Engine stalling when I put the lights on

[Randall Raines]

Hi fellows !

I've noticed a strange behavior of my '72 SSP. Yesterday night my engine stalled several times when I put the reverse gear. At the beginning I suspected the Reverse itself as D was properly working but today afternoon I made a trial and reverse was working properly, no stalling.

But when I turns the lights on I've noticed both R and D makes my engine stalling at idle. If I let it on P or N engine is idling properly (even 1 and 2).

This afternoon I tried to adjust the float of my carburator (Holley 4 bbl 3310-4). My level was a bit under the sight hole on both pumpers. But even I could not fix the issue.

I suspect my carburator setting, does anyone already had the same problem ?

 

[Beekeeper]

What are your RPMs at idle in park?

 

[Randall Raines]

I tried today I have 700 RPM in Park, but when I put the Drive I drop to 500 RPM and when I put lights on it drops dramatically to 0

 

[Beekeeper]

should idle in park at around 800 rpm

 

[Lionized]

I have a sneaking suspicion this is electrical and not fuel related. You may be running on just your battery and the power draw of your lights is enough to kill your spark.
Have your electrical/charging system checked first.

 

[dadsbee]

Running on his alternator... Load test the battery.

 

[Randall Raines]

You mean maybe my battery is not charged enough ? I have just put it out of the car today and put it in charge for the day. But seems reading you my alternator is not properly charging.... Strange coincidence zith my alternator belt that is making noise (squeaking)

 

[andyf]

Sounds like your engine isn't powerful enough to turn the alternator.

 

[Randall Raines]

that's why I thought about the carburator float not rich enough. Looking at it the level is not properly at hole sight. especially the secondary pumper. Yesterday I gave something like 20 360° turns on the screw counter clockwise to rise the float but still I doesn't see the level on the sight plug. Primary is instead quite good at level.

otherwise could be an idle issue, set too low when I turns lights on.

 

[62 Dart Convertible]

There sounds like something wrong with float level on secondary fuel bowl if you turn adjustment 20 turns and nothing happens. Luckily Holley so easy to remove bowl and check out float assembly/adjustment.

I agree with others sounds like your problem is electrical. Put a volt meter on ignition coil +ve while engine idling and see if it drops dramatically when lights on.
(Although, if battery was very weak, how would it even crank and start?!) Still, I'd eliminate electrical first...

 

[Randall Raines]

There sounds like something wrong with float level on secondary fuel bowl if you turn adjustment 20 turns and nothing happens. Luckily Holley so easy to remove bowl and check out float assembly/adjustment.

I agree with others sounds like your problem is electrical. Put a volt meter on ignition coil +ve while engine idling and see if it drops dramatically when lights on.
(Although, if battery was very weak, how would it even crank and start?!) Still, I'd eliminate electrical first...

Sorry guys I hadn't much time to put hands on my B body these last weeks but I did it today and I have checked some electrical stuffs.

First of all I put a Voltmeter on my coil and I read 5.2V when engine is shutted down. Then at idle I have still 5.2V but when I switch on lights level 1 (once pulled out) it drops to 4.8V then level 2 (twice pulled, full lights) I have the value that drops to 3.8V and engine stalls. I precise it stalls only in D or R, if I have 1, 2 or N and P it doesn't occurs.

I have noticed also when carb choke is pulled out at max (RPM at idle and Park around 2000) this issue doesn't occurs. It occurs when I decrease choke and RPM at idle is less than 1000, when Drive or Reverse is put and I switch on the lights.

My alternator belt makes some noise (squeak) maybe the issue is here...

By the way, the float issue is fixed, my needle was just blocked at bottom dead center and the nut wasn't on the seat of the needle anymore so it was turning empty. Now float level is properly set at the sight plug hole (maybe a bit rich but should be OK).

 

[62 Dart Convertible]

Sorry guys I hadn't much time to put hands on my B body these last weeks but I did it today and I have checked some electrical stuffs.

First of all I put a Voltmeter on my coil and I read 5.2V when engine is shutted down. Then at idle I have still 5.2V but when I switch on lights level 1 (once pulled out) it drops to 4.8V then level 2 (twice pulled, full lights) I have the value that drops to 3.8V and engine stalls. I precise it stalls only in D or R, if I have 1, 2 or N and P it doesn't occurs.

I have noticed also when carb choke is pulled out at max (RPM at idle and Park around 2000) this issue doesn't occurs. It occurs when I decrease choke and RPM at idle is less than 1000, when Drive or Reverse is put and I switch on the lights.

Glad you got your carb sorted, but clearly you still have an electrical problem.

As at idle you have such low voltage at coil, I'm surprised your engine even starts as battery voltage is at it's lowest then! (Though during cranking, your ignition switch bypasses the ballast resistor and puts full battery voltage on your coil to compensate.)

Maybe your ballast resistor or 12V supply to it has a problem/high resistance.

It is normal for your alternator to not produce much current at idle and thus only start to increase your battery voltage at fast idle and above. It is also normal for your coil voltage to be lower than battery voltage due to the ballast resistor in the ignition circuit - though your readings seem too low...

What I'd do is measure the voltage (with engine running on a fast idle) on the supply side of the ballast resistor. Should be close to same as battery voltage. If it isn't you'll be looking for why - like ignition circuit bad connection, bad ignition switch.
or
something else drawing big current and pulling voltage down.

 

[Randall Raines]

I will start by changing my alternator belt, because I have noticed it is slipping on the alternator pulley this might affect the power of my alternator. I have a 6226 MC gates belt but I have heard Conti belt are better; someone knows about the conti belt model I should take ?

 

[biomedtechguy]

When my alternator went out, the last mile I had to limp back, and the last half mile I had to turn the headlights OUT, or the engine wouldn't run. It never killed, fortunately, but it was running on battery only, so that seems to be your problem.

 

[theamcguy]

This was a common problem back in the day. Your idle speed is too low. Start car set hot idle to specs in Park, put car in drive, adjust idle with headlights to whatever it was in drive with no headlights on, problem solved. You will notice that in drive with no headlights your idle speed will be higher but that's just the way it is. When your alternator is charging and it puts a drag on the engine and that brings the idle speed down. It is a balancing act to get the idle in Park, Drive and Drive with alternator all balanced out so that the idle in drive no headlights is not excessive. I seem to remember that some TSMs recommended setting the idle in drive with headlight and heater fan blowing on high.