DEAR TALKING ABOUT CAR: I have a 1957 Chevrolet Nomad with a small block V8, high performance intake and carburetor etc. If I don’t start it for a few weeks, it looks like the gas tank is sucking up all the fuel. I tried installing a check valve, but it didn’t help.

I owned it for 48 years. Aside from installing an electric fuel pump, do you have any idea what may be causing it? Thanks and be careful. – John

DEAR READER: That’s the built-in anti-theft device, John. Actually, your theory makes sense, John. But also false. Like many of my theories.

Your problem is not that the gasoline is leaking from the carburetor and back down the fuel line to the gas tank. The problem is that the gasoline escapes from the bowl of the float and evaporates.

Here is how it all works. When you turn off the engine, your carburetor stores a bunch of fuel in the float chamber. This is the fuel that is used the next time you start the car.

In fact, if you severed the fuel line that comes from the tank, your car would still run for a good minute or more just on the fuel stored in the carburetor. But then you would have to write to me on how to replace a fuel line, so don’t do that.

Either way, it takes the fuel pump several seconds – while cranking and cranking the starter – to get enough fresh fuel into the carburetor to keep the engine running.

Normally that wouldn’t be a problem because like I said you have a lot of fuel in the carburetor until the fuel pump catches up.

But in your case, during those few weeks that the car is sitting, fuel escapes from your carburetor, maybe into the intake manifold, and evaporates. So when you start the car, the float chamber is dry.

Now you could, I guess, install an electric fuel pump with a switch on the dashboard. And you can turn on the switch a few seconds before you want to start the car. And that would fill the carburetor.

But you would be smarter to just replace the carburetor. There may be a crack or some other issue that is causing gasoline to leak. And if you eliminate that leak, who knows, you can go from 9.4 miles per gallon to 9.5.

DEAR TALKING ABOUT CAR: Several weeks ago I was waiting in a parking lot and was asked if I had any jumper cables. I did.

The guy who asked said that an approaching van offered him a jump but had no cables. While the pickup was positioned, I attached the cables to the dead car’s battery – correctly (red to positive, black to negative).

When Pickup Driver took the other end of the cables, I said “make sure you put the red clamp on the positive terminal”. He retorted, “I know what I’m doing!” Well, he didn’t. When he put them on, the red clamp on the dead car literally fried, melted some of them and came off – he had them inverted.

He got really pissed off when I told him he had them on the wrong terminals, instead of admitting his mistake. When he put them on the correct terminals (I checked), I was able to put the damaged clamp back on the positive terminal of the dead car’s battery, and the car started.

The owner of the dead car volunteered to buy me new jumper cables, which I refused. But it left me curious. As far as I know, the only damage was to my jumpers’ cable ties. It was minor enough that when I got home I fixed it with my Dremel, and it’s still very serviceable.

But did this error likely cause damage to the dead car or the pickup? If so, which one was most likely damaged? – Cary

DEAR READER: Either could have been damaged, but it seems neither was (sorry, I know you wanted the pickup to be fried).

I guess the spark that happened when the pickup guy plugged in the last bad cable blew the battery clamp off before the electronics could be damaged.

Of course, that’s a guess on my part. As far as I know, the driver of the pickup truck may be setting his heated seats to “charcoal” every time he turns on his wipers now. And the other guy’s AM radio can go through his radiator vents.

While it is certainly possible that electronic damage will appear later if an electronic module has been damaged, it often becomes apparent right away. So, I will keep hope that your jumper cables were the only victims here.

If the cable had been left there a little longer, many electronic components are susceptible to surges. Most modern cars now have 30, 40, or 50 computer modules that go into everything from engine management to power windows. This is where the damage would be noted.

But I think you’ve all had a chance, Cary. Send our best wishes to your jumper cables.

Ray Magliozzi provides car tips on Car Talk every Saturday. Email him by visiting

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