would be required to do the test.
Jul 22, 2009 at 2:34 PM
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FHER79RM
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Hi,well i cannot get a scanner, I guess the only thing I can do is to get the car to Nissan workshop. Before doing it I still will do the fuel pressure test tomorrow and see how it goes and I'll let you know to see if we go to the next step.

If the pump was the problem, would I have to buy the whole pump? or there is some kind of repair kit for it?, because is almost $400. That's a lot of money! :s
Jul 23, 2009 at 9:27 AM
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KHLOW2008
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The pump unit is universal for most models and can be replaced separately but dealer parts would be as an assy.

Maybe you can try enquiring at your local parts store for a generic replacement pump only.
Jul 23, 2009 at 9:36 AM