Could a ping pong ball in the gas tank cause the car to stall?

I watched Law and Order CI episode Baggage from 2003.

The victim’s car mysteriously stalled and she could start it after a short wait. Her dad test drove the car a couple blocks with no problem.

The stalker followed the car until it stalls the next night, and she’s killed.

The shows explanation is a ping pong ball found in the tank. The suction from the fuel pump pulls the ball down and blocks the gas. The buoyant ping pong ball floats up after the car stalls.

The dad’s test drive was too short for the ball to suck down block the gas.

The theory is certainly imaginative and sounds plausible.

Is a ping pong ball in the tank a known prank? Similar to a potato in the tail pipe?

Some claims state that a ping pong ball can cause stalling in a car, especially when the fuel is low at around ¼ of the tank.

The claim said that the ping pong ball would be enough to clog the engine, leading it to stall. Once the engine stops running, it will release the ball due to the loss of power. Then, once it starts again, the ping pong ball would go again and clog it.

However, while the claim seems to be theoretically valid, it’s not a proven one. Further, no one has ever heard of it as accurate.

In other words, unless you’re driving a Ford, throwing a ping pong ball in the tank won’t cause it to stall.

A ping Pong ball is 40mm in diameter. Modern cars (from sometime in the 70s) have a smaller hole.

Yep. From the article I just linked: ‘In general, it’s pretty impossible to put a ping pong ball in the gas tank in modern car models.’

This seems improbable, considering the buoyancy of a ping-pong ball vs the closer proximity of the liquid gasoline to the outlet.

It would have been a great Mythbusters experiment. They could try it with a old car and modern.

No need for modern cars, as stated, the ping pong ball don’t fit.

As to old cars, maybe worth the experiment, but probably not good tv.

Modern cars have a vacuum on the fuel system to prevent gas vapor from polluting. Evap leaks are a common culprit for check engine light codes.

A ping pong ball might never rise to the surface. Assuming you could get it in the tank.

This was an old episode from 2003 and I thought the trick might work on a older car. It’s interesting that this is a known urban legend.

In the gas tank it might dissolve and gum up the fuel pump / lines.

The real way it could stall an engine is if it fit tightly in the exhaust pipe… mainly folks use a potato that is slightly larger than the exhaust pipe and jam it in real good. The car will start and may run a bit but as soon as pressure builds up, the engine will stall.

Every fuel pickup I’ve seen, whether it includes a in-tank pump or not, has a filter at the inlet. Think of an a small box or cylinder wrapped in fine plastic mesh. So even if the ping-pong ball were to float up against the filter - there would be plenty of area not blocked.

Come to think of it, by the time the ball is anywhere near the filter the vehicle’s gas level is too low anyway!

Now whether the ball would dissolve and plug up something further down the line, that’s another question. In my opinion, anything that small, it it would dissolve might, cause the engine to misfire a bit - but would not completely stall it.

I wish I had thought of this Ping-Pong ball trick back in the '70s. We just made do with the old potato-in-the-tailpipe.

I think the question has been answered, so I hope I’m not too soon to chime in with a similar question: what does putting sugar in the tank do to a motor vehicle?

When I was in my moped days (age 15-17), everybody was convinced that putting sugar in the tank would lead to a catastrophe, from clogging the carburetor to complete engine failure. I dated a girl who had dated an acquaintance of mine before who was angry at me. So one night when leaving a dance, another friend warned me that this guy had put sugar in the tank of my moped. The place was on a hill of my home town, so I could roll home without starting the motor. The next day I emptied the tank, cleaned it and filled in fresh fuel. Was that necessary? I still think so. Maybe the sugar wouldn’t have been that destructive, but at least it would have clogged the fuel filter, I think.

It would depend on how well the sugar dissolved and mixed with the gas.

Tank drained and cleaned, Fuel lines, and the filter would need replacing.

Fuel injectors on a modern car spray fuel at a high pressure. Any sticky, syrupy substance would clog them. They would probably need replacing.

I’m not sure about combustion. The valves might stick & burn if the engine ran very long.

It’s the labor that would be extremely expensive.

My dad told me it was a common sabotage tactic in WWII to add sugar to gasoline. The theory was it would create a gummy mess in the engine when the sugar heated up and became caramelized (think taffy) messing up the works, gumming up the pistons so they could not slide, etc.

I never asked him if he had any first hand knowledge of this. It seems to me that (a) sugar was hard to come by in WWII rationing and (b) probably needs a lot of sugar to effectively gum the motor. Does sugar dissolve in gasoline?

The othe trick was sand in the tank, that meant an engine rebuilt due to lost compression from excessive cylinder wear, plus whatever assorted other parts the sand would get into and create wear. But again, i would hope the oil filter would catch this, assuming 1940’s vehicles had filters. (My dad also mentioned his first car was a Morris Minor, but once he drove across Canada the engine needed rebuilding because in fine English quality control fashion, they never fully cleaned out all the sand from the engine casting and it got into the works. )

No car from at least the last 50+ years would be affected by a ball as described. The design of the pick-up tube inlet and it’s mesh “sock” filter, as described by Bonum_legatum, make that impossible. And assuming said ball doesn’t dissolve in the gasoline, it would float on top of it and never get near the tube anyway. I would say the story is a total fabrication that illustrates the typical Hollywood screenwriter’s knowledge and understanding of the workings of cars — essentially none to speak of.

Every source I found says that sugar does not dissolver in gasoline. It falls to the bottom of the tank and remains in granular form.

You don’t put the sand in the fuel tank, as with sugar it will sit on the bottom and at most clog up the fuel filter. You put the sand in the oil sump.

I’m not following how vacuum on the fuel system can affect the buoyancy of a ping-pong ball (not to mention the flow caused by the fuel pump overcoming the buoyancy of the ball). It seems to me like that sucker is going to float no matter what. I have no empirical data, however.

Not the first time Goren made a basic “urban legend” error. But I still like that episode.

The myth seemed plausible. I wasn’t sure how the inlet for the pump is shaped. I realize now how unlikey the ball could fit well enough to work.

Even more insidious is a red sponge rubber ball with a length of 1/4-in copper tubing rammed through it. The hole in the tubing will let the car start and idle, but much more than that will increase the back pressure so it stalls.