Engine Quits Under Electrical Load

Brand-new problem today.

Was sitting at an intersection in neutral at warm idle, light turned green, I pressed the brake pedal to shift into drive and the engine quit. After it quit, I shifted into park and started the engine with no problem. I pressed the brake to shift into drive again and the engine quit again. This time I shifted into neutral (without pressing the brake), started the engine, shifted into drive and took off.

Usually the B+ gauge is steady around 14+, but now the gauge needle was slightly pinging back and forth (like it was being "plucked"), then wildly pinging back and forth anytime an electrical load was being used; pressing the brakes, opening the top, etc. Opening the top shuts the car off every time.

Initial visual showed nothing wrong, no burning odors, nothing melted or too hot. All grounds (to chassis) were checked/cleaned/tightened and fusible links were checked/replaced a year ago when it blew a fusible link. Battery/cables look fine, accessory cables look fine, nothing has changed. Ignition is older version MSD distributor w/box and there are no other electrical loads on the car that aren't factory. All lamps interior/exterior work, signals work, etc.

I can guess, but has anybody experienced this before?

I barely got it home and it will see the mechanic in a few weeks.

I appreciate your help...

 

Sounds like your idle speed is too low . Why would you be sitting at a red light in Neutral ????

 

Check grounds to the engine, body and battery

 

^^^^^ What Briz says!

I would start with the battery.

 

As well as the above,
Pull and clean posts and clamps.
Check the battery cable and wires on the starter solenoid.
Check the alternator and regulator wiring/connections.

If you run the car with loose, corroded or poor condition cables/wiring, and resistance is too high, you risk smoking the alternator or having a wire fire.

I pull, clean and inspect all of these twice a year. (But I am running 140+ alternators on both my cars)

 

I would vote for the battery being very low or almost dead and the MSD system not liking the low voltage.

 

Warm idle in drive is a perfect 750 - 850 rpm and neutral is about 75 rpm above that.

With 500HP and a car that WANTS to launch at every opportunity, I use neutral to rest my right foot once in a while instead of standing on the brake to keep it from inching forward...

 

All are great suggestions and will be looked at.

Engine is well cared for, visual showed zip wrong/corroded/loose, etc. Tune up about six months ago with new battery, plugs, wires, cap & rotor button.

The ignition system/engine electrical had a good inspection/repair when the battery failed/fusible link blew. All the engine compartment grounds were inspected, cleaned and replaced. So I'm confident with those, but all that will be gone over again.

My money is on bad alternator...bad, bad alternator...gonna be a few weeks though.

 

Oh . That wasn't explained in the original post . Just that it stalled at lights and voltage was playing games .

 

Leaking brake booster?

 

Why wouldn't you? I always put in neutral at long lights. Why heat up the trans leaving in gear?
Sure alot of people do even in 1hr backups....then they wonder why their trans fails.....

 

Like the guys said... check the battery! Age-How old is it? Volts? Check Cold cranking amps? Alternator - is it replenishing the battery as it should? Voltage Regulator?
One thing at a time.

 

Leaking vacuum pressure?

Would cycling the convertible top have anything to do with the brake booster?

When something electrical is used, the ignition quits...

 

^^^

Leaking brake booster and car "tugging" at the lights.
Diminished brake, requiring excess foot pressure to hold after a few seconds.
That's what BQUICK was addressing.

 

Actually when I point to the battery in the above case, I would just start by removing and cleaning and remounting the cables. This seems more like a bad connection than a bad battery...

 

Sounds like your converter is too tight or as mentioned, booster leaking vacuum, or master with internal leak not holding pressure.