'66 starting problems

Thinginator

Thinginator

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Oct 30, 2019
Thunderbird Year
1966
It's getting pretty cold around here (as low as 14 degrees), and lately I've been having trouble getting my '66 Thunderbird started in the morning. On the first or second turn of the key, it fires right up, but then idles slower and slower until eventually dying. Pumping the gas pedal doesn't help, either. After that, the starter goes a lot slower than it ought to, and keeps getting slower until no longer working. If I let it sit for a few hours and try again, it does the same thing. Even after putting the battery on a trickle charger overnight, it did the same thing. Autozone said the battery seems to be fine, but could they be wrong? Any advice would be appreciated, as I miss driving this car and want to get it back on the road as soon as possible.
 
Sounds like fuel starvation to me - have you checked the fuel pump? Has the gas been in the car for a long time, if so you could have water in the fuel which would freeze in that sort of temperature and block the carburetor jets, Ethanol can result in water production. Batteries do not like very cold weather , will provide fewer cranking amps even when fully charged and 19 degrees is cold! I used to place a 100 watt lightbulb on top of the engine and close the hood to raise the temperature . Might be worth installing a block heater.
 
The starvation problem has already been addressed, but for the starting;;make sure all grounds are clean, especially the battery cable to block.
 
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It's getting pretty cold around here (as low as 14 degrees), and lately I've been having trouble getting my '66 Thunderbird started in the morning. On the first or second turn of the key, it fires right up, but then idles slower and slower until eventually dying. Pumping the gas pedal doesn't help, either. After that, the starter goes a lot slower than it ought to, and keeps getting slower until no longer working. If I let it sit for a few hours and try again, it does the same thing. Even after putting the battery on a trickle charger overnight, it did the same thing. Autozone said the battery seems to be fine, but could they be wrong? Any advice would be appreciated, as I miss driving this car and want to get it back on the road as soon as possible.
is it 14 fahrenheit or celcius?
 
Sounds like fuel starvation to me - have you checked the fuel pump? Has the gas been in the car for a long time, if so you could have water in the fuel which would freeze in that sort of temperature and block the carburetor jets, Ethanol can result in water production. Batteries do not like very cold weather , will provide fewer cranking amps even when fully charged and 19 degrees is cold! I used to place a 100 watt lightbulb on top of the engine and close the hood to raise the temperature . Might be worth installing a block heater.
Thanks for the advice! I know it's not the gas, because this car is my almost daily driver, so the gas is usually never more than a couple weeks old. I don't think it's the fuel pump, because the previous owner replaced it before I bought it. I'll probably check it anyway, though, just to be sure. The battery is the thing I suspect the most, since I don't know how old it is and it is pretty dang cold in the mornings right now... I think I might replace it with one that has slightly higher amperage, since it's already a bit lower amperage than it could be and even less due to the cold. I know someone with an engine blanket they aren't using, so I'll see if I can use that, too.
 
You seem to have two unconnected problems. First the car starts but slowly dies , this is a fuel starvation issue and has nothing to do with the battery. Second, the engine dies and you try and restart it but it will not start and the starter dies due to the battery running down. If you fix the first problem, you won’t have a second problem unless the battery is tired or the starter is old and drawing too many amps . So it’s the fuel pump, the fuel filter or the carburetor accelerator pump which is a common problem. Not expensive to just change those issues out. A block heater would be a good idea.
 
You seem to have two unconnected problems. First the car starts but slowly dies , this is a fuel starvation issue and has nothing to do with the battery. Second, the engine dies and you try and restart it but it will not start and the starter dies due to the battery running down. If you fix the first problem, you won’t have a second problem unless the battery is tired or the starter is old and drawing too many amps . So it’s the fuel pump, the fuel filter or the carburetor accelerator pump which is a common problem. Not expensive to just change those issues out. A block heater would be a good idea.
Interesting. Do you think it could also be an issue of the choke being in the wrong position? I know very little about tuning carburetors. Since it's in a position where it will eventually start in most temperatures, I've left the carburetor alone, but could it be that the choke is so far in the wrong position due to cold that it's preventing the engine from getting enough fuel now?
 
Well that’s a thought , the choke should be closed when you start it up, and then slowly open as the engine warms up. If the choke was to open prematurely , the engine would die, as you describe. I am more familiar with Pontiac 400 GTO engines that have a spring close to the exhaust that expands and releases the choke. Suggest you take the air cleaner off and watch the choke mechanism to see whether it is working as it should. If it were go stay closed, the engine would also quit . So, your thought is a good one. Are you sure the fuel pump is working and the carburetor fuel filter is clean. The extreme cold weather might affect the pump diaphragm . When the engine starts to stall, adjust the butterfly valve/choke to see whether this solves the problem in which case the choke pull off may be the issue. BTW, you should move go FL!
 
My 1966 Thunderbird is experiencing fuel starvation problems. When I start the car, it initially fires right up, but then idles slower and slower until dying, and afterwards no amount of cranking will make it start, even when jump starting it. Is it more likely that the problem is with the fuel pump, or with the fuel filter? And how should I replace it? I've heard that they're easy and cheap to replace, but since I'm a beginner mechanic, I still don't know how to replace those things, or even where they're located. (My engine is the 390, by the way.) Any advice would be appreciated.
 
fuel pump is on lower left side of engine near the front. some of these pumps have a screw on filter, otherwise filter will be in fuel line in front of carb. try diconnecting fuel line to carb and turning engine over a little and see if fuel comes out of the line.
 
fuel pump is on lower left side of engine near the front. some of these pumps have a screw on filter, otherwise filter will be in fuel line in front of carb. try diconnecting fuel line to carb and turning engine over a little and see if fuel comes out of the line.
filters are cheap and easy to replace. i would try that first
 
I know someone had a similar problem not too long ago, and I was hoping that thread would provide answers, but their solution was a possibility I'd already ruled out, so... Gas isn't getting to the carburetor. We removed the lines to test the fuel pump, and it seems to be pumping gas. The carburetor smelled like gas, but looked dry. The carburetor is an aftermarket Edelbrock four-barrel, and the replacement pump looked a bit different from the one that was originally on there, with a filter on the bottom rather than further up on the line. As a result, in order to make the fuel lines reach with stuff I had on hand, I had to use the that extra filter, so there is one more than necessary, though it seemed like there weren't any blockages in it. The symptoms seem like vapor lock, but the engine's far too cold for that. Could the third fuel filter be adding too much resistance even though it's not clogged? Could there be a blockage in the metal fuel lines or the tank? Could there be a needle in the carburetor that's stuck? I'm so confused. Any ideas on what it could be and how to fix it?
 
If you disconnect the fuel line from the carburetor, and crank the engine (coil disconnected) then a lot of gas should spurt out of the fuel line. If not, and if there is gas in the fuel tank, then fuel pump is likely toast. A clogged fuel filter may impede the flow of gas, but not block it entirely. If fuel line exit from fuel tank is completely blocked, then you may have found Al Capone's missing road maps.
 
Removing the fuel line is very dangerous this is not a recommended for troubleshooting, under any circumstances. Takes one spark!!!!!!!!!
 
Removing the fuel line is very dangerous this is not a recommended for troubleshooting, under any circumstances. Takes one spark!!!!!!!!!
Nonsense. Stick end of fuel line in a jar and bump the starter, that's all it takes. Disconnecting coil ensures engine won't start. End of fuel line, being next to carb and in jar, will not be near source of ignition.
 
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