Vapor lock

mshmodela said:
In my newbie opinion if corn base fuel sits in a hot carburetor (after a drive) the fuel may turn to vapor more easier than 100 gasoline. I think though with cool fuel from the cowl tank flowing in the the bowl that's not likely to happen... But once you turn the car off and let it sit... you might in theory experience this... Tests and experiments could likely proves this once and for all... I might take a carburetor with a small port-hole on the side of the bowl and a camera to really prove or disprove...
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When I was new to my Model A I would shut off the fuel while I went into a store (or where ever) and when I went to restart it would back fire and run terrible until I let it set awhile.

When I started NOT shutting off the fuel it did not act up. I can only assume that with the fuel shut off the gas in the carb got hot. Leaving the fuel turned on may have had a cooling affect.

I can think of no other reason for this phenomenon. :eek: :eek:

So now I just leave the fuel turned on all the time except when parked overnight.


Big hammer said:
because of the nitrogen enriched fuels today!
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I have never heard of "nitrogen enriched fuels". What would be the purpose of that. N2 doesn't burn and is lighter than air so it would just evaporate.
 
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It happened to us on a long tour. We pulled a long 6 mile gentle climb, temperature 100+, elevation 2000'. Mostly high gear but some second.

About 5 miles in to it, she shut down. Slapped some ice on the carb. and we up and going in 10 minutes we were up and going.

Made the rest of the climb with the hood halves propped open, and in second gear.
 
She'll oil at their pumps has some wording of nitrogen enriched fuel
I thought nitrogen as a gas, and would dissipate and had a good laugh!
I just pump it then go drive :-)
 
I've asked this before, but never got an answer or even a comment: why is that many of us who live in California, and can buy only "crap gas" with corn in it, drive on hot summer days, and never experience vapor lock? If the gas were the main problem, then we would see far more cases of vapor lock in all those states that do not have fuel choices.....thoughts????? And I don't like crap gas....My main problem with it is my mileage surely suffers some....
 
TerryH said:
I've asked this before, but never got an answer or even a comment: why is that many of us who live in California, and can buy only "crap gas" with corn in it, drive on hot summer days, and never experience vapor lock? If the gas were the main problem, then we would see far more cases of vapor lock in all those states that do not have fuel choices.....thoughts????? And I don't like crap gas....My main problem with it is my mileage surely suffers some....
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I'll give you my opinion, ....there are WAY more folks out there who drive their Model-As on tours (-with the same gasoline) with frequency that never experience any type of "vapor lock" issue. Therefore how can they write about vapor lock? :confused:

Now the one thing I have noticed many times is that modern fuels go stale within a short period of time. Even 60 day old fuel will create driveability issues. Is it vapor lock? No, but folks gotta blame it on something. Ironically, how poor do we think the fuels were back in the depression era? Did the Model-A run on it then?? ;)
 
forever4 said:
Why does this thread start with post # 2?
What happened to post # 1?
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I see all the numbers OK on this thread, but for the past few months my computer has had a problem with the numbers on many posts. It might show 20 posts, but lists a page 2, which isn't right because page 2 should have post #21. If I click on page 2 it just takes me back to the top of page one with post #1.

I thought it was just my computer that was vapor locked.
 
BRENT in 10-uh-C said:
I'll give you my opinion, ....there are WAY more folks out there who drive their Model-As on tours (-with the same gasoline) with frequency that never experience any type of "vapor lock" issue. Therefore how can they write about vapor lock? :confused:

Now the one thing I have noticed many times is that modern fuels go stale within a short period of time. Even 60 day old fuel will create driveability issues. Is it vapor lock? No, but folks gotta blame it on something. Ironically, how poor do we think the fuels were back in the depression era? Did the Model-A run on it then?? ;)
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As usual, Brent has got it right. I just poured off 5 gallons of corn gas that had sat in my sedan for two months. The car, which normally performs beautifully, would barely start, then not run at all. I felt like I'd whipped a puppy. I put two gallons of real gas in and we're back to normal.

In 55 years of driving a Model A in all kinds of conditions I have never experienced anything like vapor lock. There have been high altitude effects, and loose wires, and overheating, but nothing I would call vapor lock. Just one man's experiences.
 
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I leave 10% gas in my vehicles all winter and have never had a problem starting or running. In my 8N it sometimes sets for a year and again it has no problem starting or running.
 
ed thibodeau said:
I leave 10% gas in my vehicles all winter and have never had a problem starting or running. In my 8N it sometimes sets for a year and again it has no problem starting or running.
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Oregon is notorious for high priced poor quality gas. Plus, we had something like 120% humidity and record rainfall from Nov. 1 - Dec. 31.
 
There was a great article in Hemming's Classic Car about a year ago. When I find it, I'll post. Have fun with the popcorn...
 
With regard to the "vapor lock never happened to me, so it can't be true..."

My Model A has always started, so anyone that hasn't been able to start their car must not have a problem...eh?

Marc
 
Y-Blockhead said:
When I was new to my Model A I would shut off the fuel while I went into a store (or where ever) and when I went to restart it would back fire and run terrible until I let it set awhile.

When I started NOT shutting off the fuel it did not act up. I can only assume that with the fuel shut off the gas in the carb got hot. Leaving the fuel turned on may have had a cooling affect.

I can think of no other reason for this phenomenon. :eek: :eek:

So now I just leave the fuel turned on all the time except when parked overnight.


Makes sense... In fact it might be actually safer... I happen to have flown on TWA 800/803 in 1995 about a year before that accident and that was a hot fuel vapor explosion... Keeping fuel in liquid form as opposed to vapor is saver during storage...
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I used to have a vapor lock problem with my 49 Ford V-8. It has the fuel pump on top
of the motor and on a hot day pulling a steep long grade it would act up. I got to carrying
a cooler with ice in it. I would get out and dump ice on the fuel pump and she would start
right up again and run the rest of the way up the grade. I think it was vapor lock.
I had another problem with the crap gas here in California a few years back when they
must have changed the gas forumla. I have a 1915 Model T which is hand cranked.
I have been cranking this car for 50yrs. so very familar with it.
I had filled the tank and parked the car. A week later I took the car out for a drive. It
started just like always when it was cold in the garage. One pull with the choke on and
one or two cranks and started right up. I went to the hardware store about a 10min. drive and went in a did some shopping. I was gone about 15-20 mins. and came out
to start the car. Usually it starts on one crank with no choke under this condition but
this time I cranked and cranked. I choked it a couple of times and nothing. I thought maybe I had flooded it so I pulled a plug, it was dry as a bone.
I went to the burger joint next door and got a cup of ice, threw it on the manifold and
it started right up. This happened a couple of more times after this so I called the tech
line for Arco gas. The tech told me they had indeed changed the formula and some older
cars had to crank a little longer as the fuel was evaperating in the hot intake manifold
before it could get to the cylinders. When I explained that I was the cranker and how
dagerous it would be I it happened in the middle of an intersection, he suggested I
put the mid range gas in it as it wouldn't evaperate as quickly as the cheap gas.
I did this and haven't had a problem since.
 
The Flathead V-8's are especially bad about vapor lock with todays "Corn Gas". We have found adding a little Diesel fuel in the gas usually solves the problem. Real gasoline from the "old days" had a higher vapor pressure than todays blended fuels. Add about a pint for every 10 Gals of gasoline. The diesel will raise the vapor pressure or boiling point of the gasoline.

I know there are some who will say that this is not good for your engine as the Diesel will also lower the octane of the gasoline but we do not have a high enough compression ratio to have a detonation problem.

The Diesel will also add a little lubricant to the fuel which is good for the engine. This amount of Diesel will not fowl the plugs or cause a model A engine to not run right.

My experience and my experience.

Chris W.
 
marc hildebrant said:
With regard to the "vapor lock never happened to me, so it can't be true..."

My Model A has always started, so anyone that hasn't been able to start their car must not have a problem...eh?

Marc
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I absolutely believe something is happening, vapor lock, or something else. Too many owners are having a problem.

Here in florida we have, hot days, cool days, high humidity, low humidity, and even "corn" fuel. My club does not seem to have any problems. There is nothing worse that a problem with no solution, especially when you read that others with the same car do not have the same problem.

I think Brent has come the closest, the problem is not a Model A problem but rather an individual setup problem. Timing, timing while driving, GAV setting, engine wear, electrical grounds, air flow, and so on and so on all make a car an individual. Some individuals have common traits.
 
Just reading this thread has given me the vapours! Living in Chicago I see what is called seasonal fuel formulation changes, or what is called winter and summer blend. Mid January the fuel has so much butane content it will boil in your hand. OK for quick sub-zero starts and no problem in injected vehicles with vapor recovery and high pressure fuel feed. Trash in carbureted anything. The 'summer blend' has a much higher vaporization point. Despite both being E10 the summer blend stuff is OK @ 100F, the winter blend stuff makes the A suffer when it hits 75F+.

My Honda lawn mower won't run on the winter blend stuff after the engine gets hot. You can take the gas cap off and watch the boiling vapor bubbles backing up from the hot carb and condensing (disappearing) into the cooler liquid fuel. Not an alcohol problem, a butane problem. Unlike propane, butane is a cat refining product with little commercial market. They try to dump as much as possible into gasoline. What is accumulated from refining during the summer, unfit for that blend, goes into the winter blend. Refining blends vary by region, refinery, and season.

Henry's 1920's - 30's gas had a significantly different vapor pressure, as did the fuel all through the carburetor era. Not too good for 0F starting, though. I'd love to join in and put the blame on ethanol, but that's not the heart of the problem. Evolving and changing fuel blends and vapor pressure specs to suit modern vehicles are the real problem IMHO.
 
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