1981 will not accelerate when engine cold.
Thread Starter
Heel & Toe
Joined: Aug 2012
Posts: 22
Likes: 0
From: Arizona
1981 will not accelerate when engine cold.
My 1981 corvette will not accelerate when engine is cold. Have to gently pump accelerator to get it to go. Little to no response from pedal other than extreme hesitation and near stall. Runs great when warmed up.
Here's what I have done.
Rebuilt the Quadrajet
Replaced computer
Put new plugs wires rotor and cap on.
Replace intake manifold gasket.
Cleaned EGR valve.
Set timing to 6* BTDC
Dwell on 6 cylinder scale reads 28* and goes up to 35* with rpm increase.
Idle air bleed set to 5/32 "
New TPS
New MCS
Electric Choke sets with engine cold at 1/8" open and opens as choke heats up in about 2 minutes.
This is very annoying. Tired of sitting for 10 minutes waiting for engine to reach operating temp to drive.
Anyone have any more ideas?
Here's what I have done.
Rebuilt the Quadrajet
Replaced computer
Put new plugs wires rotor and cap on.
Replace intake manifold gasket.
Cleaned EGR valve.
Set timing to 6* BTDC
Dwell on 6 cylinder scale reads 28* and goes up to 35* with rpm increase.
Idle air bleed set to 5/32 "
New TPS
New MCS
Electric Choke sets with engine cold at 1/8" open and opens as choke heats up in about 2 minutes.
This is very annoying. Tired of sitting for 10 minutes waiting for engine to reach operating temp to drive.
Anyone have any more ideas?
Melting Slicks
Joined: Jul 2010
Posts: 2,503
Likes: 33
From: McGrady NC
St. Jude Donor '15-'16
Is the accelerator pump lever in he correct hole? Does it act lean at all after it warms up? Thinking about a cold-state vacuum leak somewhere. Is the rest of your vacuum system in good shape? Does it crank OK when the engine is warm? Thinking about a slipped balancer ring throwing the timing off a little. Float setting a little low? Choke pull-off working too quickly? Just taking stabs at a lot of possibilities...
Thread Starter
Heel & Toe
Joined: Aug 2012
Posts: 22
Likes: 0
From: Arizona
New coolant temp sensor, replaced headlight vacuum check valve and headlight actuator seals. Tested vacuum system with tester. All is good. Cranks fine hot or cold.
I'm thinking choke pull off working to quickly as well, creating a lean carb at cold operation because stepping on pedal I can feel response from accelerator pump action but no acceleration from fuel flow .
Once engine reaches operating temp it runs great.
I'm thinking choke pull off working to quickly as well, creating a lean carb at cold operation because stepping on pedal I can feel response from accelerator pump action but no acceleration from fuel flow .
Once engine reaches operating temp it runs great.
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
New coolant temp sensor, replaced headlight vacuum check valve and headlight actuator seals. Tested vacuum system with tester. All is good. Cranks fine hot or cold.
I'm thinking choke pull off working to quickly as well, creating a lean carb at cold operation because stepping on pedal I can feel response from accelerator pump action but no acceleration from fuel flow .
Once engine reaches operating temp it runs great.
I'm thinking choke pull off working to quickly as well, creating a lean carb at cold operation because stepping on pedal I can feel response from accelerator pump action but no acceleration from fuel flow .
Once engine reaches operating temp it runs great.
could your thermostat be stuck open?
the temp sensor sends an ok at 150deg. 02 is warm by then.
I hear a definate rich to lean motor sound when those 2 sensors get to temp.
under 3 mins.
I have driven with bad 02 and coolant sensor, IE full rich and never had the issues you describe. but I don't beat on it.
not saying you are.
curious what sol number of turns you use and what
idle mix turns and air bleed turns.
Thread Starter
Heel & Toe
Joined: Aug 2012
Posts: 22
Likes: 0
From: Arizona
Problem solved. It was the M/C solenoid adjustment. Thought I had set it when I rebuilt the carb but did not. Adjustment was all the way in. Carb wasn't seeing full rich because metering rods were not raising up enough to allow rich fuel mix at cold operation.
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