99 suburban longer starting in the morning

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pollac17

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ok I have a suburban that starts up in 1 second all the time EXCEPT in the morning after sitting all night it takes 3 seconds. What could cause this?

Fuel pressure is excellent and holds strong (brand new fuel pump (delphi) and fuel filter (AC delco). 60 psi.

Air filter new

Coolant temperature sensor new (the one near the thermostat for the ECM)

In the morning when I know it will be a 3 second start I will cycle the key back and forth a few times to run the fuel pump over and over (fuel pressure raging at 60psi++) And still, 3 second start. If I don't cycle the key first to prime, still 3 second start.

The rest of the day, even after sitting for 5 hours, it will 1 second start.

Isn't that perplexing??

Truck runs great once its started and absolutely mint once its warmed up.

No check engine light

I will say though I think I am getting below normal fuel economy. Maybe 10-12 mpg city.

Does anyone have a theory? Thanks I look forward to discussing this matter with other suburban enthusiasts.
 
How long does the fuel pressure hold after turning off the engine?
Do you have a check engine light on?
Have you removed the vacuum line going to the fuel pressure regulator and checked for gasoline?
 
I haven't checked the fuel pressure regulator but the fuel pressure is strong and holds.

Do you really think it could be the fuel pressure regulator when the condition occurs even when I prime the fuel system over and over and fuel pressure is built up?

The only factor that causes the 3 second start is 8 or more hours of sitting. Shouldn't I be able to get fuel into the fuel pressure regulator and build up pressure at the injectors with the engine off by running the fuel pump? This is why I don't think its a fuel issue.
 
if it holds for multiple minutes than not the FPR, otherwise it is an easy thing to check, also consider the EGR valve and passage having carbon build up.
 
I had a similar problem on my 2002. First start of the day it wouldn't start right away.
I would turn the key to the run position and let the voltage rise before turning it over it would start right away. I need to get my battery tested.

I also cleaned the mass air flow sensor and it seems to be starting ok so far.

I'm not really a car guy though, so YMMV.
 
explain how the egr valve can cause this condition. Thanks
 
also i don't think the MAF sensor can cause this is the mixture on startup is predetermined based on the coolant temperature sensor. Am I wrong? can't see the MAF causing this.
 
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