QuestionWell, the very first thing I noticed is that the fuel line coming around under the radiator is flattened, almost completely. So first thing, I will replace that one. Will probably let you know, maybe won't get to it right away, and thanks again. Ted
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Followup To
Question -
Hi Dick - corresponded with you a few months back and appreciate your help. 1949 Studebaker starts and runs well, but as soon as it gets hot, say 160 or 170, it cuts out. Then if I pour some gas into the carb, it will start, but not stay running again till cools off. Think it is vapor lock - if it is, how do I fix that? If not vapor lock, what else could it be.
Thanks, Ted
Answer -
Yes, I agree that you have proven that it is lack of fuel that is killing the engine. The most likely cause is of course vapor lock, but there are many possible causes of vapor lock. These cars didn't do that when they were new, so something has changed.
One thing is the modern gasoline- they have changed the formula so that gas boils at a lower temperature than before - this is not a problem for modern cars because they all have a recirculation system which pumps roughly ten times the required amount of gas up to the engine, then circulates the excess back to the tank, which keeps the fuel cool. There isn't anything you can do about this, but there are a few things you should check before you go to the expense and trouble of mounting an electric fuel pump back at the tank to propel gas to the carburetor regardless of temperature.
#1 is to make very sure that all the lines and tubing on the intake side of the fuel pump is absolutely air tight. When fuel lines get rusty, or when the fuel hoses get older, they can get porous to the extent that they will not show any fluid leakage (after all, this part of the plumbing is below atmospheric pressure anyway when the engine is running), even when the car is parked and the pressure is atmospheric. However, when the pump is pumping, there is a vacuum in this tank-to-pump plumbing, and any pinhole, no matter how small, is going to admit some air. The pump cannot pump vapor or air, thus you have vapor lock - and warm gas lines add to this tendency. So check all the fuel lines etc. from the tank to the pump very carefully - if the steel lines have not been replaced, now is the time. Certainly, replace the rubber hoses too, with modern gas compatible fuel hose (it must be stamped SAE30R9 or higher, the old 30R7 can't handle the new formulations).
#2 is to make sure that all the fuel lines are routed exactly the way the factory routed them. This means OUTSIDE the frame from the tank forward, as much as possible, to keep the line cooler. This also means that the flex line from the engine end of the steel line to the pump must be new and mounted in the air stream. If your car has had a fuel filter installed in the line from the tank to the pump, remove it - these are famous for causing vapor lock due to pinhole leaks and due to the added restriction in the fuel line, lowering the pressure on the pump side of the filter, causing vapor there. If you feel you need a filter, put it in the pressure side of the pump (between the pump and the carburetor).
#3 is to verify that the fuel pump is in good shape. The best way to do this is to run both a pressure test (3 1/2 to 5 PSI at the carburetor) and the capacity test (fills a coffee can at idle in a minute or so). If it passes this test, but you know it is old enough that it doesn't have a modern rubber diaphragm, change it anyway!
#4 Just to put some old wive's tales to rest, don't bother trying to shield the line from the fuel pump to the carburetor from heat - once the fuel is up there it is under pressure, and that isn't where the vapor is formed. We see all sorts of kludgy things like clothes pins and the like on the pressure lines - this is just foolishness. Like arthritis cures, the symptoms of vapor lock are so unpredictable that almost anything seems to work for a while, but the laws of physics have not yet been repealed!
#5 If all the above doesn't lead to a cure, then you need to obtain an electric pump, mount it toward the rear of the car, where it is protected from road hazards and the heat of the muffler, preferably on the outside of the frame, but as low as you can so it will gravity feed from the tank. Plumb it in using the original type steel lines, outside the frame, and in series with the mechanical pump. Once you get the car driving on the road, you probably won't need the electric pump as long as you keep moving, so wire it to a secret switch under the dash, which gets its power from the ignition switch accessory terminal, so that when you turn off the key, you know the pump is off, regardless of the pump switch position. This will also save wear and tear on your starter, because you can prime the carburetor with the electric pump for instant starting, no matter how long the car has sat.
For a couple of anecdotes (which prove nothing), I added an electric pump to my 47 Packard limousine way back in the 60s, because I had vapor lock problems (we live in the desert, it gets well over 110 here in the summer). Once in a blue moon, I have to flip it on when I have been idling for a long time in very hot weather, such as in a parade. I also have a 48 Packard convertible, it has no electric pump, and has NEVER had vapor lock, even in parade use - in 32 years! These two cars are identical as far as engine and fuel systems - so what's the difference? I also have a 56 Packard, which has never had vapor lock except on one trip up Pike's Peak - above about 10,000 feet, I had serious vapor lock all the rest of he way up the hill - I had to stop every 1000 feet or so and let the carburetor fill up before I could go another 1000 feet, but I did make it to 14,200 or whatever the peak is. I have since added an electric pump which I use only for starting after storage for a week or more. I also had a 62 Continental which drove me nuts with vapor lock - as long as I kept driving , it was OK, but if I stopped for any reason, I was in big trouble as soon as I had restarted and driven the block or so it took to use up the gas in the carburetor! I learned to keep a cooler in the trunk with water and ice on trips, and to wrap the line right at the tank with a wet towel to cool it down to get the car going again when I had the vapor lock. I never did solve that car's problem, until I put an electric pump on it.
And one last anecdote - our 48 Studebaker Land Cruiser did the same thing, I finally had to put an electric pump on it because my wife wouldn't drive it - it vapor locked on here everytime she went shopping!
There, that's more than you wanted to know about vapor lock. Good luck with your Studebaker - just remember these were one of the most reliable cars ever built - it will be that way again when you find the right cure!
Dick
AnswerAha! Any restriction in the line from the tank will cause a drop in pressure as the gas is pulled through the restriction, and if that area is warm - Bingo! You've got vapor lock!
Congratulations, you've probably found a big part of your problem.
Dick
