79 trans am will start and cold idle but wont idle when warm

[king79transam]

I have a 79 trans am I have working on that I just replaced the fuel pump and replaced many vacuum hoses. It will crank fine for the most part and hold an idle, however after it warms up it will still crank but will not idle. Any thoughts of what could be the cause?

 

[melsg5]

Need more background on the general maintenance, plugs, cap and rotor, plug wires, timing check, etc.
Did you adjust the idle speed screw or idle solenoid and if accessible the idle mixture screws?

 

[cammerjeff]

Also what Carb? Is the choke opening?

 

[king79transam]

Plugs and wires are good, timing is good
Havent checked cap and rotor but yes did adjust idle speed screw.
It is a 4 barrel Rochester and yes choke is opening

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[melsg5]

What about the idle mixture screws, can you/did you adjust them?

 

[king79transam]

Have not touched the idle mixture screws, this car has been sitting for about 20 years in a shed so trying to find what all has gone bad

 

[melsg5]

That's a different story. The carburetor may be gummed up or the inlet filter clogged. Check the filter first but be careful you dont strip the inlet threads. You also should try adjusting the mixture screws.

 

[tico4life]

I have a 79 trans am I have working on that I just replaced the fuel pump and replaced many vacuum hoses. It will crank fine for the most part and hold an idle, however after it warms up it will still crank but will not idle. Any thoughts of what could be the cause?

Did you figure out what was wrong, I have the opposite problem, rough idle when cold but perfect when warm!

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[melsg5]

Did you figure out what was wrong, I have the opposite problem, rough idle when cold but perfect when warm!

Check your other post

1979 Trans Am rough idle when cold

I have a 79 trans am with a 400 6.6 Msd distributor Eldelbrock performance intake 750 Eldelbrock carburetor not an RV Cam but the nex size up is what the older owner told me who building engine. It idle perfectly when it worms up but first stars for like a minute or so idle really rough.

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