Unfixable random cutting out

[Chris Van]

Hi Boffins

I have a problem that is unfixable but thought as a last resort to post the symptoms here and see if anyone in the World can figure out what is going on although I have basically given up.

My 31 Town Sedan (still 6 volts) cuts out randomly. It starts with a warning misfire... then shortly thereafter cuts out completely as though you have turned off the ignition switch. Then you let it stand/cool down for 5 minutes then it starts again like nothing ever happened and pulls like a train. I have been driving the car daily for 15 years with never a glitch. And now this.

I have tried the following, to no avail.

1. Replaced the coil with a proven working used coil.
2. Replaced the condenser (three times with three working ones, just in case)
3. Drained the tank and refilled with fresh petrol.
4. Washed out the fuel tap, but the gauze filter was still clean as a whistle.
5. Tried driving with no fuel cap in case it was causing an air lock.
6. Replaced the points with brand new ones and set them properly and check there are no loose wires etc.
7. Bridged the ignition switch.
8. Replaced the rotor.
9. Replaced the top of the distributor cap.
10. Cleaned out the carburetor (multiple times).
11. Installed a glass bowl fuel filter as a water trap. No water in the fuel.
13. Checked that all the jets are clean and tight.
14. Checked that the ammeter wires are tight.

If anyone can shed any light on this mystery I would be very grateful as it is driving me crazy. It is very dangerous to have a car that cuts out at random but it is my daily driver so I don't have a choice. And nobody can fix it.

Thanks guys.

Chris Van
Johannesburg, South Africa

[J Franklin]

It is important to determine if it is fuel or electrical when it cuts out. Carr a can of starting fluid to check for a fuel problem and check for spark at the spark plugs for an electrical problem.
Good Luck!

[Dave in MN]

It sure acts like a failing coil. Fails when heated.

I would try cleaning all the wire connections in the junction box and under the dash panel. Little bit of emery cloth to make them shiny. Put it all back together and snug down the bolts/nuts tying it all together.
Good luck with it.

[jb-ob]

2X Dave. Do a complete 'tight & bright' secession on all connections.


My case, battery cable at starter switch wasn't tight.


Good Luck, JB

[JayGriff]

How hot does it get there? Do you use ethanol gas? I've read where the gas in the carb bowl can start to boil and cause similar symptoms in hot climates or when the engine is running hotter than it should for some reason. Some say using non-ethanol gas helps.

[john charlton]

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The warning misfire could indicate fuel starvation maybe the float hung up or sticky float valve or an errant bit of teflon tape in the works . The carb is the only part of the car which is actually alive and has a mind of its own . I have had this trouble and put another carb on and cured it . Took the original carb apart and could find nothing at all wrong ,correct float height ,clean correct jets etc etc . One day I am going to catch it by surprise and bolt it on to see if it has forgotten why it was p*ssed off with me !!!

John in sunny day but not quite like Camps Bay in even more sunny SA (after school worked at Mr de Beers garage for pocket money) Suffolk County England .

[WHN]

I agree with checking and cleaning every wire connection on your car.

But! I do believe it’s the carburetor or other gas line issue. I had a similar problem many years ago. Replaced a rebuilt Zenith with a (new) Zenith, problem went away. Has never come back.

Check your plugs to see how they look. Have you recently changed them?

[Growley bear]

Did it start cutting out and stalling out of the blue, or was something repaired and then it started the problem?
I was looking for this same thing and fount the main harness wire at the starter connection loose. Nut was tight and the solder joint "LOOKED" great. I touched the wire lightly and the engine quit. Some problems are not real obvious. I would start by gently pushing/pulling on all connections as there might be a loose one. Check that when the engine quits that if no voltage to ignition, does the rest of the system still have voltage. Also remember that even if there is voltage across a connection it still may not carry the correct load without breaking down.
Any time an electrical problem is suspected, the battery should be thoroughly checked for voltage, cell specific gravity and a load test first before proceeding.

[gweilbaker]

Check the junction box terminals between the box and the firewall, the repros would easily short due the heads protruding beyond the box although with the age of your A it sounds like you have an original, but it's something to check.

[Tom Endy]

Loose connection or corroded connection on the two wires to your ammeter could be a problem.


Same if any of the connections on the terminal block on the firewall are loose or corroded.


As someone suggested clean and tighten all your electrical connections.


Here is where it is prudent to carry a spare distributor in your car that has the points properly set and has been timed for your car and run a short distance for a road test. It is then ready to drop in the engine without having to set the points or the timing as long as you do not loosen the cam screw.


The next thing to have is a by-pass cable that connects to the distributor and clips to the low side of the coil. Most of the Model A suppliers have them.


The third thing to carry is a trouble light. They work on both 12-volt and 6-volt. It is shaped like a screwdriver with a single lead with a clip-lead attached, and a light in the handle. At the first signs of trouble use the light to check all the areas that should have voltage. If voltage is present the light will light. Most auto parts stores have them.


A known good distributor and a by-pass cable installed will eliminate a number of unseen, inaccessible trouble areas where you are likely to lose voltage to the ignition points. The trouble light will tell you if you need to go this route.


Tom Endy

[rocket1]

I would try another ammeter.

[George Miller]

Is your armored cable screwed in to far or not far enough. Sound electrical to me. when the connection gets warm it loose connection, but it is hard to say with out checking it in person.

[canadian]

heres the thing, don't jump all over the car wondering in awe whats happened , you said two things in your post .. first a misfire was detected.. two it starts after five minutes of sitting. so you have five minutes to do to tests.. as a previous poster said .. spray starting fluid in carb while a helper cranks engine it should fart burp backfire spit hiccup or puke meaning you have ignition trying to fire whatever the engine is trying to injest. if no response or indication of attempting to start then you have a electrical issue...K.I.S.S. keep it simple stupid. please post your findings they educate us all.

[AL in NY]

Sounds like an electrical problem to me. First thing I'd check is the electrical resistance from the distributor points plate to battery ground. Should be 1 ohm or less. If that checks out good, I'd run a wire from the battery ground to the distributor points plate and and run the car with that wire in place to see if your problem goes away. It maybe an intermittent open or high resistance gound somewhere between the battery and the distributor.

[barnstuf]

I also suspect electrical. A starting point I have used with good results is running the car in total darkness with the hood open. You may spot the problem in the dark.

[Bulligen]

Ignition wire grounding out at the back of the switch against the gas tank?

[jrelliott]

What type of ignition switch do you have? Original ones usually do not have problems, but the replacement ones did have problems. The other suggestions are good, but look to see if fuel or electrical as mentioned before. Problem sounds electrical

[Mark DeRoseau]

Pencil filter in tank.

[SSsssteamer]

Originally Posted by dave in mn

it sure acts like a failing coil. Fails when heated.

I would try cleaning all the wire connections in the junction box and under the dash panel. Little bit of emery cloth to make them shiny. Put it all back together and snug down the bolts/nuts tying it all together.
Good luck with it.

x 3

[pooch]

Easy way to check if spark is the culprit.

Plug a timing (strobe ) light into the coil lead and hang in thru and tape to dash.

Go for a drive.

Observe how the light acts when it begins to shit itself.