Bare with me here fellas (this will be long), but the more information I give the better you can help. My 51 F1 has a 289 with an Autolite 2100 carb. Been running flawlessly for the past couple of years. I drove it approximately 20 mins earlier today with no problems, but then all of a sudden it died pulling into Lowes. At that point I could only get it to crank with the pedal to the floor. Release the throttle at all and it would die. No sputter, no roughness, just off (as if you pulled the coil wire). After about an hour I was able to get it to start and idle fine, revved fine, etc. I started to head back home, and before I left the parking lot it died again. I was able to get it started again by flooring it, and after releasing the throttle it idled again too. I popped the hood just to see if I could see anything obvious, and didn't see anything that was wrong. I shut the hood, and as soon as the hood closed it shut off again. This made me think maybe it's electrical? I checked the battery terminals, and voila the negative was on but could be pulled off by hand. I tightened that down, it cranked without having to floor it and idled fine. I let the engine run for a good 5 mins in the parking lot before daring to get out on the street. I thought perhaps I found the culprit. At that point I decided to try to make it home. I made it about a mile before it died again (this time at a busy intersection). I couldn't get it started now even flooring the throttle. I was able to get a push from some nice cops into a nearby lot. While waiting for the tow truck I loosened the fuel line to the carb to make sure there was fuel flowing, and it was (there was also pressure). I then took the top of the carb off to make sure the float and needle weren't stuck, and that there was fuel in the bowl. Float level looked good. Needle moved up and down. I didn't see any debris in the bowl period. I put it back together, and tried to start it. It would start with full throttle, but die as soon as I let off of the gas at all. There's no gas coming out of the carb vent so I don't think it's actually flooding. After getting a tow home and rolling it off the truck it started right up with NO throttle and idled. I was able to maneuver into the garage, and then it died again. I was able to crank it again immediately with NO throttle and let it idle for 2 mins before it died yet again. I don't even know where to start now. When it dies all the gauges, and lights still function. There's no interuption in accessories (lights don't flicker when it happens). They dim a little since the alternator stops spinning but that's it. Because it will start sometimes with no throttle, but then other times only with full throttle it makes me think maybe it isn't electrical. If the coil or condensor were going bad I don't think the amount of throttle would make any difference. Again there's no sputtering or roughness when it dies. When I drove it that 1 mile it drove just as good as it always did until it died.

You guys have any suggestions on where to start?

 

I had a problem that was similar. I had installed a electronic ignition and while putting the coil back on I didn't tighten the clamp and the coil vibrated down so that it touched the exhaust header. When the motor warmed up the coil got hot and broke down. It reminds me of everything you are describing. After mine cooled off it ran great so all I had to do is raise the coil and clamp it down properly. If a coil is bad it does the same thing. Just my thoughts good luck finding your problem.

 

Should be able to test coil with a VOM meter when it has died or exchange it.
Have you checked the fuel filter?

 

Are you sure your ignition sw is good. I had that problem all this winter
on my sander a 1950 F6. Same symptoms, It would just die usually in the
middle of the road. Luckly I had some wire under the seat and snaked it
from the coil to inside and twisted it to a live source and got through all
those blizzards without fail. Switches do go bad. Odd enough now summer
it runs fine without the jumper. My Switch may not like the cold I guess.
So try jumping it. Or ign sw wire to coil has a problem somewhere...
sam

 

Alright I bought a new coil today and installed it. It started right up afterwards, and I let it idle for a few mins. I thought maybe it was fixed but then it died. I was able to immediately start it again but it died 10 seconds later. I immediately took the top off the carb, and the float level is spot on. I pressed down on the float and gas comes out of the needle with good pressure so that eliminates a fuel problem. I took out the condenser and touched the red wire to the metal case. There was no spark. I then hooked an ohm meter to it, and there's no resistance. Not zero, the meter shows an open circuit. Is that right?

 

The condenser is a capacitor. Most likely will always show as open, depending on your meter and settings.

Is the wire from your ignition switch to the coil good. Could it be frayed going through the firewall and intermittently touching ground?

 

Ah ok. It looks new. If you sold it to me in a box, and said it was new I wouldn't doubt it for a second that's how clean it is. Points, cap, and rotor all still look new too.

I checked the ignition switch itself (and all the wires on it), and everything looks good. No obvious signs of a problem or short there. I did not check where it passes thru the firewall. I'll check that tonight. Thanks

 

You can simply check it to ground with a meter and wiggle it around, see if it is shorted intermittently.

 

I didn't find any shorts by wiggling the wires. However, I did find if I jiggle the key slightly while in the on position the gauges loose power and come back. I suspect there's a problem inside the switch. Thanks for your help! I probably would of replaced just about everything else attempting to fix it and not even thought about the switch if you hadn't commented.

 

Just one other thought. A friend of mine had similar intermittent run problems. He replaced coil, then ignition switch, still had the same problem. He decided to replace the points and condenser and while doing that found the actual problem. The little ground strap that connects to the breaker plate was broken. Once he repaired it. All was good.

 

I think I'd find a stick or something non-conductive, start the engine and start moving wires around with the stick to see if I could get it to die...I just read that you think it's the ignition switch-that sounds like a good possibility to me.

 

Yep, sounds like a bad switch, as big job said in post #4. Good luck. Hope that's the problem.