Questions and Answers

Honda Shuts Down In The Cold

Q. Hi, I have a 1989 Honda Accord, manual transmission, carburetor, 170,000 miles, A/C, P/S, cruise control (which doesn't work anymore). It runs great most of the time, but when the weather is cold (below 40) and especially cold and raining, it starts to lose gas pressure after driving 7 - 30 miles. Even if I floor the accelerator, I still get no response. So I have to pull over, turn the car off, and let it sit for 5 minutes. Then I start it backup and it runs fine.

I'm sure it has something to do with the weather because on Monday we drove 500 miles in it and the weather was dry and about 50 degrees, then the very next day it turned cold and rainy and after only seven miles the problem occurred.

I have had it checked on a computer, changed the distributor cap, spark plug wires, spark plugs and had a tune up, also changed both fuel filters. Do you have any ideas? Could it be the fuel pump? Oh yes and the battery/alternator light comes on sometimes, but then after I restart it, it turns off.

Please help!
Horacio

A. It sounds to me like the carburetor is icing up on you. This can happen on cold days and more so if it is damp out.

I'm sure you know what "wind chill" is. Well when the air goes through the carburetor throat it moves quite fast. And then when it passes through the venturi, it moves even faster. This will cause ice to form inside the venturi and eventually close it up enough where the air and fuel can't inside the engine. When you shut it off, the heat from the engine melts the ice and it will start up again and start the cycle over.

Car makers do have a system to prevent this. They wrap a metal cover around the exhaust manifold and run a flexible pipe to the air cleaner housing. Inside the air cleaner housing is an intake air temp sensor that controls a vacuum motor. This motor opens and closes a door in the housing allowing more or less warm air, heated by the manifold, to enter the engine.

It is easy enough to check. Make sure the shield around the manifold is in good shape and not rotted away. Then check the flexible hose and make sure it is securely attache to the shied and the air cleaner housing. Also make sure it is not torn or broken.

Make sure the door is not stuck closed. You can stick your finger in the air horn and move it by hand. Check to see if the vacuum lines are attached and in good shape.

If everything looks good, take the air hose off the air horn and start the car. Watch the door as it warms up and see if it moves. It should start off fully closed so air is drawn up from the exhaust manifold. As the sensor in the housing warms up, it should open allowing cold air to enter.

The system is pretty reliable and 95% of the problems are usually in the shield or the flexible hose.