Question: My wife bought a new Oldsmobile Delta 88 in 1983. It is used only occasionally, having 2,800 miles on the odometer. After setting several days, we almost have to run down the battery to get it started. Pumping the accelerator doesn’t help. Have you any suggestions?--W.E.J.
Answer: Your problem is that the small amount of gasoline that is stored in your carburetor is evaporating on the days your car is not used. The carburetor float bowl stores about two tablespoons of gasoline, which is enough to get the engine started and the fuel pump supplying additional gasoline.
The gasoline is evaporating through vent holes to a charcoal filter, which prevents the gasoline from evaporating into the atmosphere and causing air pollution. There is no way to block these vents.
As you have found, it requires a lot of engine cranking to pump gasoline from the fuel tank to a dry carburetor. Eventually, that will wear out your starter motor and battery.
If you are planning to drive your car infrequently, it is probably wise to just start the engine every four days. That will keep the float bowl filled and eliminate much of your problem. At the rate you are driving, your car will probably last 50 years.
Q: We have a three-quarter-ton Chevrolet truck, 450 engine and 400 transmission. Mechanics have tried everything to eliminate our vapor-lock problem, including putting in a new electric fuel pump, insulating the fuel lines, moving the fuel pump to the outside frame. The only thing that works is to wrap the fuel pump in wet rags. Is there anything else we can do?--W.G.C.
A: You aren’t the first GM customer to experience this problem with your engine/transmission combination. GM has conducted a lot of research on how to eliminate it, especially on the chassis it supplies to motor-home manufacturers.
Vapor lock occurs when the engine heats up gasoline before it reaches the engine and causes it to boil inside the fuel lines, fuel pump or carburetor, resulting in a block in the fuel system. Once the vapor has developed, it is often a frustrating and lengthy wait for the gasoline to cool down and condense.
Your letter indicates that you live at a high elevation, which is probably compounding your problem. At high altitudes, all fluids boil at lower temperatures. Also, mountain driving puts a lot of load on an engine, causing higher engine temperatures.
One potential fix to your problem is to try different brands of gasoline, because they all vary in their volatility. Gasoline companies market less volatile gas in the summer when ambient temperatures are high, but that doesn’t always make up for high elevations.
I would not suggest adding diesel fuel, as it could damage the engine in some unknown area.
To keep the gasoline cooler before it reaches the engine, you might want to position the electric fuel pump as close to the fuel tank as possible. Also, use one-half-inch-diameter fuel line up to the front of the car and run it along the outside frame. You should also install a pressure regulator to make sure excess gas isn’t being forced into the engine.
Ralph Vartabedian cannot answer mail personally but will respond in this column to automotive questions of general interest. Do not telephone. Write to Your Wheels, You section, The Times, Times Mirror Square, Los Angeles 90053.