1962 Thunderbird. Hard to start after warm

[Rob C]

I have my 1962 convertible running and on the road for the summer. It starts right up when I take it out after a night in the garage. Runs well and had a new carburetor a year ago. Fuel pump newer as well. But if i drive for 20-30 minutes or so and it is all warmed up. After a 15-20 minute stop, it is tough to start. It turns over and over, i then pump and finally floor the peddle and then it come to a roar. Hope there is a simple idea for what to do. Thanks

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[Ward 57]

Most likely vapor lock. The fuel is vaporizing in the fuel lines. Trace them and make sure they aren't running too close to any part of the exhaust system. You also might want to wrap some insulation around them in the engine compartment. you might check on the status of the carburetor spacer. and make sure the fuel bowl on the carburetor isn't boiling dry from a hot intake manifold.

 

[doug7740]

I used to have the same problems that you are having until I started using 100% gasoline in my Thunderbird. Here is a link to see where you can buy 100% gasoline in your state:

https://www.pure-gas.org

doug7740
1955 Thunderbird Blue

 

[skyshark58]

Check point gap and coil.
Mike

 

[64ZCODE]

I wonder if your fuel pump is up to snuff. Might be a good idea to do a pump test and check fuel pressure. I chased an intermittent no start problem for a month on my '64 and it turned out to be a dodgy fuel pump.

 

[mistfr]

Your engine/carb is fine! Symptoms can be mitigated with a fuel return line and an electric pump but it's not really necessary...

 

[DennisC]

I have my 1962 convertible running and on the road for the summer. It starts right up when I take it out after a night in the garage. Runs well and had a new carburetor a year ago. Fuel pump newer as well. But if i drive for 20-30 minutes or so and it is all warmed up. After a 15-20 minute stop, it is tough to start. It turns over and over, i then pump and finally floor the peddle and then it come to a roar. Hope there is a simple idea for what to do. Thanks

Hi Rob, A couple of questions and some ideas. What engine is in it? 390 with A Ford 4 bbl carb? What fuel is in it? Assuming Your battery is strong and it is cranking fine when hot, Make sure a good fuel is in it...such as Shell V power Nitro or Exxon/Mobil supreme Premium. Second, Next time you are out and running it and after it is warmed up, shut it off...remove the air cleaner and verify the choke is wide open. When you say you have to put it to the floor and hold it there to get it started, that’s a sign it’s flooded or the choke is not opening. How many times dId you pump the gas pedal when hot starting it, before having to hold the pedal to the floor to start it? Finally if those issues are not the problem I would check the float levels in the carb you replaced. It could have a high float level and it is flooding the engine. Do you small gas when it starts and does black smoke come out the tail pipe when it finally fires up? good luck.

 

[Rambler63]

I have my 1962 convertible running and on the road for the summer. It starts right up when I take it out after a night in the garage. Runs well and had a new carburetor a year ago. Fuel pump newer as well. But if i drive for 20-30 minutes or so and it is all warmed up. After a 15-20 minute stop, it is tough to start. It turns over and over, i then pump and finally floor the peddle and then it come to a roar. Hope there is a simple idea for what to do. Thanks

Youre going to want to make sure the idle/air mixture screws are dialed in. x2 on sounding like its getting flooded. Try insulating or moving fuel lines away from the block to help rule out vapor lock.

 

[Rob C]

Hi Rob, A couple of questions and some ideas. What engine is in it? 390 with A Ford 4 bbl carb? What fuel is in it? Assuming Your battery is strong and it is cranking fine when hot, Make sure a good fuel is in it...such as Shell V power Nitro or Exxon/Mobil supreme Premium. Second, Next time you are out and running it and after it is warmed up, shut it off...remove the air cleaner and verify the choke is wide open. When you say you have to put it to the floor and hold it there to get it started, that’s a sign it’s flooded or the choke is not opening. How many times dId you pump the gas pedal when hot starting it, before having to hold the pedal to the floor to start it? Finally if those issues are not the problem I would check the float levels in the carb you replaced. It could have a high float level and it is flooding the engine. Do you small gas when it starts and does black smoke come out the tail pipe when it finally fires up? good luck.

Thanks Dennis
Yes it is a 390 with 4bbl. I have filled it with Ethanol free gas last couple of times. 90 octane. Not sure if that makes any difference.
I will do the check on the choke. I runs pretty hot but never boils over. I am going to check 2 things. One is the ratio of antifreeze (i think it is way more then 50%) and two, to change the radiator cap from 18 lb to the recommended 13 lb.
When i try to start it when hot, i first turn it over with no pumping. (when cold that is the way it starts) When it won't go, i pump twice to the floor while turning over, then finally hold pedal to floor. Then it starts with a pretty big puff of black smoke and a smell of gas. . Thanks for the advice.

 

[DennisC]

Thanks Dennis
Yes it is a 390 with 4bbl. I have filled it with Ethanol free gas last couple of times. 90 octane. Not sure if that makes any difference.
I will do the check on the choke. I runs pretty hot but never boils over. I am going to check 2 things. One is the ratio of antifreeze (i think it is way more then 50%) and two, to change the radiator cap from 18 lb to the recommended 13 lb.
When i try to start it when hot, i first turn it over with no pumping. (when cold that is the way it starts) When it won't go, i pump twice to the floor while turning over, then finally hold pedal to floor. Then it starts with a pretty big puff of black smoke and a smell of gas. . Thanks for the advice.

You’re welcome Rob. Thanks for the reply. Based on your info, I am wondering if you have a fuel filter and if it was replaced recently? The 90 octane, ethanol free fuel is a bit low For your engine. The 390 likes the high octane gasoline’s. I’d suggest you try the Shell or Exxon/Mobil. If you are concerned about the ethanol, my recommendation is to do what I do and use Stabil 360 at each fill up. It eliminates the moisture in the gas left by the ethanol and extends the life of the gas if you store the car over the winter. I’ve been using it for years in my 1967 Mustang GT 390. Other considerations include checking the timing and the condition of the ignition wires, plugs, points and condenser. Finally, depending on your budget and how hands on you like to be, you might consider alternatives to the current carb. If memory serves me your engine came with a Ford Autolite 4bbl. See attached pic. Not a great carb. There are lots of alternatives like Edelbrock and Holley. I use a Holley on my Mustang. But I would first make sure my ignition system and fuel filter check out. Good luck.

 

[Rob C]

You’re welcome Rob. Thanks for the reply. Based on your info, I am wondering if you have a fuel filter and if it was replaced recently? The 90 octane, ethanol free fuel is a bit low For your engine. The 390 likes the high octane gasoline’s. I’d suggest you try the Shell or Exxon/Mobil. If you are concerned about the ethanol, my recommendation is to do what I do and use Stabil 360 at each fill up. It eliminates the moisture in the gas left by the ethanol and extends the life of the gas if you store the car over the winter. I’ve been using it for years in my 1967 Mustang GT 390. Other considerations include checking the timing and the condition of the ignition wires, plugs, points and condenser. Finally, depending on your budget and how hands on you like to be, you might consider alternatives to the current carb. If memory serves me your engine came with a Ford Autolite 4bbl. See attached pic. Not a great carb. There are lots of alternatives like Edelbrock and Holley. I use a Holley on my Mustang. But I would first make sure my ignition system and fuel filter check out. Good luck.

That is great info. I will try some of the things and let you know how I do.

 

[sombb]

Hello,

Posting here as symptoms on my 1963 Landau are similar. In my case I get one start a day ;-0, and the car stutters the quits after approximately 10 minutes. Very frustrating that I can't even get to the Ford factory manual start point, 30 minutes at idle to make adjustments.

I have installed new: start switch, starter relay, fuel pump, spark plugs, rebuilt Autolite 4100 carb, fuel pressure regulator set to 4.5 psi. The previous owner installed a Pertronix ignition, which I've matched with a Pertronix FlameThrower coil. I have cleaned all fuel lines back to the tank. Timing is properly set to spec, 8 degrees BTDC (tho' had to be set at way above idle speed, see below). Electric choke added, set to center hash mark on the choke dial.

I'm not certain "idle" is the right term, as the "idle circuit" is not the prime operator, when the Bird won't idle below 2000 rpm. I must screw down the idle speed screw way past what I'd normally think reasonable, to its max. On a start several days ago, I was able to idle with settings: 4 degrees BTDC, 750 rpm via idle speed screw, then on to idle mixture screws. The mixture screws in or out (from specified 1 1/2 turns out) made absolutely no difference in idle speed, including 100% closed which should, but did NOT, kill the engine.

So, trying to get to 30 minutes, full operating temp, the car runs for 10 minutes, rumbles for 10 seconds, then completely quits. Then the car grinds the starter until the battery must be re-charged, and will not re-start. Wait overnight, and my "one start a day," rinse and repeat. Any suggestions?

 

[74 Harley]

Sounds like you have a vacuum leak, and a big one. Maybe even a cracked manifold. Also check what you have for end seals under the manifold, cork is not a good thing. On these engines I only recommend using a silicone bead to seal the ends of the manifold. Good luck and keep us posted.

 

[64ZCODE]

Hello,

Posting here as symptoms on my 1963 Landau are similar. In my case I get one start a day ;-0, and the car stutters the quits after approximately 10 minutes. Very frustrating that I can't even get to the Ford factory manual start point, 30 minutes at idle to make adjustments.

I have installed new: start switch, starter relay, fuel pump, spark plugs, rebuilt Autolite 4100 carb, fuel pressure regulator set to 4.5 psi. The previous owner installed a Pertronix ignition, which I've matched with a Pertronix FlameThrower coil. I have cleaned all fuel lines back to the tank. Timing is properly set to spec, 8 degrees BTDC (tho' had to be set at way above idle speed, see below). Electric choke added, set to center hash mark on the choke dial.

I'm not certain "idle" is the right term, as the "idle circuit" is not the prime operator, when the Bird won't idle below 2000 rpm. I must screw down the idle speed screw way past what I'd normally think reasonable, to its max. On a start several days ago, I was able to idle with settings: 4 degrees BTDC, 750 rpm via idle speed screw, then on to idle mixture screws. The mixture screws in or out (from specified 1 1/2 turns out) made absolutely no difference in idle speed, including 100% closed which should, but did NOT, kill the engine.

So, trying to get to 30 minutes, full operating temp, the car runs for 10 minutes, rumbles for 10 seconds, then completely quits. Then the car grinds the starter until the battery must be re-charged, and will not re-start. Wait overnight, and my "one start a day," rinse and repeat. Any suggestions?

After your "one start", try squirting starter fluid down the carb throat and then see if it'll kick over. If it does, then the engine is starving for gas for some reason.

If that's the case, then possibilities: accelerator pump isn't pumping (easy to check), or rebuilt carb isn't doing it's job. Also, 4.5 psi fuel pressure sounds too low to me. The 390s run fine on the pressure straight from the fuel pump, which I think is 7 psi. Also, you mention the electric choke added, have you checked to make sure that at cold start the choke butterfly is completely closed?

 

[sombb]

Sounds like you have a vacuum leak, and a big one. Maybe even a cracked manifold. Also check what you have for end seals under the manifold, cork is not a good thing. On these engines I only recommend using a silicone bead to seal the ends of the manifold. Good luck and keep us posted.

Thank you for responding. On inspection of the distributor I found burnt contacts on all posts and on the rotor. I replaced both, went back to the “working coil” instead of Pertonix Flame Thrower. Car started…and then I found it: major vacuum leak, on the outside of cylinder #5 at the valve gasket.

All signs pointed to vacuum leak and indeed as you wrote, “a big one.” The fix is clear, so onward.

 

[sombb]

….Also, 4.5 psi fuel pressure sounds too low to me. The 390s run fine on the pressure straight from the fuel pump, which I think is 7 psi. Also, you mention the electric choke added, have you checked to make sure that at cold start the choke butterfly is completely closed?

Thanks for the reply. I found a major vacuum leak. I checked the Ford Factory Manual which specifies 4-6 psi. Parts gurus said new fuel pumps can be a quality control crap shoot, so with the regulator inline, I will try 4.5 for now, dial up or down to find the sweet spot. The choke opens fully, so that seems okay.

Great points, all a help. Vac leak was always the logical answer, just a bunch of work ahead to remedy that.

 

[Frankie the Fink]

Any decent vacuum gauge serves double duty as a fuel pump pressure gauge too - read the instructions on how to peform the test, it takes 5 minutes, Pressure is NOT volume so do a volume test as well. 7 psi is too high for most carburetors and can push needle valves off their seats 4.5 to 5.5 psi is about where you want to be. A vacuum leak can be found by passing an UNLIT common handheld propane torch around likely spots with the engine idling, carb base gasket, intake manifold, etc.. If the engiine speeds up at any point from sucking in propane then that's your leak.

 

[Ward 57]

Any decent vacuum gauge serves double duty as a fuel pump pressure gauge too - read the instructions on how to peform the test, it takes 5 minutes, Pressure is NOT volume so do a volume test as well. 7 psi is too high for most carburetors and can push needle valves off their seats 4.5 to 5.5 psi is about where you want to be. A vacuum leak can be found by passing an UNLIT common handheld propane torch around likely spots with the engine idling, carb base gasket, intake manifold, etc.. If the engiine speeds up at any point from sucking in propane then that's your leak.

Carb cleaner will do the same for those who don't have a torch. Mine is self igniting so that won't work.

 

[sombb]

…and then I found it: major vacuum leak, on the outside of cylinder #5 at the valve gasket.

All signs pointed to vacuum leak and indeed as you wrote, “a big one.” The fix is clear, so onward.

Oooops! Major error. The active major leak was at the exhaust manifold gasket, NOT the intake manifold.

Can a big exhaust gasket leak spoil starts? Idle? Indicate anything about vacuum?

 

[Ward 57]

Oooops! Major error. The active major leak was at the exhaust manifold gasket, NOT the intake manifold.

Can a big exhaust gasket leak spoil starts? Idle? Indicate anything about vacuum?

Nope, That's all after the ignition cycle. Will have no effect on intake and ignition cycle. Look before that.