On a hot day my car stalls when turning left, why?

Dear Car Talk

Dear Car Talk | Oct 01, 1989

Dear Tom and Ray:

We have a 1979 Toyota Corolla with 120,000 miles. The car has been good except for a problem that has cropped up every summer for the last five years. When the weather is hot--90 to 95 degrees-- and the car has been driven for an hour or two, it tends to stall on left hand turns. Once stalled, the car is difficult to restart, and we are often stranded in the path of oncoming traffic. This past summer, the car started to stall when the temperature was only in the 80s. The dealer has never been able to recreate the problem when we bring the car in for service. What do you recommend?

TOM: I'd recommend an insurance policy with me as the beneficiary if you plan to continue stalling in the path of oncoming traffic. After you've taken care of that, I'd recommend that your mechanic take a good look at your carburetor.

RAY: It's possible that your carburetor float is saturated and sinking under certain conditions. The carburetor float works just like a toilet bowl float. It tells the engine when the carburetor is full of gasoline--and when to shut off the flow. When it's saturated and sinking, the carburetor thinks it needs more gas when it really doesn't. More gas rushes in, your engine floods, and--kaput--you're staring an oncoming UPS truck right in the big brown grill.

TOM: The fact that it happens more readily in hot weather suggests that the more likely culprit is your fuel system ventilation equipment--especially the charcoal canister which we know you've never changed. If the compartment which houses the float can't ventilate, pressure builds up and causes your float-- especially if it's already on the edge of sinking--to go under. As your float gets more saturated over the years, the temperature and pressure required to make it sink decreases.

RAY: The reason it happens on left turns just has to do with the way the float is hinged. If the carburetor were facing the other way, it would happen on right hand turns. If you really don't want to buy a new carburetor, just have your mechanic move your old one a quarter turn so that it only stalls when you apply the brakes and make the car lean forward. Then the car will only stall when you were about to stop anyway.

TOM: When your mechanic finds out that he really can't do that, have him replace your float and check the fuel system ventilation--that should solve your problem. But make sure you find a repair shop you can drive to by making only right turns.

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