vapor lock

[Guest]

No doubt this car did not vapor lock when new. Consider that gasoline in 1933 was not as volitle as it is now. Has to do I believe with vapor pressure, though for the life of me I cannot remember whether a higher or lower VP makes it more volitle. Help me out Tod.<P>I had the same problem on a '31 Cad, but of course that had a vacuum tank so the problem was confined to the fuel line, and asbestos wrap solved the problem. If I recall the '33, the fuel line runs from the front of the engine right up the valley between the cylinders, and you can fry eggs in there on a hot day.<P>As a test, the next time you have a hot day carry a bag of ice and a shop towel. When it locks put ice in the towel and chill the fuel line. If it starts there is your problem. If not, next ice down the fuel pump. That worked for me on a '40 Cad. If it is the fuel pump, you may need to build a heat shield.<P>I sincerely believe the problem is caused by today's gasolines. ~ hvs

[Guest]

I have a '33 Lasalle with a V-8 and an updraft carb that starts easy when cold but will not start when hot. The overhead manifolds create an oven in the V-8 valley.<BR>The fuel line is not insulated (Any suggestions?) and I think I have tried all the standard remedies including adding a little diesel fuel. Since the carb sits in the middle of the "oven" rerouting the fuel<BR>line makes no sense. Any help?<BR><P>------------------<BR>1932 Plymouth<BR>1933 LaSalle

[ply33]

On the assumption that the car did not vapor lock when it was delivered from the factory there are a couple of things to look at.<BR><ul><BR>[*]Is the fuel pump putting out full pressure?<BR>[*]Are the fuel lines free of kinks or bends that would trap vapor? A slight continous up slope on the fuel lines will allow bubbles to reach the carb where they will be expelled.<BR>[*]Are there any heat shielding pieces that are missing?<BR>

<BR>Just some things to look for. At least you have a great alternate car to drive on hot days. That Plymouth PB was a good car too

[Guest]

Todd and HVS ... thanks for your input.<BR>The fuel pump was rebuilt and tests to spec.<BR>There is a horseshow bend in the fuel line where it enters the carb (fuel pump is at the front of the engine but the carb entrance is from the rear.) There doesn't appear to be any missing heat shields but I don't know if the orginal fuel line was asbestos wrapped.<BR> HVS...frying eggs in that oven would be easy. I think you could put a roast beef under the carb and have it well done when you reached your destination. I tried reducing the volatility of the gas by adding diesel on a 1:20 ratio but I am nervous about doing that and I don't know what would be a correct proportion. <BR> Anybody know a source of asbestos wrap? I am getting the impression this stuff is like R-12.<BR> Todd, the PB is not just a good car but a great one. It is easier to drive around town and you don't have to wait 40 minutes between hot starts like this tank of a LaSalle.<P>------------------<BR>1932 Plymouth<BR>1933 LaSalle

[Ron Green]

You can find a cloth like wrap at most auto stores that sell performance parts or accessories. This wrap is used for high performance exhaust headers and may do the trick? You may want to make a shield that fits under your carb which will protect the heat from boiling the gas.

[Guest]

coldji ~ I used a 1 to 20 mix of diesel to gas in my 1941 Cadillac which for years had a vapor locking problem. I first used it on a hot tour in NC in 1990. It worked well.<BR>Also I was able to turn the starter faster by jumping with 12v and that seemed to overcome the vapor lock.<P>However, a recent carb rebuild by an outstanding mechanic [certainly not me] and heavier battery cables to allow the starter to turn faster, cured my problem. So if the pump is OK you might then check out the carb, and that heat shield under it might be worth a try. But first you might want to check the cables to see that they were not replaced with 12v cables by someone in the past. There is a BIG difference in wire diameter between 6v & 12v cables. ~ hvs<P>PS: That 180 degree bend isn't helping any either, but I don't know what you can do about that.<P>But then these are just my opinions. I have no credentials as a mechanic, just 52 years as a tinkerer.

[Guest]

I have a 36 Packard that also had a problem with vapor lock, and because the car is still 6 volts, it was almost impossible to start when she was hot. To overcome the problem, I installed an electric fuel pump, all the way back by the fuel tank, under the car. Now when the car is hot, I flip the switch and when the pump stops clicking, she starts on the first hit.

[Guest]

Jim ~ Do you have any problem in having the mechanical pump drawing gas through a shut off electric pump? I have often wondered about that and for that reason have hesitated to use the solution you have.~ hvs

[steve@autorest.com]

Mr. Scotland is totally correct, if the car is vapor locking, it is today's gasoline causing the problem. The LaSalle had no heat shields on the gas line or the fuel pump. Make sure that the gas line goes up the front of the engine to the carb and keep it as centered as possible in the valley away from the manifolds. The fuel pump should have the vapor dome on it, it might make a difference. If the pump is working properly with the proper pressure, you can put an electric pump on it with no problem. The mechanical pump will pull through it when turned off, with no problem. We put them on just about all of the cars we service that are used for touring. Make sure it is mounted as near to the gas tank as possible, they are made to push gas. It also helps greatly when your car has been sitting for quite a while. Diesel fuel should help, but as hvs has said, if all is correct with your engine, with the correct cables and a good starter motor etc, the car should start without it.

[steve@autorest.com]

Mr. Scotland is totally correct, if the car is vapor locking, it is today's gasoline causing the problem. The LaSalle had no heat shields on the gas line or the fuel pump. Make sure that the gas line goes up the front of the engine to the carb and keep it as centered as possible in the valley away from the manifolds. The fuel pump should have the vapor dome on it, it might make a difference. If the pump is working properly with the proper pressure, you can put an electric pump on it with no problem. The mechanical pump will pull through it when turned off, with no problem. We put them on just about all of the cars we service that are used for touring. Make sure it is mounted as near to the gas tank as possible, they are made to push gas. It also helps greatly when your car has been sitting for quite a while. Diesel fuel should help, but as hvs has said, if all is correct with your engine, with the correct cables and a good starter motor etc, the car should start without it.

[Guest]

No, I have not had a problem with the mechanical pump drawing gas through electric pump, but as of lately, I leave the electric pump on when the car is running. The pump I have is from J.C.Whitney, it's the 6 volt bellows type, and if you are going to use it, I recommend that you place it as close to the tank as possible. The way I have mine is, gas tank > filter > electric pump > filter, and then it's hooks up to the stock gas line, I also have it wired to an on/off switch, then is wired into the ignition switch. Hope this helps.

[Guest]

Jim ~ Thanks very much for the information. I have a drawer full [6] of those JC Whitney pumps, but just have not yet put one on a car with a mechanical fuel pump. I will now.<P>Steve ~ Thanks for your input.<P>I have used these pumps for years on early cars with gravity feed fuel systems. These cars are used exclusively for touring, and I have never yet had to back up a steep hill even with an almost empty gas tank. ~ Howard

[Guest]

Maybe the Lasalle won't fire because of a rich instead of a lean mixture. This problem is also very common. A hot intake manifold transfers too much heat to the carb. The gas inside the carb starts to boil and runs inside the intake. To prevent this use a thicker gasket or some kind of thick adapter plate under your carb.

[Guest]

Mark ~ Maybe that is why all the '41 Cadillacs I have had contact with over the years had about a 3/8" to 1/2" thick fibre block between the carb and the manifold. We can learn a lot on this DF can't we? ~ hvs

[steve@autorest.com]

The LaSalle can't flood when shut off, it has an up-draft carb. Any gas the would run out under those conditions would run out of the overflow drain which is in the air intake of the carb. It then runs out of the drain in the valley of the engine. However, the 41 Cadillac can most certainly flood this way. I have seen it happen quite often, and many times can be due to a weak needle and seat. The residual fuel pump pressure will push the gas past when the car is shut off and combined with the gas boiling in the carb, will cause it to start very hard when hot. Packards were notorious for this problem and they had a check valve in the intake manifold to let raw gas run out when the car was shut off.

[Guest]

Thanks again Steve. I am beginning to have a much better understanding of my "41 Cadillac. <P>There is much to be learned on here. Last month I learned something very valuable which I then ran out and applied to my wife's model A.<P>Keep up the good tech input everybody. <P>Howard

[Guest]

Thanks everybody for some great information.<BR>And especially Steve. I thought about putting a supplemental electric fuel pump in the LaSalle but like HVS was concerned the stock pump would block its effect. That is worth a try. I would hate to put heat shields when none originally existed. <BR> Thanks again, you have all been very helpful.<P>------------------<BR>1932 Plymouth<BR>1933 LaSalle

[Guest BillP]

Gents-<BR>I have two 37 LaSalles, both original V8, both original 6 volt positive ground, both equipped (by me) with electric fuel pumps. A typical cold or hot start is preceded by 5 or 10 seconds of running the elec pump to provide fuel to the carb (If engine cold, it's evaporated or leaked out, if hot I assume it's boiled off) then I hit the starter button and it starts. I usually forget to turn off the elec pump, or leave it on on purpose to avoid boiling the gas in traffic. Nevertheless, I try to remember to cut off the elec pump shortly b4 shutting down the engine to avoid residual pressure. There's no problem whatsoever pulling fuel through the turned-off elec pump with the mechanical pump on either car. One crucial thing on these cars is to ensure an excellent ground path for the battery. I have extra heavy straps from batt to frame and from engine to frame. Somehow positive ground 6 volt cars need this. After I put this extra ground on one of the cars, a hot start problem that I thought was fuel related went away entirely. Regards, Bill<P>37 LaSalle<BR>37 LaSalle<BR>34 Packard<BR>Other Junk.

[Guest]

DEAR HOT RESTART<BR>I AM A FUEL SYSTEM ENGINEER FOR ONE OF THE BIG THREE AND HAVE EXPERIENCE IN THIS AREA.<BR>I AM SURE THESE CARS HAD PROBLEMS WHEN NEW.<BR>THE BEST METHOD IS TO USE A COOLING FAN TO BRING IN OUTSIDE AIR. EITHER A FAN ON THE OUTSIDE OF THE RADIATOR OR A SMALL FAN DIRECTED AT THE CARB. HOWEVER, THE SMALL FAN NEEDS FLEX DUCTING TO BRING IN AIR FROM OUTSIDE THE ENGINE COMPARTMENT OR FROM UNDER THE CAR. 6 VOLT FANS ARE HARD TO GET. I WOULD SUGGEST A 12 VOLT BATTERY IN THE TRUNK AND A SMALL WIRE AND SWITCH TO CONTROL THE FAN. SINCE MOST ANTIQUE CARS ONLY GO ON SHORT TRIPS, YOU CAN CHARGE THE BATTERY WITH A CHARGER. THE UNDER HOOD TEMP USUALLY PEAKS AT 15 MINUTES AND IS NORMAL AFTER 45 MIN. A SMALL HEATER MOTOR FAN WOULD WORK AND IT HAS CONNECTIONS FOR FLEX HOSE.<BR>AL RUCKEY<BR>DETROIT<BR>EMAIL: A RUCKEY@YAHOO.COM

[Guest]

DEAR VAPOR LOCK--2ND MESSAGE<BR>FORGOT TO MENTION- BOTH CARBS AND FUEL PUMPS VAPOR LOCK. YOU CAN SPLIT THE BLOWER OUTLET BETWEEN THE TWO. A SECOND METHOD IS TO FASHION A WIRE MESH SCREEN (HARDWARE CLOTH) AROUND THE FUEL PUMP AND CARB. KEEP A BAG OF ICE IN A COOLER. WHEN YOU CAN'T START, POUR ICE IN BOTH MESH BASKETS THAT ARE AROUND THE CARB AND FUEL PUMP. THIS WILL COOL THEM AND THEN RESTART OK.<P>AL RUCKEY<BR>DETROIT<BR>ARUCKEY@YAHOO.COM

[Guest]

Try telling the judges that setup is original. <P>No offense ALRUCKEY, but some of us actually drive our cars, and more than a few miles at a time.

[Guest]

DEAR HVS<BR>HOW DO YOU EXPLAIN TO THE JUDGE ABOUT THE ELECTRIC FUEL PUMP ?<P>AL RUCKEY

[Guest]

ALRUCKEY, by mounting the electric fuel pump under the car, back by the gas tank, it's out of site and does not detract from the appearance of the car. Unless the judges crawl under the car and look, they don't even know it's there.

[Al Smeraldo]

I have also mounted an electric fuel pump back near the tank on a 47 Continental. There is no problem with the mechanical pump pulling through it. However if you are going to do this check to see that the pick up line from the tank has a large enough diameter. On the lincoln I had to change this line because it was too small for the electric pump to draw through.

[Guest]

ALRUCKEY ~ I just got back from Philadelphia and read your post about judges and electric fuel pumps on some of my cars. I never mix cars I have judged with cars used for touring. They are a different breed of cat.<BR>hvs

[Guest]

HVS-<BR>THANKS FOR REPLY. THIS IS THE FIRST TIME I HAVE USED THIS SITE AND I FIND IT LOTS OF FUN. WHEN YOU POST A REPLY YOU SOMETIME TAKE YOUR LIFE IN YOUR HANDS !! OR YOU CERTAINLY HAVE TO DEFEND YOUR ANSWERS, WHICH IS OK.<P>QUESTION--I WOULD LIKE TO SEND IN MY OWN QUESTIONS AND SUBMITTED FOR A PASSWORD AND I.D. OVER A WEEK AGO AND HAVE NOT RECEICED A REPLY. DO YOU HAVE THE E-MAIL OF THE PERSON WHO IS THE ADMINISTRATOR /<BR>AL RUCKEY<BR>DETROIT

[Guest]

Al, You should be able to register just by going to the top of this page, clicking on "REGISTER" and going on from there. ~ hvs

[Dave@Moon]

I've yet to meet the car that had as bad a problem with today's gas as my 1960 Buick. It has the 364 Buick nailhead big-block with the low-compression option. This option came with a Stromberg WW-2 carburator, the same tiny car found on a Willys 6 and Dodge truck 6's. <P>Shutting off the car and stopping the flow of fuel resulted in the fuel boiling in the fuel pump and probably the carb bowl as well. This resulted in raw gas dripping off of the carb linkage at a rate of 3-4 drops per second until the fuel line and bowl were empty. Can you say fire hazard? <P>I tried over a dozen carburator overhauls with no improvements. A carburator rebuilder in Missouri suggested an electric fuel pump with a switch and relocating the line away from the engine. I fabricated a line and installed a fuel pump back by the tank. I haven't lost a drop since.<P>By the way, when installing these things try to install them as low in the car as possible, which can be a challange. My Buick's lowest point is the gas tank. I had to hang the pump in a wheel well inside a thick metal box I fabricated for it. I still run out of gas (none makes it to the pump) at about 1/3 tank.