Vapor Lock 101 ?
 

Group,

I installed a rebuilt Zenith today on to my 1931 Tudor. I had a tillitson on it originally.

I had not had good power with the car and thought that the tillitson needed to be rebuilt. At Berts in Denver I saw a nice rebulit Zenith and decided to try it.

Today was 100 degree's and I'm at 5000 ft. Water boils at 200 degree's.

When I went out for a road trip, the first 10 minutes were great ! Good smooth power and a real joy to drive. Then, the motor lost power and I needed to turn the GAV a couple of turns to get home. What Happened ?

The temp of the water was 190 and it was hot (100) and sunny.

Tonight, I needed a soft serve ice cream and thought that I would try again. The car ran great...even with a run down the road around 50 MPH. Much more power and real smooth motor. The sun was down and the air temp was in the 80's.

Is the loss of power during the hot day vapor lock ?

By the way, when the motor was running bad, it could idle O.K. and when I checked the spark...I had almost 1/2 inch of spark.

Marc

Re: Vapor Lock 101 ?
 

What I believe you had happen was indeed vapor lock. Depending where you live I think you will find the gas at the pump contains up to 10 % ethenol plus possibly some other additives.Ethenol boils at a lower temp than the old gas we used to get, and even lower temp with your altitude, 5000 ft.Boiling fuel equals vapor.It is not your car or your carb but probably fuel chemistry.When it gets real hot under the hood here in Denver we have the same problem.Sounds like your carb runs great when it a little cooler.Hope this helps,Phil Turner, Berts Model A,Denver

Re: Vapor Lock 101 ?
 

Phil,

Looks like it was vapor lock after all then.

Marc

Re: Vapor Lock 101 ?
 

Vapor lock may be the eternal "tastes great!;less filling!" debate, but I once had a very knowledgeable 'A' old-timer(I hope that's not offensive) tell me symptoms attributed to vapor lock happen when a caged nut in the exhaust manifold breaks off, and heat is transferred to the carb.

Re: Vapor Lock 101 ?
 

ON the return trip from Texas in 2008 we experienced vapor lock on the sedan while traveling through Colorado. The combination you show was the same we experienced high temps high elevation et. If you switch to higher octaine gas it doesn't have the enthenol and will eliminate the problem. This was a tip from a local hot rod guy that stopped to check us out along the road when we experienced the vapor lock.

Re: Vapor Lock 101 ?
 

With all due respect to Phil and John, and just to set the record straight: First: Ethanol boils at 173F. This is almost in the middle of the distillation curve for virtually every gasoline made (gasolines boil between about 75-80F to a maximum of 437F by spec). Ethanol has its problems, but not as many as we're led to believe. Second: John's hot rodder friend was wrong: The addition of ethanol into gasoline has nothing to do with octane grade. It's added to gasoline to reduce CO emissions by chemically leaning the fuel-air mixture (more info if you want it). If you live in a CO Non Attainment area as defined by U.S. EPA (which I believe Denver and most other large cities are), you have ethanol (or another oxygenate) in every grade of gasoline because it must contain minimum 2.0 weight% oxygen. You can find out if gasoline contains ethanol (or other polar compounds) using a simple test the aviation guys use: Take a small vial and put some water in it. Mark the water level. Add some gasoliine and shake. If the water level increases, alcohol was extracted from the fuel. If not, there was no alcohol there. ;)

Re: Vapor Lock 101 ?
 

Marc, your problem may not have been vapor lock at all.

Is vapor lock a continuous thing even with a continuous, GRAVITY FED, fresh supply of cooler gas going in the carburetor from the tank? I don't think so. The carb and fuel line would have to be really hot for that to happen continuously especially while moving down the road.

Now I have seen a few complaints from people claiming the fuel boiled in their carbs after they turned off their engines on a hot day. If they start up and attempt to leave immediately, the engine will sputter and pop some until a fresh supply of cooler gas flows on in. This makes sense.

Now an engine with a mechanical fuel pump can be a different story especially in a place like CO. on a hot day straining up a steep hill or mountain. The vapor lock typically occurs at the pump itself.

But on a gravity fed system vapor lock does not make much sense in my opinion. The fuel would really have to be heat sensitive even in CO. or higher altitude.

There could have been a tiny piece of dirt or trash temporarily stuck in that carb from Berts and it passed on through.

Drive the car out again along the same route on the next 100* day and see if the problem returns.


Larry B.

Re: Vapor Lock 101 ?
 

Today in a friends car here in Denver ,air temp 101 degrees,5280 feet,same stock up draft Zenith,car started to run rough,opend GAV and it helped a little.Enough to get it off the road,We cracked the gas line and air came out.Gas could be heard boiling in the carb.After relieving the air lock and a cold wet rag on the carb it ran fine until it heated back up and the same happened again.Took it out for a ride tonight at 80 degrees no problem and ran great for 25 miles.Call it what you like but it seems like vapor lock to me.Phil

Re: Vapor Lock 101 ?
 

Larry and Marc,

In case you guys missed the earlier extensive vapor lock thread, here is a link you might find of interest:

http://www.fordbarn.com/forum/showth...k+nonbelievers

While there may be some doubt whether vapor LOCK can occur in a continuous running gravity fed engine, there is no doubt that vapor FORMATION can occur. The earlier thread shows a bunch of pictures of it happening in the top of the sediment bowl with the car idling on a summer day with the hood open. Since the initial boiling point of gasoline is around 100F, some such behavior shouldn't be a surprise. Neither is it far fetched to worry that the process might get out of hand, occur further down in the fuel path (out of sight), and cause rough running or stalling under more extreme conditions. For example, I have observed one of those clear plastic fuel filters installed in the fuel line fill up with vapor and then stall the engine--repeatedly. On the other hand, the car in the pictures barely hiccuped when the vapor bubble would periodically burp on through the system.

What mystifies me is why this is such a problem for some and not for others.

Here's one of the pictures showing the vapor bubble whereof I speak.

http://i29.photobucket.com/albums/c2...repairs043.jpg

Steve

Re: Vapor Lock 101 ?
 

If that's the case then ALL Model A's in the Denver area won't run on a hot day.

If global warming gets any worse you'll have to find a new business.


Larry B.

Re: Vapor Lock 101 ?
 

If you have one of those clear, plastic in-line filters with an "air" bubble in it, and you are experiencing vapor lock, get rid of the clear, plastic in-line filter. That might be the cause. Might not be either. If its not, go ahead and put the filter back on.

Re: Vapor Lock 101 ?
 

Old182: never thought of an oxygenate as "chemically leaning" the mixture but it makes great sense. You hint at more information: I'd like to read about it. Regards, Giles

Re: Vapor Lock 101 ?
 

Dont know if all Model As in Denver will not run on hot days but many here have this problem.Many have been frustrated enough to switch to a downdraft like a Webber carb and an electric fuel pump and have had NO more problems.I am not smart enough to tell why it is some cars and not others but every summer it has been hapening.Voodo ,or bad carma.Who knows I am only trying to help a guy out if I can.Phil

Re: Vapor Lock 101 ?
 

I always had trouble with vapor lock when using 10% ethanol and temps over 80*. I found a local station selling good gas, instead of garbage gas and the problems went away, even in 90* temps.

Re: Vapor Lock 101 ?
 

Seems to be a complex problem. I'm sure that the elevation (5000 ft) can make the problem worse with the lower boiling point.

I'm wondering just "where" the vapor is occuring.

Marc

Re: Vapor Lock 101 ?
 

"By the way, when the motor was running bad, it could idle O.K."
How could a car run good at Idle with Vapor Lock?
Larry B. hit it on the head. Remember guys, I'm a "non believer" of vapor lock in a gravity fed system. Oh by the way I was out with my coupe today here on Long Island N.Y. Temp 92* in the shade very humid and in traffic with 160*thermostat and 50-50 anti-freeze. The temperature gauge never went over 180*

Re: Vapor Lock 101 ?
 

Mark,Ther have been many Voodo cures for vapor lock from clothes pins on the gas lines to wraping lines with aluminum foil but there have been many in the Denver area who add 1/2 to 1 gallon of diesel fuel per fill up on the hottest summer days .There have been enough reliable people saying it works .I know this will bring out the nay sayers here but it has worked with our so called gasoline here in the Rockies. Again maybe this can help. Phil

Re: Vapor Lock 101 ?
 

Steve, that's quite a thread you were involved in. I was not reading much of the new Fordbarn when you posted so this is the first I've seen of it. Looks like many of them share MY VIEW and at least one with like mind is a bonafide engineer, David Cockey. I didn't read them all.

As you probably know, not all Model A's will have the same engine and engine compartment temperatures. They will vary from one to the next and there are many variables affecting each one. So before any conclusions can be definitively reached with any particular Model A, I think an actual temperature measurement of the fuel should be performed when the suspected vapor occurs. Then contact the makers of the particular fuel and find out the temperature specs. including the vapor pressure, exact boiling point, effect of various ethanol percentages and any other pertinent information necessary to determine its transition to vapor and also exactly when they change from winter to summer gas and back again and the specs. that go with each.

Then with a little effort you will probably reach a most believable and accurate conclusion.


Larry B.

Re: Vapor Lock 101 ?
 

Bob,

What I believe is that the flow of fuel has been reduced greatly due to the formation of vapor in the line/carb. What I found was that the car would idle, but with the smallest clutch action to drive, it would run very rough.
However, the adjustment of the GAV about 1 to 2 turns richer helped some.

Also, the water temp was around 190.

Marc

Re: Vapor Lock 101 ?
 

Phil,

Thanks for the information. Another thought is that we have a lower octane here in the West. I use the 87 type. It may boil at a lower temp ?

Marc

Re: Vapor Lock 101 ?
 

steve s,

I also just got finished reading the thread that you posted. I am one of those guys in the hot weather South who has never had a problem. I wish the guy with the two Model A's that has the problem and the one without the problem would try switching carbs between the cars, then switching fuel lines, etc., until the component causing the problem could be identified.

The condition of the inside of the fuel line, and/or the earlier 1 vent versus later 2 vent carbs would be my first two suspects as the cause of the condition. I sure would like to see an answer, even though I have never had the problem. Most of my driving is at sea level, but I have also driven my car in the mountains of NC and Virginia in hot weather without a problem. There has to be a plausible explanation, but I have no idea what it is.

Re: Vapor Lock 101 ?
 

The guy, who happens to president of our local club, did the experiment of swapping carbs (but not fuel lines, etc.) and reported result in our latest newsletter: The problem was NOT carb related; vapor lock stayed with the car, not the carb. Must be some subtle difference in air flow patterns in the engine compartments. It's not engine pans; others have reported problems with or without them.

Steve

Re: Vapor Lock 101 ?
 

Time to get out the cloths pins.
I know some (maybe all) of you guys just hate me........but ain't it fun!!

Re: Vapor Lock 101 ?
 

Giles: Slightly off topic, but here goes: EPA regulates 3 pollutants for gasoline engines: unburned hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). Oxygenates are compounds such as alcohols and ethers (remember MTBE?) that contain an OH group. Ethanol, for example is C2H5OH chemically. Under ideal conditions, all hydrocarbons will combust to make CO2 and water (H2O) using the equation: C7H16 + 11O2 -> 7CO2 + 8H2O. When an engine is cold the reaction often doesn't go all the way to CO2 but stops at CO (a regulated pollutant). Oxygenates in the fuel "partially oxidize" the fuel molecule by adding the OH and are said to chemically lean because they require less oxygen for complete combustion. They help the reaction go to CO2, thus lowering CO emissions. Racers who use ethanol have to increase the size of their jets to accommodate the "leaner" fuel. Pertaining to this thread, the boiling point of ethanol will have no effect on Marc's problem and I agree with Larry on most points regarding vapor lock. However, because of its volatility characteristics, ethanol depresses part of the distillation curve and THAT could lead to driveability problems under certain conditions. Hope that helps - sorry for the nerdiness :o

Re: Vapor Lock 101 ?
 

Stan, I carry my vapor lock clothes pin wherever I go just in case I encounter this problem.:p

Re: Vapor Lock 101 ?
 

True the ethenol does not effect the octane but it is not blended into the higher rated fuels. So running higher octane gets rid of the ethenol.

Re: Vapor Lock 101 ?
 

steve s,

Thanks for that update. Any chance he might be willing to try swapping out some other items, starting with the fuel line? It sure would be nice to have an answer for those who are having this problem.

Re: Vapor Lock 101 ?
 

Thanks Bob, I appreciate a good sense of humor. Also I've never had that "vapor lock" problem on my slightly modified 48 1/2 ton :eek:

Re: Vapor Lock 101 ?
 

John, I respectfully disagree. My statement regarding "...has nothing to do with octane grade..." was meant to point out that its addition to gasolines is for emissions purposes only, mandated by the U.S. EPA, and should you find yourself in a carbon monoxide (CO) Non Attainment area (most big cities), you will, in fact, have a minimum of 2 weight% oxygen in each and every grade of gasoline at the pump, regardless of its octane value. Ethanol has become the oxygenate of choice to achieve this mandate since MTBE was all but banned a few years ago. If you are away from the bigger cities, ethanol may or may not be included in the gasoline. However, ethanol has a Research octane number of 109 and a Motor octane number of 90. This puts the (R+M)/2 value, or Antiknock Index at 100 - it definitley DOES affect the octane value of the fuel, but that's not why it's in there. If a refiner makes sub-octane gasoline knowing ethanol will be added at the terminal to meet regulations AND to boost octane, it only makes sense that if the lower octane grades have it, the higher octane grades would also have it. I may have been unclear previously. No offense meant, but I believe the hot rodder is still wrong.

Re: Vapor Lock 101 ?
 

Marc,

Is it possible that you are using gasoline from last winter or have recently filled up from a station with a low volume of gasoline sales? Maybe the station is still selling "winter gas" in the storage tank!

What I am getting at is if the gas you are using is "winter gas" ... it will boil at a much lower temperature and cause vapor lock or vapor bubbles in the system at a lower temperature.

On a 95 degree day recently I opened a 5 gallon GI can of "winter gas" and as soon as I relieved the pressure the gas started to boil and continued to boil in the GI can for 3 or 4 minutes.

Cars with fuel pumps have less vapor lock problems compared to gravity feed systems because of the pressure the pump creates prevents boiling at a given temperature Just like the gas in my GI can did not boil until I relieved the pressure when I opened the can.

Re: Vapor Lock 101 ?
 

This is only true for modern setups with the fuel pump in the gas tank so it's always pushing on liquid, in contrast to the earlier arrangements with the fuel pump on the side of the motor where it often found itself trying to suck on vapor.

Steve

Re: Vapor Lock 101 ?
 

Marc:

I have a 53' Mercury and had the same proublems. I finaly gave up and put a new Carter fuel pump on the car (from MAC's). I mounted it on the frame of the car just in front of the rear wheel.The nice think about the new Carters is that they are set for between 3.5 and 4.5 lbs, so you do not need a fuel regulator. I did put a new mech fuel pump on the car too. When I begin to have proublems, I simply hit the switch for the pump and once the car picks back up, I turn off the switch and continue on with the mech pump. I did a bypass hose around the pump with a check valve from Graingers (they have a store in Denver). The check valve is a perfect fit and cheep.Yes it is not the cleanest instalation (too many hose clamps) but it works great.

Good luck.....

Re: Vapor Lock 101 ?
 

This is important to me because I took my Model A Coupe to the gas station for the first time just yesterday.
Everything was fine on the way into town, only five miles from my garage.
It was a hot day yesterday (91 degrees at the time).
I left the engine running for the fill up since I am a novice with my Model A, just building up some confidence, and I wanted to assure that I would not have problems starting a hot engine.
Well, I filled 'er up to the filler neck for the first time and drove away.
Turning away from the main drag in our little town to avoid traffic, the engine started sputtering and would not run above an idle without stalling.
I found that the only way of having a chance of getting home was at an idle!
Fortunately that little drive-train would pull some pretty good hills at an idle and I am pretty smooth with the clutch and avoided any unnecessary stoppages.
Along the five miles home, I stopped once to check the water in the radiator since the little fancy radiator cap showed red all the way to the top. I added 1/2 gal. of water which I put in the add-on trunk-box for just such an occasion.
Twice the engine did sputter to a stop along the five miles home.
The second time I could hear an air sucking sound since the engine was dead.
I traced it to the fuel filler cap. I thought it funny that a cap, which looked original, would not be venting air the way it should!
I later went on-line and learned from the site "Model 'A' Ford Garage" the difference between Eaton original vented and non-vented fuel filler caps. But, reflecting on the long five mile ride home at an idle, I came to this Vapor Lock 101? thread. Which makes me think that I had a really good case of vapor lock as the primary root cause. The non-venting Eaton cap I believe is a secondary contributing root cause.
This morning in Carthage, NC is was only 69 degrees so fired-up that beautiful Model A Coupe and, voila, no vapor lock at all, full revs, power, the whole shmear!
As I mentioned earlier, I'm a Model A neophite, still clumsy with the spark advance, mixture, choke and all that neat stuff. BUT, in my humble opinion, if it looks like a duck, walks like a duck and quacks like a duck...it's most likely a duck. Blessings to you all and thanks for all of your information in this fascinating thread!

Re: Vapor Lock 101 ?
 

joltesvig

I would STRONGLY urge you NOT to fill the Model A with the engine running.

It's very easy to fill up the tank and have the gas pour out on a hot day if your not careful. The gas, being cold from the tank, will expand and can run out the top. It happened to me......

Marc

Re: Vapor Lock 101 ?
 

This must be such a frustrating problem. I would think there would only be a few things to check. I have not seen the problem in my car, knock on wood, even in South Florida with ethanol gas.

We know for a fact that vapor lock happens when the gas boils creating an air pocket that stops the gas flow.

Can we start a list of thinks that would cause the engine compartment to get hot enough to cause the problem?

I figure we could create a list and once done, those with the problem could pick the things that their car have via a poll and see if we see anything in common.

How about;

Engine pans - they are supposed to direct air flow across the engine.
Flush radiator regularly?
Plain water or antifreeze - what ratio?
Steel fuel lines, copper lines
Color of plugs - to indicate lean running
Additional fuel filter - I'm thinking fuel would flow at a rate greater than what is used so large amounts of fuel would enter the carb be used valve would open refill the bowl, as opposed to the valve always having to be open with fuel "dripping" in the bowl all the time.
How long driven before the problem appears?
Fuel Octane
Fuel Brand

Remember we list the things first for a day or two then create a poll with all the possibilities and have those wit with problem select all that apply. Hopefully we can find an item or two that stick out.

Re: Vapor Lock 101 ?
 

FYI
Here is a link to gasoline stations in the U.S. and Canada that sells gasoline without ethanol. Listed by state, by city. Includes Brand, Octane, Street Address and GPS Cor.
http://pure-gas.org/index.jsp

It seems that cities or population areas below approximately 275K are not mandated to include ethanol in gasoline. There were no large metropolitan areas in Texas that listed ethanol free stations.

Note: 91 octane was listed by many stations as ethanol free. However, their lower/higher ocatne gasoline may contain it.

Re: Vapor Lock 101 ?
 

"We know for a fact that vapor lock happens when the gas boils creating an air pocket that stops the gas flow."

Why would an air pocket stop the gas flow? There are no loops or high spots in the fuel line. Why doesn't the air pocket rise to the top of the fuel tank?

Re: Vapor Lock 101 ?
 

[QUOTE=Mountain Dew;213610 ... Why would an air pocket stop the gas flow? There are no loops or high spots in the fuel line. Why doesn't the air pocket rise to the top of the fuel tank?[/QUOTE]

Bubbles can be sticky. Did you ever have to jiggle the sink stopper to burp the drain and get it to drain? It doesn't help the bubble rise when the liquid it's trying to flow thru is moving in the opposite direction.

Steve

Re: Vapor Lock 101 ?
 

[QUOTE=steve s;213693]Bubbles can be sticky. Did you ever have to jiggle the sink stopper to burp the drain and get it to drain? It doesn't help the bubble rise when the liquid it's trying to flow thru is moving in the opposite direction.

A Model A engine provides an ample amount of jiggle to dislodge a bubble from a gas line.

I'm sorry guys, I not buying any of the vapor lock theories. Vapor lock has never happened to me and it never will because I don't believe in it. I have had a faulty condenser and trash in the fuel tank cause my Model A to act like you described. Since I was sceptical, I looked at other things to find the problem and not write it off as the vapor lock mystery.

I don't think you will find a cure for your vapor lock. I think you can find out why your Model A is not performing like it should. Good Luck!!!!

Re: Vapor Lock 101 ?
 

Nope.....That's hocus-pocus, salami salami bolonie just like vapor lock. LOL:)