5.7 Vortec issues

[Sam A]

I have a 1998 k1500 that I just replaced the engine in, and it does not seem to be running right at idle. The engine has new updated spider injection, plugs,wires, distributor, rotor and cap. 

 

After it warms up the motor will idle funny and if I turn the truck off and let it sit for a few minutes it is hard to crank ( spits and sputters and sometimes cuts off) I have to pay the gas to get it to run. It also has hesitation when taking off from a stop. Running down the rd the truck runs great. 

 

The truck has long tube headers and true dual with no cats. 

 

The only codes are a random misfire and knock sensor. 

 

I have pulled the plastic cover off the intake to look for fuel leaks and have found gas pooled up in the intake and air ports that go to each cylinder, I hooked the fuel lines back up to the spider with the cover off and cycled the key making the pump run but did not see any leaks and fuel pressure holds good for a few minutes. 

 

I have been going around and around chasing this problem and still no solution. 

 

What else could be causing the motor he motor to run rich like this? 

 

Any help is much appreciated 

[diyer2]

Does it have this part?

My guess  IAC - Idle Air Control is bad.

From your description everything else is good.

 

[Sam A]

I’ve replaced the idle control and the throttle position sensor and no change, I’ve even taken one off a good running truck and it didn’t help 

[riverbanks]

So the pooling was in every intake runner with intake valve closed?it's bleeding down somewhere,who's spider?

[Sam A]

Ac delco spider and I’ve tried 2 of them

[riverbanks]

Keep your thread going, someone will respond,I'm drawing a blank

[TW97C1500]

Leaking fuel pressure regulator maybe.  It is inside the upper manifold.

[riverbanks]

Makes sense, vacuum with intake intact, enough to help pull it out?

[Sam A]

I don’t think it’s the fuel regulator because I’ve had the upper intake off with the fuel lines connected and cycled the fuel pump a few times to see if I could see it leaking and as far as I can tell it is not, also the fuel pressure holds pretty good around 50 with the key off, I would think if there was a leak it would drop pretty quickly 

 

 

[Sam A]

I’m going to do a vacuum test tomorrow to see if that can tell me anything, also does anyone know what the proper reading should be for the map sensor? 

[riverbanks]

Try www.axleaddict.com/symptoms of a bad map sensor,great write up

[rjm1998]

Did you ever figure out your problem?