71 Dauntless Ignition Cuts Out After 20 Minutes

Ok, after driving for about 20 minutes all of a sudden my Jeep starts acting super weird. First time, it was like entirely losing spark. This time, it was more gradual. Felt like it got no fuel, died, hard to start, then the ignition switch did nothing to the starter. I checked power to the starter, and to the solenoid. There was no power to the solenoid with the key turned to start it. With the key on, the lights and everything go on but when you turn it, nothing happens. Lights go dim from power being sent somewhere but nothing happens. No clicks. Then, you let it sit for half an hour and it starts right up.
Possible it's a faulty ignition switch? No wires are loose that I can tell. Battery cables are recently replaced.

 

Also checked the ballast resistor, there was power to both sides when key was put in start position

 

Make sure the plug is firmly pushed into the back of the ignition switch.

 

It is. It's done this same exact thing twice. Cuts out after driving for a bit, let it cool down and it works again.

 

Is your battery good? Lights can still come on without a battery >12.5 volts needed to crank and sustain a running engine

 

When my ignition switch works it cranks over perfect.

 

Wires are not lose. In my opinion it has nothing to do with anything lose, has to be a component sensitive to heat since I can keep recreating the problem. Has nothing to do with tightness of battery, switches plugged in, or lose wires.
I'm new to old ignition systems, could a ballast resistor cause issues like this?

 

Had a john Deere rider did exact same thing. Drove me nuts. Bad ignition switch, would get warm sputter and die out. Wait 10 and it would fire right up. I jumped around it until end of mowing season

 

engine shutting off after 20 minutes . coil or condenser . if it's still getting fuel
starter problem sounds like a starter solenoid . replace

I had a similar problem with starting . but I would get a test light to light in start position . just wouldn't crank . but would with a remote starter button . added a ford starter solenoid ahead of solenoid on starter . ign/start only supply's power to ford solenoid . bigger wires on lugs to feed stock solenoid . no more voltage drop from switch . learned this from vw crowd . just something to think about

 

First, I would look that there is gas in the float bowl when it cuts out. Next I would hot-wire the ignition and see if the problem goes away. This will separate the ignition switch circuit from the problem. If it still cuts out when hot-wired, I would suspect the ignition coil next. Try cooling the coil with an ice pack or BlueIce or something.

 

Interesting! Actually I think i may be getting power to the solenoid after all, I honestly think my test light wasn't grounded good when I checked it

 

Maaaaaybe I have two issues, that would explain ignition cutting out and the starter issue.
What's the best way to hot wire spark? Battery to ballast resistor input? Or straight to coil(but that'll fry points quick right?)

 

You can hot wire for 20 minutes without trouble, but since the ballast resistor is right there, may as well go to it.

 

So, wire it to the input of the ballast resistor right?

 

Okay. But a poor or corroded connection could make resistance, which then heats up. As it heats up, resistance increases. Which creates more heat, etc.
In the end (after twenty minutes or so?) there is is insufficient power reaching the coil.

Just a thought.

 

I never thought about it that way! I guess anything could be possible on something this old. I should mention it recently started doing this. I had the Jeep last year, ran it for an hour straight no issues(first day I bought it, after sitting it started right up and I ran it for quite a while) and I finally just redid the brakes and started driving it and this issue is new.

Yesterday I jumped the ignition(battery to ballast input) and 5 minutes in it just ran like garbage. Gave it gas, carb just sucked air. Removed my jumper, ran perfect.
I also have never had an issue with fuel delivery. When I give it gas the fuel spray is beautiful

 

Or maybe somehow there was a clog at the pickup from stuff in the tank and when I shut off the Jeep wherever was clogging it dropped out when the fuel pump stopped sucking. There are so many possibilities... Maybe I try jumping the ignition again.

Thank you guys for the excellent advice, it's making this a lot less stressful to figure out!

 

Ok, I think the running bad that happened when I jumped the ignition is solely coincidence. I started it up this morning, ran great for a minute then just sucked air and died. Starting fluid got it going and still would only idle. Put a gallon of gas in and it ran good.
My gas cause is shot and apparently a little sloshing around is making the fuel pump lose prime when low (understandable!)
So, I'll be retesting it with a jumped ignition switch in about 3 hours now and hopefully get more accurate results.

 

You can run from a can of gas on the cowl, with a fuel hose direct to the carburetor. Siphon pressure is enough to fill the float bowl.