Vapor Lock

Vapor lock? What’s that? There you are, chugging up Trail Ridge Road, and your car starts to lose power. You pull off the road and the engine dies, and now the car won’t start! Arg! Don’t call a tow truck yet – it might not be serious.

Vapor lock occurs when the gasoline in your engine turns into vapor. This can happen due to high heat or high altitude, where gas turns to vapor at a lower temperature than normal. Often it’s a combination of both heat and altitude. Essentially, your engine is no longer getting gas. (Isn’t it funny that gas doesn’t work when it’s a gas?)

Symptoms include power loss, a feeling that the car is about to stall, a rough engine, or the car cranks but won’t start.

You can help prevent vapor lock by keeping your tank full, and by shifting into lower gear when driving up steep hills. Keeping the air conditioner off also helps.

If you start to notice power loss, don’t punch down on the gas or you’ll make it worse. Instead, shift into neutral and rev the engine.

If the car dies and you can’t get it started, try:

1) Loosening the gas cap, using a rag to help you. Be careful and stand back so as not to be sprayed by gasoline.

2) Starting the engine with the pedal all the way to the floor (don’t pump the pedal).

3) If that doesn’t work, open the hood and let the car cool for about half an hour and then try again.

If you can’t get it started after half an hour, there may be something else wrong. You may wish to call a tow truck at that point.

If you don’t have a cell phone or your cell phone doesn’t have service (which is common in Estes Park and Rocky Mountain National Park), then flag down a passing motorist and have them report your problem to the nearest ranger station. They will need to know your name, your location, what kind of car you are driving, what the license plate number is, and what the car’s symptoms are. If you have a motor service such as AAA, they will want to know that as well.

The more engine-savvy folks can try the following vapor lock remedies too:

Wrap a wet cloth around the fuel line. I’ve also heard of wrapping the fuel line with aluminum foil to attempt to prevent vapor lock in the first place.

Carefully hold open the choke flutter valve in the carburetor with a screwdriver. Just don’t ask us where the choke flutter valve is. (Hey, at least we know what a carburetor is!)

Fortunately, vapor lock is becoming less common thanks to today’s fuel injection systems, but it does still happen occasionally with older cars. Newer cars can sometimes get vapor lock too, especially when filled with gas that has a high ethanol content (the ethanol is more volatile). Just remember to take a cue from your car-stop for awhile, cool off, and enjoy the view.

Comments 2

  1. Debbie May 19, 2018
  2. John Crocombe January 9, 2020

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