Changed heads and now truck is dead

[bobbennett]

I have a 99 Yukon with a 5.7. I screwed up and blew a head gasket the other day. I changed both heads, head gaskets, intake gaskets, valve seals and everything else that comes in the kit. Now that I have everything back together, I turn the key and it wont turn over. If I cross over the selenoid the truck starts but runs at full throttle around 5500 RPMs. I have checked all of the ground wires and they are on and all of the plugs are plugged back in. The truck ran before tear down it just blew exhaust into the coolant and now nothing. Any help is greatly appreciated.

 

[retorq]

Ddi you pinch a wire between the head and block perhaps?? Intake and head??

 

[bobbennett]

Double checked all of that multiple times. Wiggled all the harnesses, pulled all the wires and checked every ground that I could find.

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[SunlitComet]

Is you throttle stuck open or something? Or some huge vacuum leak around your throttle body or around the fuel body where it goes thru the plenum?

 

[bobbennett]

No the throttle is fine, the butterfly is closed and I have all the vacuum lines attached. The valve covers are off as I still have to adjust the valves

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[SunlitComet]

Then if the map sensor and brake booster lines are properly fitted to the intake with no leaks around the plenum and the fuel body o-ring is in place, I suspect your IAC is stuck open. Trying turning key on and off and on and off for twenty second between each key movement to get the pcm to set it correctly. if still no go remove it and see if the pintle moving properly when you turn key on. Retract it before putting it back in if it extended out real far.

 

[bobbennett]

Ok will try that in the morning thanks

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[bobbennett]

Ok truck is back running. What I did was change out every ground point in the engine compartment and then I reset the pcm as you described. Worked like a charm. Thanks for the assistance.

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[SunlitComet]

likely the ones on the thermo housing that were the problem then.

 

[bobbennett]

Yeah they didnt look bad but after I changed them all it started with no problem. Thanks again

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