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08 silverado trouble starting


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Bigbear1986
New User

Apr 6, 2017, 8:38 AM

Post #1 of 7 (330 views)
08 silverado trouble starting Sign In

My 08 silverado 1500 ltz wont start right away after filling with gas. I have to hit the gas pedal usually to get it to turn over. I do have codes p0171, p0174 and p0446. I have replaced the fuel pressure regulator and the fuel control valve. Any help would be appreciated


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 6, 2017, 1:48 PM

Post #2 of 7 (299 views)
Re: 08 silverado trouble starting Sign In

You have extreme lean mixture for some reason. You need to look for any vacuum leaks or air leaks in the intake snorkel.
You may have to smoke test the system to find it.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



kev2
Veteran
kev2 profile image

Apr 6, 2017, 2:52 PM

Post #3 of 7 (287 views)
Re: 08 silverado trouble starting Sign In

 P0171 and p0174 running lean - vacuum leak, fuel pressure, restricted injectors, clean MAF - do NOT use a oiled (K&N) type filter.
P0446 Evaporative Emmission Control System Vent - Does pump kick off often when refueling? check for 12v at vent solenoid, ther is a common issue with this code see TSB 02-06-04-037I -


Bigbear1986
New User

Apr 9, 2017, 3:29 PM

Post #4 of 7 (245 views)
Re: 08 silverado trouble starting Sign In

I did the fuel pressure test and when i turn the key on it goes to 60 then slowly starts to drop. Once i start the truck it stays steady at 43. Once i shut it off it starts to drop slowly but consistently. Would you have any ideas as what it might be


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 9, 2017, 3:41 PM

Post #5 of 7 (243 views)
Re: 08 silverado trouble starting Sign In

Are you sure about that running pressure? That is too low.

What engine does this have?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Bigbear1986
New User

Apr 9, 2017, 4:58 PM

Post #6 of 7 (233 views)
Re: 08 silverado trouble starting Sign In

It has the 5.3l v8 the paperwork i have says that is normal running pressure but why would the pressure be dropping so quickly


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 9, 2017, 5:03 PM

Post #7 of 7 (229 views)
Re: 08 silverado trouble starting Sign In

 The spec is Fuel Pressure (Key ON, Engine OFF) 345-414 kPa (50-60 psi)
It shouldn't be dropping that much when running.

It could be leaking back into the tank due to a bad check valve in the pump, a leaking injector or bad regulator.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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