Fuel Starvation

[Ron Kansas]

OK, I know that 100 guys will jump in and say tha Vapor Lock is a complete myth, doesn't happen, 95% of vapror lock is actually ignition problems that show up when engine is hot. So let me tell you my story and see if you have any suggestions.

'29 Tudor, totally restored from ground up. Not painted over rust, but torn down and done right (by myself) Engine rebuilt by professional rebuilder with outstanding reputation. Took it on several short runs following engine rebuilder's recommedned breakin procedure. Took out on first tour today. On way out, ran perfectly, never missed a beat. (About 75 degrees when we started and about 85 when we reached our destination. On homebound trip was driving on open highway at a steady 40 MPH (3.54 rearend). Felt a slight skip/hesitation, then back to running like a clock. About 3 miles further on, stumbled and backfired, sounded like out of fuel. (Just over half a tank). Open mixture a bit but still stumbled. Pulled choke out and it smoothed right down. Opened mixture about 2 turns, settled down for a few seconds, then began stumbling. Only 5 miles from home, so by playing with choke, holding about 3/4 way out it ran well enought to make it home.

I had replaced the gas cap gasket, so wonderec about vacuum lock. Opened gas line at carb, no fuel. OK, I thought, and removed the gas cap. Still no fuel. Opened the strainer valve and got a stream of gas. Closed the valve and a few seconds later got a full stream of gas out the open line at carb. Removed carb to see if perhaps there were any problems inside, looked good, but blew WD40 through all the passages and put back together. Started right up, so took it for a drive. In less than 4 miles it began stumbling, but since I was just going around the section, headed toward the barn. Immediately opened the gas line at carb, no fuel. Began counting 1,001, 1,002, and 4 seconds later got a solid stream of gas. Took my laser temp meter. Engine 179F. Carb 146F, gas line 127F, fuel strainer 129F, intake manifold above carb 195F. It has the heater manifold, with the outer shell removed.

I am concluding that due to the ambient temperature of 92 degrees that the modern alchol laced fuel has vapor locked on me. Is that an issue with the Model A? This is my first A, so have some to learn. Other perhaps relevant facts, Total of 210 miles on engine, gas tank cleaned and lined. No residue comes out of fuel strainer or gas line, no sediment in carb bowl. Runs cool,at 92 degrees ambient, top of radiator was running at 179 degrees and bottom at 151 degrees. Engine block was 179 as well. Zenith carb rebuilt by club member who is a professional Model A restorer. Looks like it has all new jets. Running standard Model A steel gas line.

One thought I have, in the summer do I need to swap out the heater manifold for a regular manifold enenthough I have taken off the outer shell? It does appear to me to be a vapor lock, but haven't read the specs on modern gasoline to know what it's boiling point is, but with the carb running at near 150F, I gotta wonder.

Ron, Kansas

 

[James Rogers]

Put a line of cloths pins on the fuel line to ward off the vapor lock gremlins. When you find out this doesn't work, put a short stand pipe on the cut off valve in the tank and forget about it. When you opened the valve it reversed the flow just a little and the obstruction flowed back and off the pipe. This let the fuel flow and the engine ran good till the obstruction moved back over the pipe. I have seen this many times. If you blow back into the tank at the carb through the fuel line, you will get the same effect. I am in the 100% and don't believe in vapor lock.

 

[steve s]

I'm one of the ones who has seen vaporization and vapor lock with my own eyes in my Model A. Usually, it's worst when you pull up to idle at a stop light after a long run. The only time I've heard of it shutting you down when going down the road is when you've installed an extra filter in the sediment bowl, which then, due to the vagueries of surface tension the vapor bubble can stop the flow.

Otherwise, check the archives for all the pro's and cons. Here's my favorite:

http://www.fordbarn.com/forum/showthread.php?t=3803&highlight=vapor+lock

IMO, the phenomenon reminds me of PMS--folks who have not personally had to live with it are convinced that those who have are faking or making it all up. Some folks quibble over whether really-rough running qualifies as "lock". I've watched a clear plastic inline fuel filter fill up with vapor and stall the engine. For me, the final solution was the Zenith 13922 carburetor, but that's a whole other controversy.

You're right to worry about the ethanol--it is notorious for lowering the vapor pressure of gasoline. Modern gasoline starts to boil around 100 F, and then bp increases as the lighter fractions leave town. Some folks find relief with non-ethanolated gasoline; most don't have that option.

Steve

 

[marc hildebrant]

I've had vapor lock in my Model A while I lived in Colorado.
On hot day's around 95-100, I would get a reduced flow of gas to the carb when I slowed down after a high speed run down a road for a traffic light or when I pulled out of a gas station after a fill-up.

I have no idea why people don't believe that vapor lock can occur on a Model A. I has happened to me.

Marc

 

[Duffy1]

I have a clear fuel filter and have witnessed the gas to start to boil and the engine starts running rough . I moved the gas line as far away from the exhaust manifold as I could and still remain inside the hood . Seems to have helped althiugh when I stop and let the engine sit for a hile and then get start it and take off it will die of fuel starvation after going about 100 yards . Some of my club members say it is air in the line . They suggested I pull out on the choke and see if that helps . Yet ET

 

[modelAtony]

I'm one that has had this problem for 3 years off and on. When temp get around 90 here in Louisiana. It happens, you can pull off road real quick and your fuel bowl or clear gravity filter will be EMPTY. We put lots of miles on my car average 1200 miles per month before retiring drove 60 mile rountrip 5 days per week extra 300 miles so, we really drive. I usually don't mention anything on this subject because you will have many, many, people say It dont happen, IT DOES. only made comment on this subject Ron because you are really concerned. RED STICK CHAPTER BATON ROUGE,LA have fun model A tony lafayette,la

 

[H. L. Chauvin]

In my humble opinion, vapor lock can be real.

It can occur at higher altitudes where the boiling point temperature of liquids is lowered, e.g., witnessing steaming radiators full of water while climbing Pikes Peak.

It can get worse when present day, more volatile ethanol or alcohol is added to gasoline.

Even vintage planes years ago required special aircraft fuel for climbing to much higher altitudes.

Vapor lock can always gets worse in hot weather when coupled with higher altitudes & more volatile fuel.

The wood clothes pins on gas lines are not really Voodoo.

They are not just physical heat sinks which absorb metal gas line heat, thus helping to keep the metal gas lines & fuel from overheating; but if several clothes pins are provided, these additional wood clothes pins can help to insulate & deflect the radiant energy coming from the nearby manifold, exhaust, & engine.

Even though I've never experienced Model A vapor lock at our lower altitudes, if I were positive that my gas tank is clean, & my fuel is clean, living at higher altitudes with today's ethanol gas, I would not hesitate to experiment with the following inexpensive experiment:

1. Wrapping the full length of the metal gas line with an easily removable single layer of aluminum foil.

2. Getting full length(s) of rubber hose with an inside diameter slightly larger than the foil wrapped metal fuel line, thus allowing a small air space between the aluminum foil & the in-side of the rubber hose. Next, cut one side, full length, of this rubber hose so it can be easily opened on one side & installed & removed from the aluminum wrapped fuel line in winter, or for judging purposes if so desired.

3. Next, get a sheet of manila folder to use as a template, minimum 10" long x 4" wide, & custom fit this sheet first to the bottom of the intake manifold, (above the carburetor), allowing about 3/8" inch clearance, & then fit same to the carburetor with neat cut outs for the choke rod & throttle lever, & also fit & cut out for the (2) bolt holes to fit the bottom of the intake manifold & top of carburetor.

4. With the above "neat" template, scribe the outline on to a sheet of aluminum, (not steel), minimum 0.030" - 0.040" thick & custom fit this sheet to match the template. Provide one carburetor gasket above & one below this aluminum sheet. This sheet can also be removed in the winter or for judging if so desired.

Aluminum, (not steel) can work wonders in reflecting heat & also not allowing the emission of heat when placed adjacent to an air space(s).

If this experiment does not stop the vapor lock, neither will a 50 pound bag of ice; & if this does not work, look for trash in the gas tank clogging the gas valve or the gas line.

Hope this helps with peace of mind to go on another long trip with no fuel problems.

 

[Ron Kansas]

Thanks for the responses. I am certain that it is not sediment in the fuel, as I can simply wait for 5 seconds then a full 1/4 inch stream of gasoline flows steadily. I drove into the shop with the engine starving for fuel, cut the ignition without touching the fuel valve. Immediately opened the gas line at the carb and found no gasoline flowing for a full 5 seconds, then a full stream. Obviously no obstruction in the system or it wouldn't have started on its own with no blowing. Removed bottom of Zenith carb, almost no gas in the bowl. The original type steel gas line is routed as it came from factory. I did put a splash pan in on both sides. I am still wondering about the amount of additional heat dumped into the engine compartment wiht the heater type exhaust manifold, even with the outer shell removed. Seems to me like the purpose of the heater manifold is to radiate heat for use in the passenger compartment in the winter. In the summer without the outer shell that same heat is dumped into the engine compartment. When I caught fuel in a clean container out of the strainer, perfectly clean, no sediment. Same with the gas coming out of the line at carb. I am surprized at the temp of the carburetor, and again wonder if part of the cause is the heater manifold holding more heat in the manifold instead of letting it out the exhaust pipe. By the way, new exhaust pipe and muffler from one of the big suppliers, not sure if it was Mac's or Snyder. From my years of experience with engines, I am certain it is fuel and not electrical. Pulling the choke immediately shows favorable results, and letting it off immediately results in complete shut down. Electrical just doesn't respond to choke settings that way.

Again, thanks for the responses and suggestions. I heard the gentleman describing the obstruction over the tank outlet pipe. As a kid on a farm in Iowa, recall the DC Case tractor shutting down over and over. Blow on the line and it would start and run perfectly. Finally removed the tank and turned it upside down. Found a soy bean that would roll over the out let and work like a check valve. But, without doing anything but removing the line from the carb and waiting for 5 seconds, I get a full flow. Like many of you, I do believe the idea of vapor lock is way over played. I just don't have that much experience with gravity fuel systems. The farm tractors had gravity systems, but they were out in the open and never got any warmeer than ambient temps, while the Model A is housed in a very hot environment. Would any of you suggest removing the splash pan to improve cooling of the engine compartment??

Thanks again, Ron

 

[mass A man]

Ron, I, too, am running an original '31 Model A with my "Auto lite cover off" for the summer, as usual. With splash pans. It was 87 degrees in the Boston area today, had truck out and running for some time at around 40 MPH with no issues. BUT--- my gas pumps around this area state there is 10% Ethanol in my fuel. How much Ethanol is in your gas? This may be the problem here. One thing I've done a long time ago was to put a length of "lagging" on my fuel line- to- carb.The old timers called it that. It consists of the type of wire loom one can purchase at any of the Vendors that is black lacquered woven loom. This may help your problem too. Most old cars used this "lagging' on fuel lines under the hood, but people have removed them or they rotted off. Aircraft still use them. I've seen many funky things people have used, many times friction tape wound around the lines. I haven't had vapor lock on a Model A of mine, but have seen it happen on an old Dodge with a block mounted mechanical fuel pump. Good luck on this and have a great Memorial Day.---Pete.

 

[Tom Wesenberg]

Years ago I didn't think vapor lock could happen with the Model A gravity feed, until it happened to the 29 Tudor I was riding in. It also happened to me when the temp is over 80 and if I have the corn crap gas in the tank.

I got some help by slipping white plastic tubing over the fuel line. I never had the problem once I found the good gas without corn in it.

 

[steve s]

... . Would any of you suggest removing the splash pan to improve cooling of the engine compartment??

Thanks again, Ron

Ron,

I have followed the numerous threads on this topic for several years, and my impression is that the splash pans are irrelevant: many reports of people with or without them having or not having problems. I don't have them in my car.

I follow your logic about the manifold heater dumping extra heat into the engine compartment. I'm sure that, as with the engine pans, there must be cases of folks with and without that setup both having and not having problems. For example, my mom's '30 coupe has the manifold heater, and simply insulating the fuel line (see next post) has sufficed for her car.

The ethanol/gas really does seem to aggravate, if not in some instances totally cause, the problem, but, strangely, not for everyone. By the way, the problem with ethanal is not due to its own volatility; it actually causes the gasoline molecules to evaporate more rapidly when mixed with them--a case of forced integration not working at the molecular level.

Steve

 

[steve s]

...

Even though I've never experienced Model A vapor lock at our lower altitudes, if I were positive that my gas tank is clean, & my fuel is clean, living at higher altitudes with today's ethanol gas, I would not hesitate to experiment with the following inexpensive experiment:

1. Wrapping the full length of the metal gas line with an easily removable single layer of aluminum foil.

2. Getting full length(s) of rubber hose with an inside diameter slightly larger than the foil wrapped metal fuel line, thus allowing a small air space between the aluminum foil & the in-side of the rubber hose. Next, cut one side, full length, of this rubber hose so it can be easily opened on one side & installed & removed from the aluminum wrapped fuel line in winter, or for judging purposes if so desired.

3. Next, get a sheet of manila folder to use as a template, minimum 10" long x 4" wide, & custom fit this sheet first to the bottom of the intake manifold, (above the carburetor), allowing about 3/8" inch clearance, & then fit same to the carburetor with neat cut outs for the choke rod & throttle lever, & also fit & cut out for the (2) bolt holes to fit the bottom of the intake manifold & top of carburetor.

4. With the above "neat" template, scribe the outline on to a sheet of aluminum, (not steel), minimum 0.030" - 0.040" thick & custom fit this sheet to match the template. Provide one carburetor gasket above & one below this aluminum sheet. This sheet can also be removed in the winter or for judging if so desired.

Aluminum, (not steel) can work wonders in reflecting heat & also not allowing the emission of heat when placed adjacent to an air space(s).

If this experiment does not stop the vapor lock, neither will a 50 pound bag of ice; & if this does not work, look for trash in the gas tank clogging the gas valve or the gas line.

Hope this helps with peace of mind to go on another long trip with no fuel problems.

Here's a picture of one of the many straws I grasped at to fight vapor lock, along the lines of what you suggest. The heat shield was made by a friend in our club, who passed it along to me after he discovered that most of his problem was due to retarded timing. The second photo shows my own attempt to insulate the fuel line and sediment bowl. The duct tape was applied over lengthwise-slit rubber hose put over the steel fuel line. These efforts all helped, but not completely.

Steve

 

[H. L. Chauvin]

Hi Ron,


In your comment:


"I am still wondering about the amount of additional heat dumped into the engine compartment with the heater type exhaust manifold, even with the outer shell removed."


In my opinion, while you are traveling down the road at 40 mph with a fast turning fan behind the radiator, & having exhaust fins with over twice the open exhaust area as the radiator intake open areas, on both sies of the hood, whether using a heater type exhaust or not, with this many air changes per minute, in this small area under the hood, your heater type manifold will not generate enough heat to make a difference.


Appears similar to having an enclosed bedroom with a large window fan on one side, & a large window opened on the other side, when it is 100 degrees F outside, & with this many air changes per minute, the bedroom temperature will not vary much whether you have one (1) or two (2) bedroom window units running.

If the "aluminum" sheet is difficult to find, ebay has a K & S sheet. .032" x 4" x 10" for $1.79.

In the Steve's photo above, appears the sheet metal near the carburetor is galvanized steel -- galvanized sheet metal will not reflect heat nor radiant energy, but will absorb & give off heat. Also the aluminum sheet metal has to have the large heat reflective area between the carburetor & the hot manifold, as opposed to between the carburetor & the cooler valve chamber -- one can hold one's hand on the valve chamber, but not on the exhaust manifold.

Over 30 years ago I lowered an attic's temperature a whopping 55 degrees with "aluminum" radiant barrier -- from 150 degrees F to 95 degrees F at noon on a 100 degree day. Attic amazingly still stays 5 degrees cooler than outside temperature. This radiant barrier technology is just beginning to surface a little today -- it has been around since the 1920's.

In a Model A shop or garage, the sun's radiant energy goes right through a galvanized steel roof & heats up the slab below -- then at night, the slab heats the shop. A thin aluminum radiant barrier under this roof is more effective at reducing radiant energy than the shade of a large oak tree above the roof.

Just an opinion -- everybody has one!

 

[steve s]

Hi Ron,
...
In the Steve's photo above, appears the sheet metal near the carburetor is galvanized steel -- galvanized sheet metal will not reflect heat nor radiant energy, but will absorb & give off heat. Also the aluminum sheet metal has to have the large heat reflective area between the carburetor & the hot manifold, as opposed to between the carburetor & the cooler valve chamber -- one can hold one's hand on the valve chamber, but not on the exhaust manifold.

....

You're right, my shield was sheet metal. Also, in agreement with your reasoning, my friend's replacement shield was simpler design (still sheet metal) that just focused on shielding the exhaust system.

If the metal used is so important, I wonder why Leslie Pam uses galvanized sheet metal in his Kool Foot muffler heat shield. Also, my impression is that muffler/converter heat shields on modern cars are sheet metal.

 

[Kurt in NJ]

I am in the catergory of "I never have vaporlock", since I live in NJ all the gas has been diluted, since I use a cast iron sediment bowl I never see bubbles in the gas, I do have a cracked ex manifold that blows ex on the carb bowl, once I thought I was having "vapor lock" but it turned out to be closed up points.

I have been working on a BMW Isetta, it has the same type of fuel setup as the A(same pump-gravity), i was told to never use a paper filter on it because it would cause "vapor lock", to only use a screen for a filter.

Look at your fuel lines, there should be no high spots to trap bubbles, it should all angle down, check the ends of the fuel pipes----there should be no burrs from where the tubing was cut ---think of the hamster water bottle, the end of the tube is narrowed some, that keeps the water from dripping out.

 

[Benson]

Ron,

1. Are you using gasoline from last winter? Several sources have told me that winter gas boils at about 100 degrees. Summer gas boils at about 140 degrees.

2. Anything that creates more heat makes problem worse.

3. Are you running gas adjustment valve at 1/4 turn? If closed mixture will be too lean and more heat. Then when airflow slows down the gas boils (sometimes called "hot soak" when vapor lock happens when stopping engine for a short time).
Ford designed the Zenith to run at 1/4 near sea level so that one could close down the GAV at higher altitudes as needed.

4. Restricted fuel lines? Ferrels on fuel line with line sticking out too far on end of line against the filter screen on carb end or against the sediment bowl on the tank end. 1/8th to 3/16ths inch is about right.

5. Inline filters can restrict fuel flow as most inline filters are designed for a fuel pump. Gravity feed can be slowed down when car is at speed by the wrong filter or too many filters. Then when you slow the down air flow, the engine heats up as does the engine compartment.

6. Main jet in carb partially plugged will run lean at speed (above 35) then when you slow the airflow through radiator the engine gets hotter.

7. Brakes dragging?

8. Running with timing retarded.

9.Timing too far advanced?

10. Restricted muffler?

Two stations in Wichita have ethanol free gas in all three grades. One with regular only.
http://pure-gas.org/index.jsp?stateprov=KS

Check the "details" column on far right as some stations list the grades there and not in the "grades" column on the left.

 

[Benson]

I am in the catergory of "I never have vaporlock", since I live in NJ all the gas has been diluted, since I use a cast iron sediment bowl I never see bubbles in the gas, I do have a cracked ex manifold that blows ex on the carb bowl, once I thought I was having "vapor lock" but it turned out to be closed up points.

I have been working on a BMW Isetta, it has the same type of fuel setup as the A(same pump-gravity), i was told to never use a paper filter on it because it would cause "vapor lock", to only use a screen for a filter.

Look at your fuel lines, there should be no high spots to trap bubbles, it should all angle down, check the ends of the fuel pipes----there should be no burrs from where the tubing was cut ---think of the hamster water bottle, the end of the tube is narrowed some, that keeps the water from dripping out.

I have seen this where a fellow had a couple of loops in the gas line that collected bubbles as Kurt mentioned. I had a rubber line for a while last year that had a dip in it similar to a "P" trap on a sink ... it had vapor lock problems also.

 

[H. L. Chauvin]

Hi Steve,

Even with today's technology, an aluminum radiant barrier cannot be assigned an R value or U value like that of fiberglass insulation because of current standards based on BTU per hour calcuations.

All that is recognized through scientific thermal experimentation is that an aluminum radiant barrier can reflect 97% of radiant heat, (radiant energy), when provided adjacent to an air space.

Aluminum heat shields can & will far out perform steel heat shields. A muffler shield made with aluminum will reflect over 90% of the muffler's heat -- does it cost more to construct? Yes.

If you ever are "sincerely" interested to "see" & "feel" the difference, between aluminum & steel's properties with regard to heat dissipation, go to a metal roofing supply place & buy one sheet of 4 feet long aluminum roofing & one 4 feet long sheet of galvanized steel metal roofing.

Place both directly facing the sun about 6 feet above ground on a 90 degree day. After one hour, stand under each, then place your hand on the bottom side of each. How confident am I that you will experience an enormous difference? I would not hesitate to bet a fully restored 1930 Towncar.

If Thomas Edison would have gone to college, his professional college professors would have taught him what they learned from their former college professors, i.e., that making a light bulb & a phonograph was physically impossible -- kerosene lamps & live music were here to stay -- but he chose to experiment & listen from within.

I hear what you are saying about current automotive heat shields, but if you conduct the above experiment, you will agree with what I have found & learned after over 55 years of experiments in construction management & working with other professionals:

Like the song: "God is great, beer is good, & people are "not" crazy -- they just don't listen."

 

[1931 flamingo]

What type of filter are you using?? Orig type sediment bowl, glass bowl, glass bowl w/paper filter?? Try taking whatever type filter you have (you say your gas runs clean) out of the equation and see what happens. Nothing to lose.
Paul in CT

 

[Ron Kansas]

Not running any filters of any kind other than what Henry put in at the factory. Cleaned the tank and lined it, new strainer inside tank on top of the fuel shutoff valve, and cleaned and installed new drain valve in the original cast sediment bowl. Then use a Snyder's steel gas line from the sediment bowl to the carb. No filters of any kind. Opening the sump on bottom of cast sediment valve results in perfectly clean gasoline. However; when I saw gasoline prices rising early last winter, I filled all my spare gas cans, so without thinking about the long term results (I did add STABIL to the cans) I am using winter fuel. Will drain tank and re-fill from fresh supply. I am reluctant to drive to the only two stations in Wichita that carry real gasoline as that option won't be available on tour, I will have to use what is available along the road, so I want to get it running with the corn crap. (By the way, I used to run the design department at Coleman and know about the miseries caused by the modern fuel additives and the alcohol. Raised real havoc with the Coleman Fueled appliances, caused lots of re-design.) I am going to follow some of the good advice you all have so kindly offered. I will insulate the fuel line and build a heat shield above the carb and the exhaust pipe, then give it a go.

Although I haven't done it on this car as yet, I habitually run about a pint of Automatic Transmission fluid to 20 gallons of gasoline as a valve lubricant. BG Products has their main factory in Wichita, our club did a tour of the facility, and while visiting with the head of the lab, some one asked him what he thought of MM oil. He responded, "It is an excellent product! Works very well for it's intended purpose. In fact, we can hardly find any difference between MMO and Auto Trans Fluid, except that it is about 6X the cost." So, I have used the cheapest auto trans fluid in my fire truck, Ferguson tractor and 216 Chevy engine, stopped the problems I had with brand new valves hanging in brand new guides.

Thanks again to all the persons who listened to my problem and offered suggesions based on personal experience. I was pleased that it didn't degenerate into an argument about the validity of the term "vapor lock."

Plan to take it for a run tomorrow evening and show it off at extended family picnic, so should get an opportunity to give it a good test on a forecast 95 degree day.

Ron