QuestionI did as you suggested and fuel did flow through the line. I have also noticed one othe interesting symptom. The car possess a fuel pump that fills the vacuum tank after the car has been sitting for awhile. If I push the button which activates the fuel pump the vacuum take fills in about 60 seconds. After the vacuum take is filled I can start the car and it runs just fine for a couple of minutes then the car "seems to run out of gas" Is it poosible that the vacuum pump is not functioning? is is possible that the line leading to the vacuum pump may be partially blocked? any help appreciated. Marc Followup To
Question -
I have a 1930 Cadillac 5 Pass Sedan. I am having issues with the fuel system. My car was running quite weel, but recently I can not keep the car running. I am underthe impression that some foreign object may have gotten into the carberator, preventing fuel to entering. How can I trace the problem? Any help would be greatly appreciated. Thanks
Answer -
First, disconnect the fuel line that goes into the carburetor, and place a container so as to catch any fuel that spills during the following steps:
Crank the engine, and note whether there is a repeated, periodic spurt of gasoline from the fuel line. If so, there is no blockage prior to the carburetor.
Next, connect a substitute fitting to the carburetor inlet and blow hard into the fitting (use a short length of rubber hose to make this easier).
If you can blow into the fitting easily, there is no blockage. If you cannot blow into the fitting, there is probably a problem with the inlet valve or the float system.
As a diagnostic trick, try rapping on the fitting area of the carburetor with the plastic handle end of a screwdrive or the like (the plastic handle, nothing metal!). You may dislodge a stuck needle valve and the car will now run normally again when you hook everything back up, after cranking long enough to refill the carburetor. However, if this is what happens, the problem will return sooner or later, so you will have to have the carburetor rebuilt, or be prepared to jump out and rap on it once in a while.
If none of this sheds any light on the problem, post a follow up question and we'll take it to the next step.
Dick
AnswerI was not aware that Cadillac was still using the vacuum tank type of fuel system as late as 1930 - the cars I have worked on from that era were all Packards, and they had gone to a modern mechanical fuel pump by 1930.
So, in answer to your question, it is very possible that the vacuum tank is not working. The electric pump is most likely something a previous owner has added, perhaps for this reason.
The vacuum line which operates the factory supplied fuel system is supplied from the engine intake manifold, thus there is a chicken/egg problem - there will be no vacuum unless the engine is running, but the engine will not start with no fuel. It is for that reason that the vacuum fuel system has a storage container that will run the engine for a few minutes once it is filled.
When the cars were new, that worked out fine, because they were driven frequently, and the stored fuel in the vacuum tank was always adequate to get things going again. As these cars became collector cars, and were required to sit for weeks or months without running, this sort of problem began to crop up.
In your case, I suspect the vacuum system is not functioning, other than as a temporary fuel storage device. These are tricky to service, and you will have to find a specialist to take care of it, unless you can detect something obvious (like for instance the vacuum supply line from the engine being blocked or disconnected).
You can, if you wish, change the switch from a push button to a toggle switch so you can run the electric pump continuously - that will make it possible to drive the car, even though the pump noise might be unpleasant.
If you determine that the vacuum tank system needs service (by finding that vacuum is present at the supply line, yet it won't keep the carburetor supplied with gas), you will need to contact a knowledgeable rebuilder to fix it for you.
Since I don't know where you are, I can only suggest the following: If you don't have a person you trust to service this item, I recommend a shop in Eldon Missouri called "The Carburetor Shop", owned by a man named Jon Hargrove. I'm not certain they work on these old vacuum systems - but I'm sure they would be able to recommend someone to you. You can contact them at:
TELEPHONE - (573) 392-7378 (8-4 Mon-Wed central time).
I hope this is of some help to you. At least, we have eliminated the carburetor as a source of your problem.
Dick
