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I recently added an electric fuel pump just for cold starts. The Packard gurus said to add a check valve which I bought but never installed. This would avoid drawing the fuel through the electric pump when it was off. The pump is exactly what the gurus recommended, Airtex, 6 volts, etc..

When I run the car at freeway speeds (50-55) after about a half hour of travel, the car starts to hesitate and back fire. When I turn on the electric pump, it smooths out. I’m not sure if this happens in regard to speed or the time the engine is running.

When I came home Saturday, I had the electric pump running and it was leaking gas from the mechanical pump. I checked it running with the electric pump on and with the engine off and gas was coming from the mechanical pump.

Do I need to replace the mechanical pump?
Would adding the check valve help?
Is something wrong with the electric pump?
The electric pump did not seem to help much with cold starts.

Any ideas on what to do next?
Thanks in advance, you people are the best!

FYI : the car has been a little hard to start cold, but once it is running and before it starts to hestitate and backfire, it has never ran better! Smooth, quiet, good acceleration, just like a Packard should be.

Leaking fuel is a sign that your mechanical pump needs to be rebuilt or replaced

Check your crankcase oil for any sign of gasoline contamination.

If you are using an electric fuel pump to pump fuel through the stock fuel pump, there is a risk of the electric pump forcing gasoline into the crankcase if the stock pump diaphragm fails.

There is also an increased risk of fire due to presurized gasoline leaking near the exhaust header.

There should be no need of an electric pump if the stock pump is working as it should.

It would be possible to connect the electric pump to the fuel line between the stock pump and the carburetor, which would prevent the electric pump from being able to force fuel into the crank case. The electric pump shyould be connected in such a way that the stock pupm does not have to draw fuel through the electric pump, and vice-versa.

I've driven old cars all my life, with many of them having been sourced from junk yards and back lots and pastures. I have never found it necessary to add an electric fuel pump to any vehicle.