Hard starting when hot

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Easy way to test the purge valve. Start the engine, unplug the electrical connector and remove the emissions line from the purge valve that goes back to the charcoal canister. Put your finger over it and see if you feel a vacuum. If there is, the purge valve is bad.
 
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You may have to continue driving the vehicle. It needs to see a wide range of driving patterns. Some GM cars require turning on the rear defroster on a engine cold start for instance. I’m not sure about Nissan though, maybe someone else can chime in about that.
 

LeakySeals

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Easy way to test the purge valve. Start the engine, unplug the electrical connector and remove the emissions line from the purge valve that goes back to the charcoal canister. Put your finger over it and see if you feel a vacuum. If there is, the purge valve is bad.
Just confirming. I'm testing vacuum before or after the purge valve? Am I testing the solenoid to be shut or open?
 

LeakySeals

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Finally after a week I get this
 

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LeakySeals

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Seems like a lot of the problems I'm fixing on this 06 Altima are the same problems the 03 Maxima had. I took the vent valve off. Blew it out. Sprayed it out with some electrical contact cleaner. Put it back. My code reader can test the EVAP so I sent a test and I could hear the solenoid click. So maybe it was stuck. Or maybe it's the purge valve up front. I did not hear that click during the EVAP testing. I'm assuming it's s similar solenoid.

So.. the long crank hard to start when warm problem continues. At this point I should probably start looking at fuel pressure as the cause. Maybe a faulty check valve or regulator. I don't see a obvious spot to check fuel pressure.
 

LeakySeals

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Some live data. Note the ltft stuck on 0. It's been like that since I started driving the car last week. I wonder if it's related to evap being not ready. 20201019_165648.jpg 20201019_165801.jpg 20201019_165619.jpg
 

LeakySeals

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Check this out. Live data with the engine turned off for a few minutes. Maybe the stock intake snorkel is disconnected somewhere. Look at the IAT. Ambient temp is 62f

20201019_174106.jpg
 

LeakySeals

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Have you tried cycling the key on and off several times before trying to start? Key on until you hear the fuel pump shut off, then key off, repeating a few times?
That's what I was thinking. Weak/low/no fuel pressure.
I tried that. It always starts. Not sure if I was doing that at the right time. Like when it's hard to start. So I waited until there was an extended crank. Turn the key off. Try to start again boom starts right up. I can hear what sounds like the pump priming every time as I turn the key. Or is it the throttle body plates adjusting which is something these cars do. I'm going to pull out the back seat and test again see if I can hear it.
 
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I tried that. It always starts. Not sure if I was doing that at the right time. Like when it's hard to start. So I waited until there was an extended crank. Turn the key off. Try to start again boom starts right up. I can hear what sounds like the pump priming every time as I turn the key. Or is it the throttle body plates adjusting which is something these cars do. I'm going to pull out the back seat and test again see if I can hear it.
You are hearing the fuel pump. Sounds like the fuel system is losing prime.
 

LeakySeals

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Sorry if these are dumb questions. If.. Prime is not a problem when the engine is cold or it's been sitting overnight. Prime is a problem when the engine is warm and it's been sitting for 30 minutes. Is that because there is less prime when it's warm? Is there a check valve somewhere that has failed? Pressure sensor fail? Is prime reliant on the engine coolant temperature sensor? Ambient temperature sensor?
 
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Use a scanner to view live data and let us know if the engine coolant temperature is giving good data or not.
This would have been the first thing I would have done instead of throwing parts at it.
 
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Sorry if these are dumb questions. If.. Prime is not a problem when the engine is cold or it's been sitting overnight. Prime is a problem when the engine is warm and it's been sitting for 30 minutes. Is that because there is less prime when it's warm? Is there a check valve somewhere that has failed? Pressure sensor fail? Is prime reliant on the engine coolant temperature sensor? Ambient temperature sensor?
Usually fuel pumps lose prime while sitting overnight or at least an extended amount of time. This sounds more like an issue with a sensor, possibly a temp sensor.
 
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Usually, fuel pumps lose prime while sitting overnight or at least an extended amount of time. This sounds more like an issue with a sensor, possibly a temp sensor.


He could be dealing with a flakey fuel pump though. Just like a starter, they sometimes don't work properly when hot. Although you'd think the fuel pump would cool down fairly quickly since it's submerged in fuel.

Just food for thought might be worth checking fuel pressure when cold and when you're experiencing the extended crank.
 
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