Stalling problems with the '68 ... Electrical? Need input

[Sacbill]

Just installed a new Summit 600cfm carb on the '68 and have been driving it around.

Suddenly, the following problem crops up: Driving down the road, the car stalls. Drift to a stop, put it in neutral/park, start it up. (Sometimes it doesn't start right up, but usually does) Idles fine, then I put it in drive. Dies immediately. No "sputter sputter" like a a fuel thing. Just dies.

Alternately: Driving down the road, car stalls. I notice the electric fan is not running. After about a 1/2-second, the electric fan is running again. I'm able to start the car (neutral or park). I got to a point with the stalling that it was getting repetitive, so I just had it towed home to sort it out.

Seems like an electrical problem to me, and I'm wondering where and what to start diagnosing.

Some further info on the car's electrical system:
* Spal electric fan
* Powermaster Single-wire alternator
* Screw on disconnect at the ground terminal of the battery.
* No cranking issues on these restarts, so it doesn't sound like a low battery.

Thanks in advance for the input!

 

[66benchcoupe]

Bad ground? Check the wires at the coil, a poor connection there could stop the engine running due to vibrations.

Where does the SPAL fan get its signal?

Robert

 

[nymustang]

Sounds like a similar problem I had with my DD. At first they thought bad ground, turned out to be a broken wire in a wire harness connector for the Alt. Enough vibration would wiggle it loose. Good luck diagnosing.

 

[Anonymous]

Yeah, I would check the battery terminals (clean) and main grounds, pay close attention to the engine block to chassis ground. let us know

 

[AzPete]

Did this just start with the change of the carb? Maybe a pinched wires from the install. If it is just since the carb install, I would look at that as a problem first. Will it die while idling in the driveway? Does it seem to die at a certain speed....engine or forward speed? Wind could be moving a loose wire. When I had problems with the SPAL relay fan, it would not stop the engine....the relay got hot and failed to operate and remained open.

 

[gtscode]

I wouldn't overlook fuel as a potential issue.

 

[Neglected68]

How did you wire up the electrical choke? Could that wire be causing a short?

Full disclosure: I still need to wire my choke up on my Summit carb install, so I am happy to see how you did yours.

 

[cmayna]

I kind of agree with the others above regarding something electrical wise might have gotten loose during the carb install. If it was fuel, it would be pretty easy to diagnose. But since you mention that the fan wasn't on when it should be then I'd stay focused on electrical.

 

[apollard]

Don't overlook a worn ignition switch. I had one that would do this, and it drove me crazy. I finally figured out that if I wiggled the switch a certain way, it would die. However, not everything died. Can't remember what stayed on, but I'm sure Mid could tell me what should have stayed on.

Changed the switch, no more problems.