Packard Forum Index » Pre-War (1899-1942)

Today I had again a typical problem. I drove my OneTwenty 1936 for about 40 minutes. Arrived at home, I stop the engine briefly to open the garage door. After that I needed almost 5 minutes until the engine started again. I have an electric fuel pump as an add-on that I always turn on before starting and turn off when driving. No matter with or without choke, the engine starts again very difficult when warm. Cold start usually works better.

If the starter cranks the engine as it should when hot, most hot starting issues are related to flooding.

The carburetor may leak fuel into the intake, flooding the engine, then not have any fuel in the bowl once the flooding condition is eliminated.

The electric fuel pump should eliminate any vapor lock issues, but vapor lock in hot weather is often a problem. In some instances, an electric fuel pump can have too much pressure for the application and contribute to flooding.

The carburetor may have internal leaks, a high float level, or it may be boiling over to to excess heat under the hood and the low boiling point of most modern-day gasoline.

The 120 has a thermostatic intake manifold heat valve, and if the valve is sticking shut, which they often do, it will cause carburetor boilover, usually after a brief stop in warm weather.

The 120 also has an unusual, small drain pipe on the intake manifold, which is designed to reduce flooding. It has a check valve at the lower end, and if the check valve is stuck or plugged up, it will increase the tendency of the engine to flood.

A shop manual is a good thing to have. Reprints are available and the various manuals can be found in the Literature Archive on theis website.

Your car may stast more easily after a brief stop if you hold the gas pedal to the floor when cranking it. Doing so will help clear a flooded condition.

**Another thing that might help in your particular case would be to turn on the electric fuel pump for about ten seconds before trying to start the engine when hot, then turn it off and try starting with the gas pedal held to the floor. Release the pedal as soon as the engine starts.

Correcting any problems found will prevent wearing out the starter.

If you have been for a drive in warmer weather, it might be best not to stop the engine if you are only going to opean a garage door or other activity under 5 minutes or so.

A flooding carburetor can cause a lot of gas fumes in a closed garage. It might be best to park outside and let the car cool off for half an hour, then try the starting procedure above.

Older cars need a well ventilated garage area, since they do not have sealed fuel systems.

Especially in hot weather, they can emit a significant amount of fuel vapor, which is a dangerous nuisance in a closed space.

Thanks for the good advice. I understood the problem and can probably rule out the ignition as the cause.

You could still have a bad coil or ignition condenser, or a starter that drags when hot.

That said, flooding issues are very common after a hot shut down/restart in summer weather.

Modern gasoline is not designed to work well in carbureted systems. It's too volatile. It's not a problem in cool weather, but in hot weather and under some driving conditions, it can cause issues, especially if there is anything to aggravate the situation, like a leaky carburetor, air leaks in the fuel system, weak fuel pump, cooling system issues, sticking manifold heat valve, etc.

Even a slipping fan belt could cause problems, as could bugs in the radiator core, or anything else that reduced the efficiency of the cooling system.


A fuel line or added filter or fuel pump that is too near the exhaust or other source of heat can cause problems, usually in hotter weather.

I had good experience correcting vapor lock in my previously owned 47 Custom by adding a small amount of Diesel fuel when refueling. Five percent should be sufficient. This small amount did not affect engine performance and did not produce the tell-tale smoke and odor common to Diesel engines. This was in Austin, Texas which had high heat and humidity in the summer.