4.8 wont start!! PLEASE HELP.
02-21-2012, 08:01 PM
#11
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ok i have some good news kinda.. i checked the fuel rail and injectors and they seem to be firing fine.. the pressure seems to be good to but ill get it checked for sure.. I had my dad spray reg 87 octane fuel into the intake and it started right up and kept going until he stop spraying. now my Q is did i dilute the gas so much with that stp fuel injector cleaner that it cant ignite in the chamber?? i told my should i should just put new gas into it and see if that works, he said its not the gas but i think it is.. tell me what you guys think?
02-21-2012, 08:45 PM
#13
Moved to Engine section.
As far as the engine firing, it's either air, fuel, or spark. If it's starting when spraying into the intake manifold that removes the air and spark variables, so it has to be fuel. If you have good rail pressure, it's either bad gas or the injectors aren't firing. If you crank it over for a few seconds and pull a plug, is the plug wet or dry? That should answer the question about the injectors firing.
Not sure about the coolant in the oil thing. Are you sure it's actually coolant and not condensation?
What part of Phoenix are you in?
As far as the engine firing, it's either air, fuel, or spark. If it's starting when spraying into the intake manifold that removes the air and spark variables, so it has to be fuel. If you have good rail pressure, it's either bad gas or the injectors aren't firing. If you crank it over for a few seconds and pull a plug, is the plug wet or dry? That should answer the question about the injectors firing.
Not sure about the coolant in the oil thing. Are you sure it's actually coolant and not condensation?
What part of Phoenix are you in?
02-21-2012, 08:47 PM
#14
Here you go for the heads and what to look for!!! There is a thread link withen for the GM TSB on this very issue.
https://www.performancetrucks.net/fo...-crack-473251/
https://www.performancetrucks.net/fo...-crack-473251/
02-21-2012, 09:01 PM
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Moved to Engine section.
As far as the engine firing, it's either air, fuel, or spark. If it's starting when spraying into the intake manifold that removes the air and spark variables, so it has to be fuel. If you have good rail pressure, it's either bad gas or the injectors aren't firing. If you crank it over for a few seconds and pull a plug, is the plug wet or dry? That should answer the question about the injectors firing.
Not sure about the coolant in the oil thing. Are you sure it's actually coolant and not condensation?
What part of Phoenix are you in?
As far as the engine firing, it's either air, fuel, or spark. If it's starting when spraying into the intake manifold that removes the air and spark variables, so it has to be fuel. If you have good rail pressure, it's either bad gas or the injectors aren't firing. If you crank it over for a few seconds and pull a plug, is the plug wet or dry? That should answer the question about the injectors firing.
Not sure about the coolant in the oil thing. Are you sure it's actually coolant and not condensation?
What part of Phoenix are you in?
or maybe its from a cracked head
. i will try looking at the spark plugs. but im pretty sure they are getting fuel. it has to be from the gas!! like i said i was almost on Empty when i put that stuff in thinking it would do extra cleaning. that was dumb of me, i know.. im live up north on 65th and catus
02-21-2012, 09:16 PM
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You've kinda answered your own qustions.
1: it starts and runs if you put fuel into the intake, so its fuel related.
Go get a fuel pressure gauge and let us know what it is. put fresh fuel in 1st
2: add a couple gallons of fresh gas, not too much, my hunch is your fuel pump and or filter is toast.
what year is the truck? is it a return style fuel system? i.e. there will be two lines that go to the rails. return-less there is one.
3: was there water in the oil before you changed the heads? you didnt change the oil after you did the heads, there is a good chance thats where your water came from. change the oil!!!!!
hope this is a better start
Edit i saw this is an 05 so your fuel filter is in the pump....... yep have fun i recomend lifting the bed.... much eaiser.
1: it starts and runs if you put fuel into the intake, so its fuel related.
Go get a fuel pressure gauge and let us know what it is. put fresh fuel in 1st
2: add a couple gallons of fresh gas, not too much, my hunch is your fuel pump and or filter is toast.
what year is the truck? is it a return style fuel system? i.e. there will be two lines that go to the rails. return-less there is one.
3: was there water in the oil before you changed the heads? you didnt change the oil after you did the heads, there is a good chance thats where your water came from. change the oil!!!!!
hope this is a better start
Edit i saw this is an 05 so your fuel filter is in the pump....... yep have fun i recomend lifting the bed.... much eaiser.
Last edited by 1dirtybird; 02-21-2012 at 09:26 PM.
02-22-2012, 09:44 AM
#18
Yeah so given what you have said I would add some fresh fuel and see if it starts. Also, when you put the heads back on did you use new head bolts? The stock ones are torque-to-yield, which means that they stretch when torqued to spec, and are not meant to be reused.
You're not too far away, I am just off of 7th Ave and the 101. Good to see another AZ guy on the boards
You're not too far away, I am just off of 7th Ave and the 101. Good to see another AZ guy on the boards
02-22-2012, 06:02 PM
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im going to drain the gas out but i cant seem to find the fuel pump relay or fuse to do it. its a 05 silverado 4.8. i know its labbled on the back of the fuse box but i cant be sure witch one it is??