Is it electrical or gas?

Gary57210

Gary57210

Member
I'm having trouble with my 31. It will start but pretty quickly it will act like it's running out of gas. I've cleaned and checked the passages and jets in the carburetor (Zenith-2). I've set the float at 5/8".
I've changed distributors and coil. I'm running out of ideas, any suggestion?
 
rust in tank do you have a pencil filter in the shut off-on valve. remove line from carb and see if you have good flow when it happens?
 
How did you clean the carburetor ?
Where are the external adjustments set ? Have you tried changing them ?
 
How long is pretty quickly? What do you do or move after it starts, and is that when it sputters? Have you tried to see if your coil wire sparks next to the head after it dies?
If it does not, then squirt a short blast of ether in the carb and see if it briefly fires. You could just short across the points or if closed, flick them open with the ignition on instead of the coil wire thing. You should see a nice spark if the “electric” is working.
 
I blew through all the passages and replace all the gaskets. Set the float level to 5/8”. How long it runs varies from about30 seconds to a couple of minutes. I set the idle at approximately 1.5 turns. When it starts to die I,be tried choking it a little, but it still dies. I’ve checked for shorts on the primary wire and didn’t find any.
 
I gotta ask, is your gas cap vented and is the vent clear? Some caps with the single rivet in the center turn and cover the vent. I only use Eaton type gas caps.

With a plugged vent, gas will flow until it pulls a vacuum on the tank, stopping the flow.
 
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Have a can of starting fluid in your hand and give a quick spray into the carb throat just when it seems to want to die. If it catches and runs you will know it is wanting fuel. If it just dies it will be electrical.
 
If it is a spark issue it is easy to isolate. In the evening when it's not too bright of daylight lift all of the spark plug straps about 1/4" off of the top of the plugs. Start the engine and watch the spark, should be nice hot blue spark on all of the wires. You will be able to see if its steady or erratic.
 
x2 on the gas cap.


I watch the ammeter as my toe pushes the starter button. If I don’t see the ammeter twitch with each cylinder compression, I stop and install the safety fuse, open the fuel valve or turn the key on! This twitch is referred to as the ‘Henry Jiggle’. IMHO, ‘driver’ Model A’s should have the November 1929 Service Bulletin wiring change applied, so the primary ignition circuit function is reflected on the ammeter as a negative twitch at low rpms. If your car dies at speed out on the road, or when approaching a stop, before pushing in the clutch, check for Henry’s Jiggle. If the jiggle is there, the primary ignition circuit is likely working as it should. Check the secondary ignition circuit for consistent blue spark by removing the coil wire from the distributor cap, placing it close to a head nut / good ground and turning the motor over with the starter.

Your ammeter is your friend. If your car is wired correctly, you will see the ammeter twitch when turning the engine over with the starter, (key on). Immediately when the car dies, try to restart the car and watch for the twitch of the ammeter. If there, immediately follow up with the coil wire test. You can put the car in neutral, blocked wheels and standing next to the front fender, push the starter rod to engage the starter while watching the coil wire/head nut test. If good spark, probably fuel related, try the starting fluid with a spritz into the carb.
 
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Rob Doe said:
I watch the ammeter as my toe pushes the starter button. If I don’t see the ammeter twitch with each cylinder compression, I stop and install the safety fuse, open the fuel valve or turn the key on! This twitch is referred to as the ‘Henry Jiggle’. IMHO, ‘driver’ Model A’s should have the November 1929 Service Bulletin wiring change applied, so the primary ignition circuit function is reflected on the ammeter as a negative twitch at low rpms. If your car dies at speed out on the road, or when approaching a stop, before pushing in the clutch, check for Henry’s Jiggle. If the jiggle is there, the primary ignition circuit is likely working as it should. Check the secondary ignition circuit for consistent blue spark by removing the coil wire from the distributor cap, placing it close to a head nut / good ground and turning the motor over with the starter.
Click to expand...

I'll do that tomorrow, it's an easy one to do. Thanks
 
It is clearly running out of gasoline. Remove the drain plug (the one closest to the inlet) on the bottom of the carburetor and run the gas into a bucket. Should be a steady flow and continue until you turn off the gasoline. Just be careful. Do this outside and have a fire extinguisher handy.

This is a good site for the Zenith carburetor: https://model-a.org/default.html
 
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If gas flow it good and it idles good until it quits, I'd start looking at the condenser first. I always check easy things first. Condensers have always been one of the weakest components on the model A due to the heat the distributor is exposed to.

If the idle circuit is working with smooth idle then the only fuel related thing would be flow as already mentioned several times. If the fuel tank is producing corrosion particles and they can sometimes get past filtration (they are very fine particles) then filters or passages can get plugged but that is generally not a temporary thing. In other words, they don't unplug themselves. A fuel flow check will indicate that sort of a problem without much doubt.

An ignition coil can have temperature sensitive problems and it is usually a cracked or burned internal primary coil wire that opens as the coil warms up. Good coil testers give instructions to energize the coil for a while to warm it up. It doesn't take long for an electromagnet to get warmed up if it is energized. If a person inadvertently leaves the ignition switch on and the breaker points happen to be closed, it can fry the coil as well as drain the battery. To what extent of damage is an unknown. It may work for a while and then just quit until it cools back down. A good tester will check for this as well as spark efficiency.

A bad battery might have enough poop to get the engine to start but if the voltage is too low then the generator may not carry the load as it should. A bad battery is pretty obvious if it isn't performing well but a quick voltage check with a volt meter will confirm a sluggish battery.
 
When I was Technical Director for MAFCA a few years ago, I had a Member call me with this very problem. We checked to make sure the fuel valve was on (it was). He started it a couple of times so I could hear it on the phone. It was clearly running out of fuel. Opening the GAV did not help.

I asked him what his fuel level was (because low fuel level and a clogged up filter will not allow enough fuel to get to the carb). The guy was embarrassed... his gas tank was empty! He added 2 gallons from a gas can and the car started and ran just fine. :D

Just a reminder to start with the basics. These cars are quite simple in design.
 
Jim/GA said:
When I was Technical Director for MAFCA a few years ago, I had a Member call me with this very problem. We checked to make sure the fuel valve was on (it was). He started it a couple of times so I could hear it on the phone. It was clearly running out of fuel. Opening the GAV did not help.

I asked him what his fuel level was (because low fuel level and a clogged up filter will not allow enough fuel to get to the carb). The guy was embarrassed... his gas tank was empty! He added 2 gallons from a gas can and the car started and ran just fine. :D

Just a reminder to start with the basics. These cars are quite simple in design.
Click to expand...

Haha, love it!!
 
Well I borrowed another carburetor from a club member and the problem went away. So we're going to go back and double check my carburetor again.
Thanks again for all the helpful answers for my problem. When we find the source, I'll add it onto this post for future reference.
 
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