CAR STALLS WHILE DRIVING!!!

[xpxgizmo]

Hello, 

I am a proud new owner of a 1972 Datsun 240z. I have owned the vehicle for about 3 months now. I am fairly new to cars so my knowledge and experience is limited. 

I have been having an issue where the car will stall while driving, as if someone turned off the ignition and no throttle response. All the lights and electronics work. I try turning it back on but it will just crank. Maybe after 5-10 minutes, it will start back up and run smooth. When running, it is really smooth and responds very well. 

I don't think it's a fuel related issue. The lines are not clogged and last time it stalled, I had fuel in the bowls. I also checked the ignition coil and all the spark plugs and they get spark when the car is running. 

- Electronic fuel pump installed (removed oem mechanical fuel pump) 
- MSD 6A Ignition Box
- Mallory Unilite Distributor 
- MSD Blaster 2 Ignition Coil (just put in recently)
- New spark plugs
- New battery

I have attached photos of my engine bay. I have also attached videos of the car running. 

It is such an unsettling feeling and now I am too afraid to drive it. Any help would be appreciated! 
 

IMG_3517.MOVIMG_3518.MOVIMG_3519.MOV

Edited February 3, 2023 by xpxgizmo
added photos

[Zed Head]

It's probably the Unilite or the MSD box.  Both electronic.  One easy thing that you could do is to disconnect the MSD and just run the Unilite.  If the problem still happens it might be the Unilite.  The Unilite should have its own ignition module.

Also, if you do take it out again watch the tachometer needle immediately after the problem happens.  I assume that it is manual transmission.  Hopefully there is room on the road to leave the car in gear so that the engine continues to turn.  If the engine is turning but the tach needle is not moving then you have a spark problem.

Apparently Pertronix bought Mallory.  Can you take a picture of what's under the distributor cap?  Not clear what exactly you have.

https://pertronixbrands.com/products/pertronix-ml-182-ignitor-mallory-unilite-8-cyl

[SteveJ]

18 minutes ago, xpxgizmo said:

Hello, 

I am a proud new owner of a 1972 Datsun 240z. I have owned the vehicle for about 3 months now. I am fairly new to cars so my knowledge and experience is limited. 

I have been having an issue where the car will stall while driving, as if someone turned off the ignition and no throttle response. All the lights and electronics work. I try turning it back on but it will just crank. Maybe after 5-10 minutes, it will start back up and run smooth. When running, it is really smooth and responds very well. 

I don't think it's a fuel related issue. The lines are not clogged and last time it stalled, I had fuel in the bowls. I also checked the ignition coil and all the spark plugs and they get spark when the car is running. 

- Electronic fuel pump installed (removed oem mechanical fuel pump) 
- MSD 6A Ignition Box
- Mallory Unilite Distributor 
- MSD Blaster 2 Ignition Coil (just put in recently)
- New spark plugs
- New battery

I have attached photos of my engine bay. I have also attached videos of the car running. 

It is such an unsettling feeling and now I am too afraid to drive it. Any help would be appreciated! 

Immediate cut-off implies electrical.  How long are you driving before it happens? Are there any symptoms prior to cutting out, such as the tach needle dancing or the car bucking?

How old is the MSD? Have you tried seeing if it's hot when the car shuts down? Is the coil getting hot? (New doesn't always mean good.)

You could always tried the canned air trick. Keep a can of dusting air in your car. When it cuts out, hold the can of dusting air upside down and spray the MSD. If the car restarts sooner, then the MSD could be failing. Same thing for the coil.

[xpxgizmo]

18 minutes ago, Zed Head said:

It's probably the Unilite or the MSD box.  Both electronic.  One easy thing that you could do is to disconnect the MSD and just run the Unilite.  If the problem still happens it might be the Unilite.  The Unilite should have its own ignition module.

Also, if you do take it out again watch the tachometer needle immediately after the problem happens.  I assume that it is manual transmission.  Hopefully there is room on the road to leave the car in gear so that the engine continues to turn.  If the engine is turning but the tach needle is not moving then you have a spark problem.

Apparently Pertronix bought Mallory.  Can you take a picture of what's under the distributor cap?  Not clear what exactly you have.

https://pertronixbrands.com/products/pertronix-ml-182-ignitor-mallory-unilite-8-cyl

Hello and thank you for your response and useful information. 

When the car stalls, I can confirm that it is in gear. The tach drops to zero and doesn't move. No throttle response while in gear too. So it's a spark problem? 

I attached photos with the dist. cap off. Would the pertronix ignition module work with my distributor? 

                         

[xpxgizmo]

25 minutes ago, SteveJ said:

Immediate cut-off implies electrical.  How long are you driving before it happens? Are there any symptoms prior to cutting out, such as the tach needle dancing or the car bucking?

How old is the MSD? Have you tried seeing if it's hot when the car shuts down? Is the coil getting hot? (New doesn't always mean good.)

You could always tried the canned air trick. Keep a can of dusting air in your car. When it cuts out, hold the can of dusting air upside down and spray the MSD. If the car restarts sooner, then the MSD could be failing. Same thing for the coil.

It's really random. I drove it for 45 minutes on the freeway and it didn't shut off. No symptoms at all. The MSD came with the car when I purchased and the previous owner doesn't know. I will check next time to see if the MSD and coil is hot after car shuts off and try the canned air trick. Thank you! 

[SteveJ]

If the freeway traffic is moving (Does that happen in LA any more?), there might be enough air moving through to slow the heat build up, provided that is the cause of your dilemma. Heat is an enemy of electronics. If the car is cutting out sooner in stop and go traffic, that's an additional sign that it's heat related.

[xpxgizmo]

1 minute ago, SteveJ said:

If the freeway traffic is moving (Does that happen in LA any more?), there might be enough air moving through to slow the heat build up, provided that is the cause of your dilemma. Heat is an enemy of electronics. If the car is cutting out sooner in stop and go traffic, that's an additional sign that it's heat related.

that makes sense... but the car stalled several times winter nights where the temperature was 45 degrees. It does seem to happen on surface streets with stop and go traffic. 

[Zed Head]

That's an old original Mallory Unilite.  I don't know much about them, except that I think that Mallory sold a complete distributor but might also have sold a conversion kit.  I think that you have the original light triggered Unilite.  The black disc on top has a vane that breaks the light beam.  I think that Pertronix might have converted the "light" trigger (hence Unilite) to magnetic.  

Here's an old thing I found.

https://www.zhome.com/ZCMnL/tech/MalloryDist.htm

Since you're in there you might as well check your mechanical and vacuum advance mechanisms.  See what shape the distributor is in before deciding how to fix it.

Edited February 3, 2023 by Zed Head
text turned red for some reason...

[xpxgizmo]

1 minute ago, Zed Head said:

That's an old original Mallory Unilite.  I don't know much about them, except that I think that Mallory sold a complete distributor but might also have sold a conversion kit.  I think that you have the original light triggered Unilite.  The black disc on top has a vane that breaks the light beam.  I think that Pertronix might have converted the "light" trigger (hence Unilite) to magnetic.

Here's an old thing I found.

https://www.zhome.com/ZCMnL/tech/MalloryDist.htm

Since you're in there you might as well check your mechanical and vacuum advance mechanisms.  See what shape the distributor is in before deciding how to fix it.

Thank you for the link. I will check it out. As for as bypassing the MSD, is that simple to do? 

[Zed Head]

The heat comes from the electrical current.  It might be worthwhile to disconnect all of the connections and clean then up then see what happens.  Bad connections can cause heat, and they can also open up after they get hot.  It might not be one of the two ignition modules.

Then you'll know exactly what you have and what state the parts are in.

[xpxgizmo]

46 minutes ago, Zed Head said:

The heat comes from the electrical current.  It might be worthwhile to disconnect all of the connections and clean then up then see what happens.  Bad connections can cause heat, and they can also open up after they get hot.  It might not be one of the two ignition modules.

Then you'll know exactly what you have and what state the parts are in.

ok thank you! So just to clarify, I should clean all ignition related electrical connections? The ignition switch as well? As you can tell, I am very much new to this. 

[Zed Head]

I would just focus on the MSD and the Mallory parts and the coil to start.  Look for signs of overheating, clean things up, assess the quality of the parts.  Be careful moving things around the Mallory module might be adjustable.

p.s. I didn't really study your pictures before.  Looks like you have the full Mallory distributor.  Not sure if you can get replacement parts for those.

Edited February 3, 2023 by Zed Head