Starting and iddling problem with our 68
10-21-2012, 03:41 PM
#1
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Starting and iddling problem with our 68
We are trying to get our 68 Road Runner back on the road after a long sleep. After cleaning the gas tank and carburator, we seem to have 2 problems. The car will not idle (runs at 1300 RPMs) and most of the time after the car has been running at temperature, trying to re-start it, the car turns over and wants to start after the key is being turned off. It does this when it is cold. We have replaced the ignition switch, balast resister, voltage regulator, ECU, coil. We have checked the distributor and cleaned all of the wiring connectors. Everything seems to be at specs. Any suggestions?
10-22-2012, 10:39 AM
#3
WHERE IS the timing set?
I am assuming that what you are referring to as "wants to start" does NOT mean that the starter motor is cranking, which would be an electrical problem, but rather what many call "dieseling" or "after run"
This is probably related to the high idle, and may be made worst by retarded timing, carbon in the cylinders, etc.
What do you mean by "won't idle" below 1300?
Do you mean if you turn down the idle speed screw that it dies?
Or do you mean you can turn the speed screw clear down and it simply won't idle down?
Check the throttle cable clamp and the action of the accelerater pedal that it is not "hanging up" and is allowing the carb to return to slow idle.
Check the automatic choke linkage. Maybe it is assembled incorrectly, is binding up the throttle. Is the choke opening all the way?
Vacuum leaks -- very possible, wrong, damaged base gasket, etc. How did you tighten the carb down? Always be VERY "light handed" tightening down a carb -- go criss--cross and use your hand up on the ratchet head as you would a screwdriver, I go across the carb bolts probably as many as 5-6 times before I call it "snug" and all 4 are even.
To check for leaks, use a scrap piece of fuel hose held at your ear, and go around the bottom of the carb and hose(s) connections. You can also use a small pump sprayer with simply water. "Spritzing" a little water at a leak will cause a change in idle.
How did you set the idle, the speed, the mixture?
I am assuming that what you are referring to as "wants to start" does NOT mean that the starter motor is cranking, which would be an electrical problem, but rather what many call "dieseling" or "after run"
This is probably related to the high idle, and may be made worst by retarded timing, carbon in the cylinders, etc.
What do you mean by "won't idle" below 1300?
Do you mean if you turn down the idle speed screw that it dies?
Or do you mean you can turn the speed screw clear down and it simply won't idle down?
Check the throttle cable clamp and the action of the accelerater pedal that it is not "hanging up" and is allowing the carb to return to slow idle.
Check the automatic choke linkage. Maybe it is assembled incorrectly, is binding up the throttle. Is the choke opening all the way?
Vacuum leaks -- very possible, wrong, damaged base gasket, etc. How did you tighten the carb down? Always be VERY "light handed" tightening down a carb -- go criss--cross and use your hand up on the ratchet head as you would a screwdriver, I go across the carb bolts probably as many as 5-6 times before I call it "snug" and all 4 are even.
To check for leaks, use a scrap piece of fuel hose held at your ear, and go around the bottom of the carb and hose(s) connections. You can also use a small pump sprayer with simply water. "Spritzing" a little water at a leak will cause a change in idle.
How did you set the idle, the speed, the mixture?
10-22-2012, 11:09 PM
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Thank you!
We really appreciate your responses and help to figure out our problems. It is an AVS carburetor.
When it is cold and we try to crank it over, when you turn the key off, it tries to start. After it has been running and shut off and you try to start it again, it doesn' try to turn over until you turn the key off.
When it starts, it fast idles fine. After it has warmed up to 180 degrees, rather than idleing down, it dies before I can turn the idle screws.
The choke is fuly open, but it won't run.
I have checked the cable clamp and the accelerator pedal and they are fine.
The choke is opening all of the way.
I have checked for vacuum leaks and tightened the carb the way you suggest.
I canniot get it to idle long enough to adjust the idle mixture screws. They are about 2 1/2 turns out.
I just finished rebuilding the carb. I have taken it out and checked it 4 times. The base gasket is new.
It had bad gas and rust, but I have taken it all apart and cleaned it.
I was suspiscious of vacuum leaks, but cannot find any. I have clamped hoses and plugged the carb, but noting has changed anything or made it better.
I have checked all of the electrical parts by the book. Even the distributor. I marked it before i took it out. Timing could be a possibility.
Any other sugestions?
When it is cold and we try to crank it over, when you turn the key off, it tries to start. After it has been running and shut off and you try to start it again, it doesn' try to turn over until you turn the key off.
When it starts, it fast idles fine. After it has warmed up to 180 degrees, rather than idleing down, it dies before I can turn the idle screws.
The choke is fuly open, but it won't run.
I have checked the cable clamp and the accelerator pedal and they are fine.
The choke is opening all of the way.
I have checked for vacuum leaks and tightened the carb the way you suggest.
I canniot get it to idle long enough to adjust the idle mixture screws. They are about 2 1/2 turns out.
I just finished rebuilding the carb. I have taken it out and checked it 4 times. The base gasket is new.
It had bad gas and rust, but I have taken it all apart and cleaned it.
I was suspiscious of vacuum leaks, but cannot find any. I have clamped hoses and plugged the carb, but noting has changed anything or made it better.
I have checked all of the electrical parts by the book. Even the distributor. I marked it before i took it out. Timing could be a possibility.
Any other sugestions?
10-23-2012, 11:37 AM
#7
What you describe for starting is "starting" to sound like an ignition switch that has broken up internally. Switches are not that expensive, and if your key/ lock is in OK shape, you can put old key lock cylinder into the new switch
The carb sounds to me like if you are sure about vacuum leaks, you must be getting crap into the carb (rust, dirt) from the tank, I'd pull the top of the carb off WITHOUT draining the fuel and inspect.
(On an AFB, I can do that right on the car. Be careful of the clips!!)
The carb sounds to me like if you are sure about vacuum leaks, you must be getting crap into the carb (rust, dirt) from the tank, I'd pull the top of the carb off WITHOUT draining the fuel and inspect.
(On an AFB, I can do that right on the car. Be careful of the clips!!)
10-23-2012, 12:19 PM
#8
Mopar Lover
how long ago was the last time it was running before the rebuild wk month yr
sounds like its running lean
i know since they have been adding alcohol to the mix i have had to richen up all my carbs holly, thermo, carters,
i dont even run holly any more the carbs in my experience cant handle the fuel
lets say your motor has been setting for a few years, and the market fuel has degraded so much since then now what your carb was jetted for "gasoline" is now lean
sounds like its running lean
i know since they have been adding alcohol to the mix i have had to richen up all my carbs holly, thermo, carters,
i dont even run holly any more the carbs in my experience cant handle the fuel
lets say your motor has been setting for a few years, and the market fuel has degraded so much since then now what your carb was jetted for "gasoline" is now lean
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