Vapor Lock

Sounds like the gas cap is not venting . Had the same problem as you and turned out to the gas cap was not venting .
 
Tiny said:
New gas cap from Bert's. So I doubt it
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New repro 30-31 gas caps are notorious for not venting properly. Do not assume that new means good. Run a test with the gas cap loose to rule out a problem with the cap vent.
 
do you see gas dripping or smell gas when this happens ? next time you stop shut off the gas and see if their is any change, rule out one thing before going to the next
me thinks a new A&l condenser is in your future
 
this happened to me. I found that opening the carb rich a 3/4 turn gave greater gas flow for a short time solved the problem soon you can return to usual adjustment
 
I also have a continuing problem with what I believe is vapour lock. When the fuel level reaches 40mm and Ive run the car hot, m/way or hill climb, then just after ive dropped the speed she stops dead. Put a gallon of fuel in it and away she goes. Its happened 4 times, twice in exactly the same circumstances. Has to be vapour lock, tank is perfect. Maybe not enough head of pressure to push the air through???
 
I know most people say model a's don't get vapor lock but when I stop for gas on a hot day it is not unusual to be hard to start and runs rough for the first minute or so. I think todays gas has a lot to do with it.
 
Update time!!!
I spent the day in the workshop. I'm almost embarrassed to report my findings.
I started with the ignition system.
The points were a little tight.
The timing had moved just a hair.
I checked the clearances in the body at the 4 lugs. They were at .004, .006, .014 and .016. They are all now .025.
I also replaced the condenser for good measure

I took it for a test spin at this point and it was better but not right.

Upon returning home it was peeing fuel out of the carb.
I took the carb off and apart thinking stuck float. When i disconnected the fuel line nothing drained out. The tank valve was shut after the motor had been shut down. I cleaned and blew out all the passages. Then regasketed the carb with new and reinstalled it.

It started right up and ran great. I let it warm up and went for a test spin. After about a 5 mile drive I stopped at a buddies to shoot the breeze. After 10 minutes it was test time. She fired right up and drove home without any issues.

My final diagnosis
I don't believe it was a true vapor lock.
What I had was " the Death of a Thousand Cuts" or a lot of little issues becoming a big problem.

Thank you everyone who offered advice.
I love this place:)
 
I am glad it is fixed but I have no idea what the problem was.

Vapor lock is a very real issue but prolly not what you were experiencing, esp at cooler temps.
Wonder if your gas line was too far into the carb, touching the back wall and cutting off fuel flow. This could have been corrected when you removed the carb.

I have experienced vapor lock on cars since the '60s, many diff. kinds of cars, incl. Model As. Once you have had it happen it is unmistakeable. It is the only self-correcting problem I am aware of.

I was also gonna suggest changing the condenser/ or coil; they can be sensitive to heat
 
I run MMO in every tank of fuel and in every oil change. Love that stuff!!
Went for a spin today. Issues still appear to be solved. I'm trying to make it on my first club tour in about a week so I want it running tops. Nothing like the new punk kid showing up for his first tour and breaking down. I don't wish to be that guy:)
 
Just got to read this post.
Does the fuel line have correct pitch ?
Some fellas have brought up the theory of an improper ground and that the fuel line may be acting as a ground causing the line to get hot/warm.
 
Tiny - In your post #29, you mention the clearances between the distributor body contacts and the rotor contact was from .004" - .016". This discrepancy just might have been your main problem. (Speculation on my part only.)

This item is very often over looked, but is just as important as the gap at the sparkplugs.

Glad you got it running.
 
Quit screwin around and remove the gas cap. It sounds like the vent is full of rust. Just enough venting to let it idle until the second coming of you know who but when under load it runs out of venting air. Try blowing the rust out of the caps...it may help. Been there and it drove me nuts. Next time it happens, immediately and SLOWLY remove the gas cap. If you hear a swwoosh of rushing air that's it.
 
Bob
Its not the gas cap. Never has been. That's an easy fix. Read response #29. It was much more than a simple clogged vent:)
 
:DLOL Glad the problem is solved. I was speaking from personal experience and it was trial and error for me. Part of the problem in my case was two fold as I was running a micro filter and a pencil filter. The micro filter collapsed after being freshly installed and the I discovered my gas cap full of rust and swoooosh when I unscrewed it. New gas cap and no micro filter.....life has been good for 10 years. Whiskey for me and fresh horses for my men!
 
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