No spark to plugs happened overnight

[macbubba]

Howdy all ! All of a sudden I don't have spark at the plug on my 59AB?? Changed coil but don't want to keep buying parts to chase problem, Thanks for any help.

[Dick M]

First, I would check and see if you have power to the points using a test light. If you have power at the points, change the condenser. If that doesn't fix the problem, go to the next step.

The next step is to test the lead from the ignition switch to the distributor. If you find no power at the plug end of the lead from the ignition switch to the distributor, with the ignition switch on, using a test light check the ignition switch.

If you have power on the distributor side of the ignition switch with the switch on and no power at the plug, replace the lead from the ignition switch to the distributor.

If no power to the distributor lead side of the ignition switch when switch is on, replace the ignition switch.

Hope this helps you.

[Marshall V. Daut]

After checking Dick M's suggestions, try a different distributor cap, especially if you have a shiny repo cap. In the 1990's, inferior - but shiny! - plastic distributor caps were being sold that more often than not soon developed internal cracks that stopped spark from flowing to the spark plugs from the points. This happened especially in cold and/or wet, rainy weather. The moisture seeped into the cap and shorted out the flow of electricity, even though the cap looked brand-new. I got stranded for a couple days in a motel parking lot during a VERY wet cross-country Model A drive in the middle 1990's. Driving straight through in 30 hours, the engine had not been shut off since leaving Arizona (even while filling the gas tank) until it was finally parked in an Iowa City motel lot overnight. The next morning, the engine would not start. Exhausting my options for finding the source of the problem after two days, I borrowed an original crusty, filthy, disgusting-looking distributor cap from a Model A that had been sitting behind a garage for decades. The engine instantly fired up! Putting the new cap back on, nothing. It was a faulty cap that went bad overnight during rainy weather.
Since the weather in most of the country has gone cold and wet recently, your car might have one of these 1990's repo distributor caps that finally gave up the ghost. It's significant that the problem developed "overnight". That and the weather these days makes me suspect a bad distributor cap. Before panicking, put on a known good cap and see if that helps.
Marshall

[nkaminar]

Turn engine over until points are open. Turn on ignition. You should have battery voltage at the movable point. Now turn engine over until the points are closed. Turn ignition on again. You should have almost zero voltage at the movable point. If this checks out then you have a problem with the high voltage wiring. Check to see that the high tension lead is fully pushed into both the coil and the distributor cap. Do not leave the ignition on with the points closed for more than a couple minutes.

If no voltage at the movable point when open, then you have a problem in the low voltage wiring, which includes the ignition switch, any fuses, or wiring inside the distributor. Use your voltmeter to trace the voltage from the battery to the cable that screws into the distributor and any internal wires in the distributor.

If you buy parts to throw at it, then keep them as spares. Or borrow parts from friends to check if your parts are bad.


If the voltage at the movable point when closed then you points are not conducting and need cleaning or replacement.

Some other things to check: Check the condensor with an ohm meter. It should be low resistance when first connected changing to open circuit as it charges. Reverse the leads to re check. If anything else then the condensor is bad. Also check the distributor housing as discussed above. Also check the coil. But you said that you replaced the coil.

[Y-Blockhead]

Originally Posted by Marshall V. Daut

After checking Dick M's suggestions, try a different distributor cap, especially if you have a shiny repo cap. In the 1990's, inferior - but shiny! - plastic distributor caps were being sold that more often than not soon developed internal cracks that stopped spark from flowing to the spark plugs from the points. This happened especially in cold and/or wet, rainy weather. The moisture seeped into the cap and shorted out the flow of electricity, even though the cap looked brand-new. I got stranded for a couple days in a motel parking lot during a VERY wet cross-country Model A drive in the middle 1990's. Driving straight through in 30 hours, the engine had not been shut off since leaving Arizona (even while filling the gas tank) until it was finally parked in an Iowa City motel lot overnight. The next morning, the engine would not start. Exhausting my options for finding the source of the problem after two days, I borrowed an original crusty, filthy, disgusting-looking distributor cap from a Model A that had been sitting behind a garage for decades. The engine instantly fired up! Putting the new cap back on, nothing. It was a faulty cap that went bad overnight during rainy weather.
Since the weather in most of the country has gone cold and wet recently, your car might have one of these 1990's repo distributor caps that finally gave up the ghost. It's significant that the problem developed "overnight". That and the weather these days makes me suspect a bad distributor cap. Before panicking, put on a known good cap and see if that helps.
Marshall

Marshall, just so I am clear, are you referring to the cap

or the body?


I once had some Carbon tracking in my distributor body and there were sparks everywhere, mostly going to ground. We wiped out the moisture and she fired right up!!

[Marshall V. Daut]

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The body, your lower picture. That's what "distributes" the electricity to the plugs, firing order 1,2,4,3. #1 electrode is at the 4:00 position looking straight down into the body from the passenger's side, then the rotor moves counterclockwise through its rotation.
M.

[mcgarrett]

Originally Posted by macbubba

Howdy all ! All of a sudden I don't have spark at the plug on my 59AB?? Changed coil but don't want to keep buying parts to chase problem, Thanks for any help.

The OP says he's working on a 59AB. I assume he's working on a flathead V8?

[The Master Cylinder]

Originally Posted by mcgarrett

The OP says he's working on a 59AB. I assume he's working on a flathead V8?

Good catch.

[Marshall V. Daut]

Heck, I thought that "59AB" nomenclature was referring to some kind of AA Model heavy-duty truck body style that I'm not familiar with. ('Don't know squat about those animals!) Oh, well. Maybe the posted diagnostic suggestions will help some Model A owner with similar non-start problems.
Marshall

[old31]

Ohhhh, I did not pick up on the 59AB either. Anyways MAC you recived all good info for the fix.

[Planojc]

Originally Posted by mcgarrett

The OP says he's working on a 59AB. I assume he's working on a flathead V8?

When I first read the OP, my first thought was that he may have posted on the wrong forum.

[nkaminar]

The trouble shooting I posted in Post #4 applies to any car with traditional ignition system, including mechanical points.

[eagle]

If you want to really be stumped, keep throwing new parts at it until you have two or three problems instead of the original one problem. Or... buy a decent meter and print off a wiring diagram and learn how to troubleshoot. In the long run its the easy way.