News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

vapor locking( 1939 sedan)

Started by ron pletsch, August 16, 2005, 05:47:55 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

ron pletsch

I have used wrap around the crossover pipe from McVeys, and used a hot rod cover for the fuel line, and it still vapor locks.  It usuall happens after about 20 minutes of running .  I limp home in first gear.   any suggestions.

Porter 21919

Ron,

Scroll down to the post about an overheating 1959, that should give you some answers.

An electric fuel pump will cure your problem. Its not an irreversible modification that will devalue your car. At least you would be able to drive it in the hot summer.

Porter

Bill Ingler CLC 7799

Hi Ron- After you scroll down and read all the postings on the 59 overheat that Porter suggested, please come back and tell us if you have an electric aux pump installed on your car. The correct type electric pump properly located on the car will allow you to pressurize the line to break a vapor lock. With the low flash point on todays blends of gas you will at times develop a vapor lock but now with the electric pump in the system you can turn on the electric pump, pressurizing the line, eliminating the lock and enjoy your car. Most of the vapor locks are in the engine pump. Most of the auxilary electric pumps on the market are what is known as pusher type pumps. They do a good job pushing the pressurized fuel through the line and a so so job of pulling the fuel from the tank. This is why the electric pump needs to be located as close to the fuel tank as possible and not on the frame under the front door far from the tank. Insulating the fuel line from the engine fuel pump to the carb might give you a warm fuzzy feeling of comfort but little else. Without an electric pump in the system the only pressurized line is from the engine pump to the carb.If that line is not getting fuel because the vapor lock is in the engine pump, you can insulate all you want or use clothes pins on that line and you still have not cured the lock in the engine pump. Pressurize the fuel line from the tank to the engine pump, then the engine pump now has the fuel to pressurize the line to the carb. If you drive in slow traffic like a parade,I have seen a return line routed from a T on the inlet to the carb back to the filler tube to the tank. This with an electric pump gives a continuous flow of fuel in the system.

Porter 21919

Bill,

It is always nice to be able to drive the car dependably, usually in the summertime when it is hot, when most of our cars get driven.

Up here in Maine vapor lock is not so much of a problem, in your neck of the woods, Southwestern ,not the same story.

Nothing wrong with adding some newer hi-tech modifications that can be done without drilling any holes or creating any irreversible modifications that will alter the authenticity of the factory car.

Cars were meant to be driven, reliably, dependably and enjoyably. Well, even if we have to make some reversible hi-tech modifications. Henry Leland would approve, maybe even trailer queens, who knows ! LOL Always save all your old parts.

Porter







Bruce Reynolds # 18992

Gday Ron,

I dont think that Vapour Lock is your problem here.

That is because you say that you can limp home in first gear.

Vapour Lock will cause the engine to physically stop, and wont start until things cool down and the fuel can start flowing again.

I would be looking at something like an ignition component, eg. the coil, as the culprit.

Bruce,
The Tassie Devil(le),
60 CDV

Bill Ingler CLC 7799

Hi Bruce- You can get vapor lock and not cause the engine to shut done. One of the most ideal times to get vapor lock is sitting at a traffic light, pull away in first, shift to second and get jerking and bucking.Unless you have an electric pump to clear the lock, you are forced to back off on the power. The car runs  in first but your asking for more fuel in 2nd than you can get from the engine pump.You have a intermitent moving vapor lock, so you limp home the best way you can, in 1st gear if that is necessary.And yes if the temp is high and you can`t get the car to speed to help the cooling then you could get a complete lock which would shut down the engine. You might be right Bruce,Ron might have another problem but a vapor lock does not necessarlly mean the engine quits entirely.

wayne CLC 17724

Sorry to hear about your vapor lock problem. I had an experience with my .39 60S that acted like a vapor lock but was not. Turned out that it was a small vacuum leak in the fuel line. Not enough to leak gas out but enough to allow the fuel pump to draw air into the line along with the gas. I have a fuel pump with the glass filter bowl and you could see the air bubbles . Once I retightened all the connections, no air bubbles. I do believe in the use of the electric pump for emergencies. It also makes the car much easer to start after it sits awhile. I have used the same pump on all my cars because it is of an in line type with filter attached. It has a 2 wire connection so it will work with either + or - ground. NAPA has them. Airtex #E8011 for 6volt.,12volt is also available. I also use a preassure regulator attached to the output side of the pump set at one half to one pound below the mfg. suggested output preassure of the stock pump. You can put a separate switch on this pump because your stock pump will pull through it.
 Good luck, Wayne.

Bruce Reynolds # 18992

Gday Bill,

The only time I have ever had Vapour Lock and the car still kept going was on one hot day, in crawling traffic, and the outside temperature was 110F.   As soon as I got up to 10 mph, there was enough airflow underneath the car to allow the vapour to cool down and normality came back.   The Bucking and oh my God only lasted for about 40 yards.   And, I was using that electric pump up on the inner fender as my only source of fuel movement.   In my case, the vapour was in the line under the car.

But, I wonder if his fuel tank level was low, and everything back there was heating up.

Bruce,
The Tassie Devil(le),
60 CDV

Roger A. Zimmermann #21015

Its not my opinion either, the engine can run with almost no load. Not well usually, but it can run.
The recent messages about this topic are very interesting, even if I still dont have the solution to my own vapor lock problem!
Since my 56 Biarritz can be driven, Im annoyed with vapor lock.
Once, while driving on a freeway a rather warm day (for Switzerland), the engine died at 50 mph. Due to previous experiences, I had cold water with me. I poured some water on the fuel pump and I could go home without trouble. Because of this experience, I decided to let install an electric fuel pump under the frame, in serie with the mechanical pump. There was some improvement, but marginal. Somebody from this forum wrote that the pump should be installed in parallel to the mechanical one, which I did last winter.
Last week, I took the car home (the garage for the Cads is at about 10 miles from home) without problem; the next day, I went back to my garage. At arrival, I parked the car outside, discussed with a man doing some work on a early 50 Opel, closed the roof of the Biarritz. After about 3/4 of an hour, I wanted to park the car in the garage. The engine ran almost immediatly, but when some effort was required, it died. After a while, I did something else and after 2 hours, I tried again. It ran like a charm, without hesitation or bad manner.
The next thing I will do is to replace the thermostat with another one which open at 160°F. If no change, I will disconnect the mechanical pump and rely only on the electrical one. Next, a return line will be added...Projects are not missing!
The design of Cadillacs from this time was not bad at all, with the exception of the position of the fuel pump. Why put they the pump from 1954 to 1962 almost above teh engine, exposed to the engines heat? Totally stupid and irresponsible!
By the way, Im surprised that the 39 Cad, with a well placed fuel pump is also doing vapor lock. The lock may develop in the fuel line above the pump, or in the carb itself. Sometimes ago, I read in a French magazine that an owner of a prewar European car is surronding the carb with a wet rag.
Who knows, maybe some day I will be able to drive without anxiety. By the way, I dont have difficulties with my 56 de Ville (1-carb set-up) not with the 57 Brougham.

Roger

Chuck-#21953

I had exactly the same problem until I installed a 6-volt Airtec pump.  However,I could not get it to run reliably through the mechanical  pump as others have done.  Now,I have bypassed the mechanical pump and the car runs like a dream.  I was told to never run more than 4 PSI. I run 2 1/2 PSI.

John Washburn

Chuck,


I wonder about the advice you received on the pressure you should provide to the carburetor. For a 1939 Cadillac V8 it is 4 1/2 Pounds Pressure provided by the fuel pump. It should be the same for your electric pump.

2 1/2 pounds pressure might work, but for maximum effeciency you should kick up the pressure. I assume you are using a pressure regulator, so it is easy to change.

Good Luck

John Washburn
CLC #1067

Remember change all rubber gas lines to the new 30R9 (fuel injection line) to prevent failure of the line from our new alcohol rich fuels.


Bill Sullivan

This topic has been beaten hard but not to death.  It will not go away, all of these flatheads seem to do battle with vapor lock.  Everything from tin foil to clothespins on the fuel lines have been suggested.  Most of these tricks dont work, though they may appear to in the short run.

I must agree with Chucks comment on bypassing the mechanical fuel pump completely.  I have driven my 40 LaSalle thousands of miles in very hot weather at high altitude (I live at 5500 ft and often drive in the mountains).  It has been configured with just the mechanical pump (original), with either autopulse or Carter rotary electric pumps at the tank in series with the mechanical pump, electric pump in parallel with the mechanical pump, and electric pump only, completely bypassing the mechanical pump.

The last setup has given me the best results.  It appears that the mechanical pump acts like a boiler, it is very hot and attached to the engine.  Fuel going through it gets totally bubbly and worthless, even with an electric pump pushing the mess into the carb.

With the electric only setup, on a hot start the engine will still run poorly for a mile or two, but entering fuel eventually cools the carb and she smooths out.  I also make hot starts initially with the electric pump turned off, because she has a tendency to be flooded from the fuel that boiled off from the bowl while sitting.

I have found that the flow capacity of the autopulse pump alone is too small to support the engine under full load climbing long hills.  If you go electric alone, make sure you get the more expensive rotary pump, it can move far more fuel than that noisy clicky little autopulse.

Good luck!  Youll probably need it.

ps the more ethanol we get in the fuel, the bigger this problem seems to become.  

WILLIAM kING

Wow! We all suffer from the vapor lock issue.

I installed a 4 pound electric pump and when the engine dies, I simply go to neutral, let the car roll, turn on the pump and after a few second go to 3rd gear again and let the clutch out. I has not failed me yet.

Bill K. CLC # 20336

John Washburn

Wayne,

Makes an excellent point, if you see bubbles in the fuel pump filter you have problems.

Seems after 60 or so years the gas lines open up a little and suck air with the gas, connections get old at the gas tank, the fuel pump rubber lets go, and any number of other gremlins attack the system.

If you see bubbles, work to get rid of them, the car will run so much better. It could be gas lines (the metal ones, or the rubber ones - use only new fuel injection gas line or you will pay the price).

Ive tried both methods of routing gas lines when I installed an electric fuel pump. Bypassing the manual pump or pushing it through seem about the same here in Colorado at 6500 when it gets really hot.

Come see us we can discuss this in person.

John Washburn
CLC #1067

a friend of Porter...