Ok gang... here's one for ya'll...

Yesterday on my way to a show, I was out on a 2-lane highway, probably going about 45mph. I had to make a really fast stop... controlled, no skidding or tires squealing, but really harsh.

When I came to a stop, the engine stalled!

I immediately tried to crank it back up, but it just cranked and cranked... I gave it some gas, and still just cranked and cranked... then I noticed some smoke out the tail pipe... so it hit me than maybe the carb was flooded, so I waited a few seconds, (with really angry people behind me), and cranked again without touching the gas pedal and crossed my fingers. It eventually kicked over and started up. Thank god!

Anyway... my question is this...

Why did it stall?
Am I right, did the carb flood? If it flooded, is that normal for that situation, or is there something I can do/fix/replace to keep this from happening again?

Thanks!

The engine went to a high RPM condition with the throttle completely closed. This causes very high engine vacuum, much higher than idle vacuum. The very high vacuum is going to try to pull anything it can into the engine. With the throttle closed, all it can get is gas. So it pulls large quanties of gas, with little air, and floods the engine. This accounts for the black smoke and hard start. Once it does start and clears out, its fine again. I hate to say it, but this is entirely normal.

Computer controlled engines raise the idle to allow extra air and prevent this from happening. Fuel injections goes a step further and shuts off fuel until somewhere under 2000 RPM.

For older car, many have a dashpot. This can be vacuum, electrical, or mechanical (self) controlled. The vacuum or self control mechanical is the most common. When the throttle is opened it extends a link or rod to hold the idle speed high for a second or two to prevent your problem. They work well. Many of our cars don't have them. Dashpots are not as common on automatic trans cars. Many Olds 307 engines with automatics had them. The torque converter does not contine to drive the engine at high RPM as a manual does, so less flooding. Note I said less, not none. In severe decell, this will happen with an automatic.

If your car has a dashpot it needs adjusted or replaced. Most likely it won't have one. Raising the idle will help solve the problem, but can cause other symptoms if it's raised too much, like dieseling at shut down, or harsh shifting into gear.

If you step on the gas lightly on a rapid decell it would cure the symptom, but almost no one will do that. It's against our nature to apply gas when trying to stop. And many folks would push the gas too far and cause other problems, so I do not recommend trying this.

There is not much you can do about it. If it's a problem, you could install a dash pot if your car doesn't have one. You can also install a gulp valve like the (gasp) Chevettes used to have. These had a vacuum line to the intake manifold. When there was very high engine vacuum, it would open a passage from the air filter directly into the intake. These often tied in to the PCV line, between the valve and intake. When the engine slowed, and manifold vacuum dropped, the valve would close. Problem solved.

The situation for this to happen usually involves a panic stop. So it is generally not a problem. But it's good to know why when it does happen. Engines or cars prone to this problem on other than panic stops already have a dashpot.

The other option is to just ram the guy who pulled out in front of you, instead of slowing down fast. Naw, bad choice.

kstyer said: The other option is to just ram the guy who pulled out in front of you, instead of slowing down fast. Naw, bad choice.

What I find amazing is that when im driving my vette, and therefore usually mildly disobeying the speed limit, every moron on earth will pull out in front of me. when im driving my truck, which is uglier than sin and never gets above the speed limit, noone will pull out in front of me... I would love to run into some idiot with my truck...

Im the other kind of a$$hole, the kind who will not only flip someone off but follow them to their house to cuss them for being an idiot or pass them and slam on the brakes...

by the way... this is what a manual brake light override switches are great for.. turning them on to screw with someone when they do something stupid without having to worry about the timing when you step on the gas again... and to turn them off when you need to hide your braking from the cops......

Ben it is a weird thing of nature.

I used to work with a guy who said to when entering traffic, always pull out in front of some with a nicer car than yours. You'll never get hit. I think he was right.

I prefer the "dont pull out in front of someone if they will have to use their brakes to keep from hitting you" method.

This usually works well in places where people have a sense of common decency and will let you out if traffic doesnt permit a safe entrance. This will not work in places like LA where everyone thinks their time is more important than yours.

Ken,
Thanks for the thourogh (sp?) description!

One more question for ya...

If this happens again... what should I do to get it to start quickly and properly without more problems?

The same as anytime it's flooded. Put your foot to the floor, hold it there, and crank the engine. This allows the most air in to compensate for the extra fuel. It will be rough for a second or two, then it will be okay.

Ben,

I'll let you off with a warning this time...now be nice.

Please remove your override switch, if you ever do happen to get pulled over, and the nice Officer happens to be a gearhead, like me, YOU'RE SCREWED!!

Later, buddy.

Gribble123 said: Ben, I'll let you off with a warning this time...now be nice. Please remove your override switch, if you ever do happen to get pulled over, and the nice Officer happens to be a gearhead, like me, YOU'RE SCREWED!! Later, buddy.

I havent put a switch in my vettes... I used to do this when I was a little younger and wilder.. I also used a 100W PA system I used to use to say things like "Nice turn signal a$$hole"

I actually do consulting work for the local police, sheriff, and prosecutors... Around the time I started doing this I stopped being pulled over for being young and driving a vette on a day ending with "Y"....

havent had a ticket in three of four years now..

I wonder if under extreme braking it would help any to put the car into neutral, one with an automatic that is, or pushing in the clutch? That would let the engine wind down to idle on its own free from the drivetrain. (I have used that braking technique in the winter when the road conditions are questionable to get the most out of any traction I can get.)