Engine idle not working

[Fordication]

Hey guys. Just brought a 73 Challenger home from Wisconsin to Texas. I actually drove it home. Along the way I changed the oil and balanced the tires and rotated. I repaired a few broken hoses that are vacuum related. Got home on Monday night and the car made it home. Although the idle was low it still made it. So Tuesday I woke up and tried to start the car and it turns over and fires up then dies. Me thinking I fixed too may vacuum leaks I primed the carb with a bit of gas and it leaks out the bottom of the carb. So I think time for a rebuild. So I bought the kit and rebuilt the carb. So today I put the carb back in and the car still does not want to run. So I cranked up the idle screw to max and able to keep it running but when I put it in gear it dies. My thoughts are the fuel filter or the fuel pump. This car has pretty much not been driven a lot for the last 20 years. I added a ton of premium fuel and additives over that 1400 mile trip. I am thinking that the fuel filter or the fuel pump are failing. It starts and runs for a few seconds then dies, what do you think?

 

[Bret Schneider]

"I added a ton of premium fuel and additives over that 1400 mile trip"

Those additives likely consisted of a fair amount of alcohol that may have caused any rust in the fuel tank to let loose and find it's way to the carb. Not saying you didn't rebuild the carb correctly, but it's easy to leave some crud in one of the fuel or air circuits. Blowing air and/or carb cleaner directly through those passages is the only way of getting that stuff out sometimes.

 

[Fordication]

"I added a ton of premium fuel and additives over that 1400 mile trip"

Those additives likely consisted of a fair amount of alcohol that may have caused any rust in the fuel tank to let loose and find it's way to the carb. Not saying you didn't rebuild the carb correctly, but it's easy to leave some crud in one of the fuel or air circuits. Blowing air and/or carb cleaner directly through those passages is the only way of getting that stuff out sometimes.

so you are thinking fuel related as well.

 

[pschlosser]

some easy fuel delivery tests.

1. disconnect the fuel line at the carburetor, and direct the line to a container. have a helper crank the engine for 10 seconds or so, and observe the amount of fuel that comes out, and if there is any debris and junk in the fluid. did the stream of fuel flow in squirts, like a heartbeat squirts blood out of a carotid artery in a violent movie. how much fuel dispensed with 10 seconds of cranking? 8 ounces or so?

2. with the AVS carburetor (for example) the fuel fills float bowls. if the engine is dying because of fuel starvation, once it dies, carefully remove the top cover from the carburetor base, and observe how much fuel is in the float bowls. they should be about half-full. but are they dry or really low, like 1/8 to 1/4 inch full.

3. again on the AVS carburetor, with the engine off, when you manually operate the throttle, does fuel squirt out the accelerator pump tubes onto the barrels? is it a nice decent stream?

4. when you "rebuilt" and cleaned the carburetor, did you find obvious junk within it and/or stuff at the bottom of the float bowls.

5. there is screen on the pickup tube inside the fuel tank. if there is a bunch of rust and debris inside the tank, (it would take 8 ounces of debris or more) if could be plugging up the pickup. while it's possible the screen has worn out or torn, chances are, it has not, and the fuel lines are clear. you would have to drain the majority of fuel to remove the sending unit to inspect the screen to see if there is junk caked onto it.

6. prior to the carburetor rebuild, when the engine died, did it die immediately after releasing the key? if so, you may have an electrical, ignition, or ballast resistor issue. how is the health of the spark while cranking? and the cleanliness of the cap and rotor area? points ignition, battery voltage, etc? do the spark plugs look healthy?

 

[Fordication]

some easy fuel delivery tests.

1. disconnect the fuel line at the carburetor, and direct the line to a container. have a helper crank the engine for 10 seconds or so, and observe the amount of fuel that comes out, and if there is any debris and junk in the fluid. did the stream of fuel flow in squirts, like a heartbeat squirts blood out of a carotid artery in a violent movie. how much fuel dispensed with 10 seconds of cranking? 8 ounces or so?

2. with the AVS carburetor (for example) the fuel fills float bowls. if the engine is dying because of fuel starvation, once it dies, carefully remove the top cover from the carburetor base, and observe how much fuel is in the float bowls. they should be about half-full. but are they dry or really low, like 1/8 to 1/4 inch full.

3. again on the AVS carburetor, with the engine off, when you manually operate the throttle, does fuel squirt out the accelerator pump tubes onto the barrels? is it a nice decent stream?

4. when you "rebuilt" and cleaned the carburetor, did you find obvious junk within it and/or stuff at the bottom of the float bowls.

5. there is screen on the pickup tube inside the fuel tank. if there is a bunch of rust and debris inside the tank, (it would take 8 ounces of debris or more) if could be plugging up the pickup. while it's possible the screen has worn out or torn, chances are, it has not, and the fuel lines are clear. you would have to drain the majority of fuel to remove the sending unit to inspect the screen to see if there is junk caked onto it.

6. prior to the carburetor rebuild, when the engine died, did it die immediately after releasing the key? if so, you may have an electrical, ignition, or ballast resistor issue. how is the health of the spark while cranking? and the cleanliness of the cap and rotor area? points ignition, battery voltage, etc? do the spark plugs look healthy?

I am going to be busy tomorrow. There was no debris in the bowls of the carb. In fact the only thing I found was loose screws and bolts on every connection. The only thing I did to the vacuum lines was replace one line while driving from Wisconsin. Then when I got up the next day it would not run. So I did replace a few more lines and the large line on the carb on the front of the carb under the fuel inlet, I trimmed about an inch of it off because it was bad on the end. When I took the carb apart there was very little gas in it to start off with. The kit did not provide new floats which I thought was BS since in the past I always had to reset the height on them. I put everything back in as I found it with the addition of one new gasket in the piston step up plunger that was not there before. Per the instructions. As for fuel line pressure there is an inline filter in the line, I will replace it tomorrow and then do the checks you listed. No, the car would turn over and act like it was going to start then die instantly. I adjusted the idle and I can keep it running but it dies as soon as I put it in gear. I am thinking fuel line. Where is that ballast resistor or what does it look like.

 

[pschlosser]

i recommend you seek out the factory service manual. there are links to free PDFs if you search this site or googlfy

 

[Fordication]

i recommend you seek out the factory service manual. there are links to free PDFs if you search this site or googlfy

I have both service manuals but that does not help me. If I cannot find anything in the manual that says carb popping and stalling. So you are thinking that a car that made a 1400 mile trip in 2 days

i recommend you seek out the factory service manual. there are links to free PDFs if you search this site or googlfy

and never once stalled all of a sudden that ballast on the distributor went bad? It acts like it lost timing for no reason. I have worked on these engines my whole life and never seen one go from running fine one day to just running like crap for no reason. Usually there is a reason. So changed the filter and the same large squirt of fuel in the carb like always. It revs up if you keep our foot in it. I guess I can pull the distributor cap off and check the coil but this is annoying. I had reserved today for taking the car to have the transmission flushed and new fluid installed. Not going to happen.

 

[pschlosser]

I have both service manuals but that does not help me. If I cannot find anything in the manual that says carb popping and stalling. So you are thinking that a car that made a 1400 mile trip in 2 days

and never once stalled all of a sudden that ballast on the distributor went bad? It acts like it lost timing for no reason. I have worked on these engines my whole life and never seen one go from running fine one day to just running like crap for no reason. Usually there is a reason. So changed the filter and the same large squirt of fuel in the carb like always. It revs up if you keep our foot in it. I guess I can pull the distributor cap off and check the coil but this is annoying. I had reserved today for taking the car to have the transmission flushed and new fluid installed. Not going to happen.

I was thinking the manual would help you with the ballast resistor location, wiring diagrams, wire colors, etc. and other more common things. And you're right, when it comes to troubleshooting, the manual is not as good as plain old-fashioned engine troubleshooting experience.

I recommend you eliminate a fuel issue first. there may be ignition-related issues giving you grief, but it seems wise to rule out fuel delivery. These are things one need only do once (when taking ownership of a car) and often, only when there is question. But my instinct is, if you had fuel-related issues, you would have had trouble driving the 1400 miles home.

All I'm suggesting is you LOOK at the underside of the distributor cap, rotor and points for obvious signs of wear or trouble.

I don't recall the details of your drive home, but if it was 1400 miles in one go (impressive, if so) the overnight cool-down may have introduced moisture in the distributor, or some other common malady to a 50-year old automobile.

 

[Fordication]

I was thinking the manual would help you with the ballast resistor location, wiring diagrams, wire colors, etc. and other more common things. And you're right, when it comes to troubleshooting, the manual is not as good as plain old-fashioned engine troubleshooting experience.

I recommend you eliminate a fuel issue first. there may be ignition-related issues giving you grief, but it seems wise to rule out fuel delivery. These are things one need only do once (when taking ownership of a car) and often, only when there is question. But my instinct is, if you had fuel-related issues, you would have had trouble driving the 1400 miles home.

All I'm suggesting is you LOOK at the underside of the distributor cap, rotor and points for obvious signs of wear or trouble.

I don't recall the details of your drive home, but if it was 1400 miles in one go (impressive, if so) the overnight cool-down may have introduced moisture in the distributor, or some other common malady to a 50-year old automobile.

No. I know where the ballast resistor is and the ignition coil condenser. After doing some research it would appear that both of those are the most likely culprit. I looked at the underside of the distributor cap and its all new. Rotor and cap are new. So I have the ballast resistor that has 4 terminals instead of 2. I am going to check that. The ignition condenser is another item. Have no idea how to test it without buying a new one.

 

[Fordication]

I was thinking the manual would help you with the ballast resistor location, wiring diagrams, wire colors, etc. and other more common things. And you're right, when it comes to troubleshooting, the manual is not as good as plain old-fashioned engine troubleshooting experience.

I recommend you eliminate a fuel issue first. there may be ignition-related issues giving you grief, but it seems wise to rule out fuel delivery. These are things one need only do once (when taking ownership of a car) and often, only when there is question. But my instinct is, if you had fuel-related issues, you would have had trouble driving the 1400 miles home.

All I'm suggesting is you LOOK at the underside of the distributor cap, rotor and points for obvious signs of wear or trouble.

I don't recall the details of your drive home, but if it was 1400 miles in one go (impressive, if so) the overnight cool-down may have introduced moisture in the distributor, or some other common malady to a 50-year old automobile.

So I think you put me in the right location. Will let you know in a minute if the resistor is bad.

 

[Fordication]

I was thinking the manual would help you with the ballast resistor location, wiring diagrams, wire colors, etc. and other more common things. And you're right, when it comes to troubleshooting, the manual is not as good as plain old-fashioned engine troubleshooting experience.

I recommend you eliminate a fuel issue first. there may be ignition-related issues giving you grief, but it seems wise to rule out fuel delivery. These are things one need only do once (when taking ownership of a car) and often, only when there is question. But my instinct is, if you had fuel-related issues, you would have had trouble driving the 1400 miles home.

All I'm suggesting is you LOOK at the underside of the distributor cap, rotor and points for obvious signs of wear or trouble.

I don't recall the details of your drive home, but if it was 1400 miles in one go (impressive, if so) the overnight cool-down may have introduced moisture in the distributor, or some other common malady to a 50-year old automobile.

Just checked it. 1.7 ohms and 12.8 oms and the 12.8 ohms is bouncing all over the place. Will not settle down. Bad resistor. I am thinking of buying the condenser as well just to make sure.

 

[pschlosser]

No. I know where the ballast resistor is and the ignition coil condenser. After doing some research it would appear that both of those are the most likely culprit. I looked at the underside of the distributor cap and its all new. Rotor and cap are new. So I have the ballast resistor that has 4 terminals instead of 2. I am going to check that. The ignition condenser is another item. Have no idea how to test it without buying a new one.

the condenser is kind of optional. mostly to suppress ignition noise on the AM radio. If you suspect its faulty, just disconnect it for a time until you have things resolved.

 

[pschlosser]

the ballast resistor can break. it becomes brittle over time, and not an uncommon thing to fail at least once in 50 years. the ones with 4 terminals are the same, more or less, as the 2-terminal ones. the 4-terminal was found on 1972 and later cars. make sure the spade terminals connecting to the ballast resistor are not worn and loose. we want a solid connection, there. while cranking the engine, the ballast resistor is bypassed. once you release the key to the run position, power to the coil is then feeding through the resistor. its resistance varies with heat. as the engine RPM rises, the number of times it fires (per second) increases, and the resistance varies accordingly. testing it when its cool, it should have a solid reading. if it varies with handling and jiggling, it may indeed be busted. go buy a spare and test. if it later turns out it is fine, it's often wise to have a spare in your glove box, anyway.

 

[Challenger RTA]

This car has pretty much not been driven a lot for the last 20 years.

My thoughts are the fuel filter or the fuel pump.

Thats where I would start. Change the fuel filter and check fuel pressure. Then a basic tune up even if you just remove plugs, cap, rotor and clean.