Car died while driving now won’t start

[Pescado]

Just adding in....prior to this breakdown car was running great

[TX82FIAT]

Glad you were able to get the car started. A stumble at 2800 RPM's feels like an air, fuel mixture issue.

[18Fiatsandcounting]

Pescado, since the idle is good, I doubt you have an air leak in the intake manifold area. As TX82Fiat suggested, it could be a fuel issue like you're not getting enough fuel. It could also be an ignition timing issue, although I'd have to know more before I can offer any more.

Since the car idles, try this: Get the car warmed up at idle, then slowly work the throttle by hand as you peer over the engine and listen to it. Very slowly increase the rpm. Does it start to stumble only at 2800 rpm or so? Can you get it past 2800 rpm and then everything is good once you get beyond that? And I forget, but has this carburetor been rebuilt (other than the new accelerator pump spring)?

I'd also attach a timing light to the central plug wire (the one from the coil to the distributor). Watch the flashes as you try to rev the engine, and see if the flashes drop out at any point as you try to slowly increase the engine speed from idle to 4000 rpm or so. It should be almost a continuous stream of light, so "skips" are easy to see.

-Bryan

[Nut124]

Ok so got the new diaphragm in with homemade spring and solved the fuel leaking issue so that's good...but sadly

-current problem...at around 2800rpm car sputters but doesn't stall, when I'm off the accelerator good idle

Does it sputter at 2800 while driving or when stationary?

[Pescado]

Ok so got the new diaphragm in with homemade spring and solved the fuel leaking issue so that's good...but sadly

-current problem...at around 2800rpm car sputters but doesn't stall, when I'm off the accelerator good idle

Does it sputter at 2800 while driving or when stationary?

Not sure if it currently does it at 2800 when driving…I would need to take it out again. I’ll try and report back.

[Pescado]

Pescado, since the idle is good, I doubt you have an air leak in the intake manifold area. As TX82Fiat suggested, it could be a fuel issue like you're not getting enough fuel. It could also be an ignition timing issue, although I'd have to know more before I can offer any more.

Since the car idles, try this: Get the car warmed up at idle, then slowly work the throttle by hand as you peer over the engine and listen to it. Very slowly increase the rpm. Does it start to stumble only at 2800 rpm or so? Can you get it past 2800 rpm and then everything is good once you get beyond that? And I forget, but has this carburetor been rebuilt (other than the new accelerator pump spring)?

I'd also attach a timing light to the central plug wire (the one from the coil to the distributor). Watch the flashes as you try to rev the engine, and see if the flashes drop out at any point as you try to slowly increase the engine speed from idle to 4000 rpm or so. It should be almost a continuous stream of light, so "skips" are easy to see.



-Bryan

I’ll need to find a timing light first…let me know what other info I should gather to help out.

[Pescado]

Thanks for the help guys.

[Pescado]

Is it possible that the replacement of the magnetic pick up module or ignition module could be causing this? Maybe I did something wrong? Could starting the car with a broken magnetic pick coil throw the timing off? Just trying to rule out the current repairs here.

[18Fiatsandcounting]

Is it possible that the replacement of the magnetic pick up module or ignition module could be causing this?

I'm not an expert on electronic ignitions, but yes, I believe it could. The issue is the clearance between the "lobes" on the rotor and the magnetic pickup. There is a spec for this, but there also appear to be some shop manuals that have the wrong clearance. Perhaps someone reading this knows what the clearance should be.

If the clearance were wrong (most likely too large), you might see erratic "triggering" at certain rpms. I can't guarantee this is your issue, but it's worth checking out. And, if you do find a timing light, the lack of flashing at certain rpms would be a pretty strong indicator that you're not getting a good spark all across the entire rpm range.

-Bryan

[18Fiatsandcounting]

PS: I looked it up, and the correct air gap between the rotor and the magnetic pickup should be 0.020" to 0.024", or 0.5mm to 0.6mm. In some manuals it's listed as less than this. This is for the stock distributor, and aftermarket units might be different.

Some people prefer to use plastic or brass feeler gauges to set the gap, because they are not magnetic. Honestly though, I think the regular old steel feeler gauges should work. The old school trick is the thickness of the cover on a book of matches, but this is a little bit on the low side, being more like 0.016". Still, if you set the gap to be slightly loose using the match book trick, you're probably going to be close to 0.020".

-Bryan

[spider2081]

I'm no expert with these distributors but some of my observations are:

The screws that hold the pick up coil plate to the distributor plate are a critical length. If too long a screw is used the screw can bind the vacuum advance and make it inoperable.

The distributors lobes can be damaged if they strike the pick up coil. A visual inspection of each of the 4 lobes as they pass the pick up coil bar is important. Each lobe should be square to the pick up coil bar and have no signs of scraping on its surface.

Movement of the vacuum advance rod should be observable when the engine is accelerated
I have seen many distributors with excessive gaps appear to operate just fine. I'm inclined to think the gap is not super critical. It is important that the 4 lobes do not touch the pick up coil as the shaft rotates.
Some pick up col base plates are too large and when properly gaped the side of the plate prevents the distributor cap from properly sitting on the distributor housing.
The magnet orientation to the pick up coil base plate is important. Many people mention a white line of the magnet. I think the pick up coil base and the magnet have a unique shape. This shape only aligns one way. In other words the base and the magnet are not a symmetrical shape. The only match when assembled one way.

[Pescado]

I'm no expert with these distributors but some of my observations are:

The screws that hold the pick up coil plate to the distributor plate are a critical length. If too long a screw is used the screw can bind the vacuum advance and make it inoperable.

The distributors lobes can be damaged if they strike the pick up coil. A visual inspection of each of the 4 lobes as they pass the pick up coil bar is important. Each lobe should be square to the pick up coil bar and have no signs of scraping on its surface.

Movement of the vacuum advance rod should be observable when the engine is accelerated
I have seen many distributors with excessive gaps appear to operate just fine. I'm inclined to think the gap is not super critical. It is important that the 4 lobes do not touch the pick up coil as the shaft rotates.
Some pick up col base plates are too large and when properly gaped the side of the plate prevents the distributor cap from properly sitting on the distributor housing.
The magnet orientation to the pick up coil base plate is important. Many people mention a white line of the magnet. I think the pick up coil base and the magnet have a unique shape. This shape only aligns one way. In other words the base and the magnet are not a symmetrical shape. The only match when assembled one way.

Thanks for helping out….should one of the four lobes be lined up perfectly with the magnetic pick up coil when the car is off? Currently when the car is stopped/off the magnetic coil is in between lobes.

[18Fiatsandcounting]

should one of the four lobes be lined up perfectly with the magnetic pick up coil when the car is off?

Not necessarily. The lobe orientations will depend on when the engine stops turning when you turn it off. That can be pretty much anywhere, including perfectly lined up with the pickup but that would just be coincidence.

-Bryan

[Pescado]

should one of the four lobes be lined up perfectly with the magnetic pick up coil when the car is off?

Not necessarily. The lobe orientations will depend on when the engine stops turning when you turn it off. That can be pretty much anywhere, including perfectly lined up with the pickup but that would just be coincidence.

-Bryan

Ok…you mentioned earlier a “match book “ measurement….is this the gap between the lobe and the magnetic pick up coil?

[spider2081]

should one of the four lobes be lined up perfectly with the magnetic pick up coil when the car is off?

My thought on this is, Look at the shape of the lobes and the space between them. The odds are when the engine stops rotating the peak of any lobe will not be aligned with the pick up coil bar. It will almost always stop between the high points or peaks of the lobes.